net.programmes/developer-tools

Format, minify, validate and convert JSON. Operations: "format" — Pretty-print JSON with a configurable indent.; "minify" — Strip all insignificant whitespace from JSON.; "validate" — Check whether th…

Pretty-print or minify already-serialized XML, and highlight it. Operations: "format" — Pretty-print XML with the chosen indent (server-safe string transform).; "minify" — Collapse whitespace between …

Format and minify SQL. Operations: "beautify" — Beautify SQL with newlines before clauses.; "minify" — Minify SQL to a single line.. Call with "operation" plus "input" (and "options" where relevant).

Format, minify and validate HTML. Operations: "format" — Pretty-print HTML.; "minify" — Minify HTML (strip comments and collapse whitespace).; "validate" — Check HTML for unclosed/mismatched tags.. Ca…

Encode and decode text in Base64, Base64URL, Base32, Base58, Base85 and hex. Operations: "encode" — Encode text into the chosen format.; "decode" — Decode text from the chosen format back to plain tex…

Parse, validate and normalize URLs. Operations: "parse" — Break a URL into its component parts.; "validate" — Validate a URL and run basic security/heuristic checks.; "normalize" — Normalize a URL (dr…

Decode JWT header and payload (no signature verification). Operations: "decode" — Decode a JWT into its header, payload and signature.. Call with "operation" plus "input" (and "options" where relevant…

Encode and decode HTML entities (named, decimal, hex). Operations: "encode" — Encode text into HTML entities.; "decode" — Decode HTML entities back to plain text.. Call with "operation" plus "input" (…

Percent-encode and decode URL strings. Operations: "encode" — Percent-encode a string.; "decode" — Decode a percent-encoded string.. Call with "operation" plus "input" (and "options" where relevant).

Compute MD5, SHA-1/256/384/512, CRC32 and HMAC digests. Operations: "hash" — Hash text with the chosen algorithm.; "hmac" — Compute an HMAC digest (SHA algorithms only).. Call with "operation" plus "i…

Generate and inspect UUIDs. Operations: "v4" — Generate one or more random (v4) UUIDs.; "v3" — Generate a name-based (v3 / MD5) UUID.; "parse" — Parse a UUID and report its version, variant and (where…

Generate strong random passwords and estimate their strength. Operations: "generate" — Generate a cryptographically random password.; "strength" — Estimate the entropy and strength bucket of a passwor…

Hash and verify passwords with bcrypt. Operations: "hash" — Hash a password with bcrypt at the given cost.; "verify" — Verify a plaintext password against a bcrypt hash.. Call with "operation" plus "i…

Generate cryptographically secure random strings. Operations: "generate" — Generate a secure random string from a chosen pattern.. Call with "operation" plus "input" (and "options" where relevant). No…

Convert and inspect Unix timestamps and dates. Operations: "to-date" — Convert a Unix timestamp (seconds) to a full date breakdown.; "parse-date" — Auto-detect and parse a date/timestamp string.. Call…

Convert colors between HEX, RGB, HSL, HSV and CMYK. Operations: "convert" — Convert a HEX color to every supported color space.; "palette" — Generate a color harmony palette from a base color.. Call w…

Convert numbers between binary, octal, decimal and hex. Operations: "convert" — Convert a number from one base to all supported bases.. Call with "operation" plus "input" (and "options" where relevant…

Convert text between camelCase, snake_case, kebab-case and more. Operations: "convert" — Convert text to a single chosen case.; "all" — Return every supported case transform at once.. Call with "opera…

Test a regex against a string and apply replacements. Operations: "test" — Find all matches of a regex pattern in a test string.; "replace" — Replace regex matches in a string.. Call with "operation" …

Compute a line-by-line diff between two texts. Operations: "compare" — Diff two texts and return the lines plus statistics.; "unified" — Produce a unified-diff text between two inputs.. Call with "ope…

Generate placeholder text in several styles. Operations: "generate" — Generate lorem ipsum (or themed) placeholder text.. Call with "operation" plus "input" (and "options" where relevant). Not repeata…

Count words/characters and compute readability statistics. Operations: "count" — Compute basic text statistics (words, characters, sentences, etc.).; "readability" — Compute readability scores (Flesch…

Describe cron expressions and compute upcoming run times. Operations: "describe" — Produce a human-readable description of a cron expression.; "next-runs" — Compute the next N run times for a cron exp…

Convert between JSON and CSV. Operations: "json-to-csv" — Convert a JSON array/object to CSV.; "csv-to-json" — Convert CSV to a JSON array.. Call with "operation" plus "input" (and "options" where rel…

Render Markdown to HTML, build a TOC and compute statistics. Operations: "render" — Render GitHub-flavored Markdown to sanitized HTML.; "toc" — Extract a table of contents from Markdown headers.; "sta…

Convert between YAML and JSON. Operations: "yaml-to-json" — Convert YAML to JSON.; "json-to-yaml" — Convert JSON to YAML.. Call with "operation" plus "input" (and "options" where relevant).

Generate TypeScript type declarations from a JSON sample. Operations: "generate" — Infer TypeScript interfaces/types from JSON.. Call with "operation" plus "input" (and "options" where relevant).

Check WCAG contrast between a foreground and background color. Operations: "check" — Compute the contrast ratio and WCAG pass/fail for a color pair.; "best-text" — Pick black or white text for the bes…

Build and parse base64 data URIs and embed snippets. Operations: "build-snippets" — Build HTML/CSS/Markdown snippets from an existing data URI.. Call with "operation" plus "input" (and "options" where…

Generate a combined .gitignore from template keys. Operations: "generate" — Combine one or more template keys into a .gitignore.; "templates" — List the available .gitignore template keys.. Call with …

Look up and search HTTP status codes. Operations: "lookup" — Look up a single status code by number.; "search" — Search status codes by number, name or description.. Call with "operation" plus "input"…

Turn arbitrary text into a clean, URL-safe slug. Operations: "slugify" — Generate a URL slug from text.. Call with "operation" plus "input" (and "options" where relevant).

Convert between octal and symbolic Unix file permissions. Operations: "octal-to-symbolic" — Convert octal permissions (e.g. "755") to a symbolic string and description.; "symbolic-to-octal" — Convert …

Build the standard WIFI: payload string for a WiFi QR code. Operations: "payload" — Build the WIFI: payload string a phone scans to auto-join a network.. Call with "operation" plus "input" (and "optio…

Minify or beautify CSS. Operations: "minify" — Minify CSS (strip comments and whitespace).; "beautify" — Beautify CSS (one declaration per line, indented).. Call with "operation" plus "input" (and "op…

Convert a curl command into fetch / Python / Node snippets. Operations: "convert" — Parse a curl command and generate code snippets.. Call with "operation" plus "input" (and "options" where relevant).

Infer a draft-07 JSON Schema from sample JSON. Operations: "generate" — Infer a draft-07 JSON Schema from sample JSON. Call with "operation" plus "input" (and "options" where relevant).

Parse a CIDR block into its network, broadcast and host range. Operations: "calculate" — Calculate the network, broadcast, mask and host range for a CIDR block.. Call with "operation" plus "input" (an…

Parse a User-Agent string into browser, engine, OS and device. Operations: "parse" — Parse a User-Agent string into browser, engine, OS and device details.. Call with "operation" plus "input" (and "op…

Generate harmony, shade and tint palettes from a base HEX color. Operations: "generate" — Generate harmony, shade and tint palettes from a base HEX color.. Call with "operation" plus "input" (and "opt…

Analyze a password and estimate its entropy, strength and crack time. Operations: "analyze" — Analyze a password and estimate its entropy, strength and crack time.. Call with "operation" plus "input" …

Query a JSON document with a JSONPath expression. Operations: "query" — Evaluate a JSONPath expression against a JSON document.. Call with "operation" plus "input" (and "options" where relevant).

Generate a time-based one-time password (TOTP) from a base32 secret. Operations: "generate" — Generate the current TOTP code for a base32 secret.. Call with "operation" plus "input" (and "options" whe…

Parse a data size and convert it to bytes plus decimal and binary units. Operations: "convert" — Parse a data size and convert it to bytes, decimal and binary units.. Call with "operation" plus "input…

Look up MIME types by file extension or MIME type. Operations: "lookup" — Search MIME types by extension or MIME type.. Call with "operation" plus "input" (and "options" where relevant).

Sort, reverse, deduplicate and clean up lines of text. Operations: "process" — Sort, deduplicate and clean lines of text.. Call with "operation" plus "input" (and "options" where relevant).

Sign a JSON payload into a JWT with an HMAC secret. Operations: "sign" — Sign a JSON payload into a JWT using an HMAC secret.. Call with "operation" plus "input" (and "options" where relevant).

Generate a lexicographically sortable ULID. Operations: "generate" — Generate a new ULID.. Call with "operation" plus "input" (and "options" where relevant). Not repeatable: generate returns a differe…

Escape and unescape strings for JSON, JS, HTML, URL and regex. Operations: "escape" — Escape a string for the chosen context.; "unescape" — Unescape a string from the chosen context.. Call with "opera…

Convert text to and from character codes in several bases. Operations: "to-codes" — Convert text to character codes.; "from-codes" — Convert character codes back to text.. Call with "operation" plus "…

Convert between integers and Roman numerals. Operations: "to-roman" — Convert an integer to a Roman numeral.; "from-roman" — Convert a Roman numeral to an integer.. Call with "operation" plus "input" …

Compare two JSON documents and report added, removed and changed values. Operations: "diff" — Diff two JSON documents by path.. Call with "operation" plus "input" (and "options" where relevant).

Translate text to and from Morse code. Operations: "encode" — Convert text to Morse code.; "decode" — Convert Morse code to text.. Call with "operation" plus "input" (and "options" where relevant).

Convert CSV or TSV rows into a Markdown table. Operations: "generate" — Build a Markdown table from delimited rows.. Call with "operation" plus "input" (and "options" where relevant).

Sign a message with HMAC using a secret key and SHA-2 algorithm. Operations: "sign" — Compute an HMAC signature for a message.. Call with "operation" plus "input" (and "options" where relevant).

Convert a numeric value between CSS units (px, rem, em, pt, pc, %). Operations: "convert" — Convert a numeric value from one CSS unit to another.. Call with "operation" plus "input" (and "options" whe…

Convert between JSON and XML. Operations: "to-xml" — Convert JSON to XML.; "to-json" — Convert XML to JSON.. Call with "operation" plus "input" (and "options" where relevant).

Break a string into per-character Unicode details. Operations: "inspect" — Inspect each character of a string (code point, category, bytes).. Call with "operation" plus "input" (and "options" where re…

Parse, compare, sort and bump Semantic Versions, and test versions against npm-style ranges. Operations: "parse" — Parse a SemVer 2.0.0 version into its components.; "compare" — Compare two versions b…

Convert between ISO 8601 durations, seconds, clock time and human text like "1h30m" or "90 minutes". Operations: "convert" — Parse any duration (ISO 8601, 1h30m, 90 minutes, 1:30:00, seconds) into eve…

Generate NanoIDs or custom-alphabet random IDs with crypto randomness, plus a collision-probability estimate. Operations: "generate" — Generate one or more random IDs (default: 21-char URL-safe NanoID…

Encode and decode UTF-8 text as Base32 (RFC 4648 + hex), Crockford Base32, Base58 (Bitcoin), Ascii85 or Z85. Operations: "encode" — Encode UTF-8 text in the chosen scheme.; "decode" — Decode to UTF-8 …

Validate check digits: Luhn card numbers (with brand), IBAN mod-97, ISBN-10/13 and EAN/UPC barcodes. Format only — nothing is looked up or stored. Operations: "validate" — Validate a number, auto-dete…

Decode PEM/DER X.509 certificates: subject, issuer, validity, SANs, key type/size, signature algorithm, extensions and fingerprints. Operations: "decode" — Decode every certificate in a PEM bundle (or…

Convert dotenv files to JSON and back, with dotenv-compatible quoting, escapes, comments, export prefixes and multi-line values, plus validation warnings. Operations: "to-json" — Parse a .env file int…

Convert TOML 1.0 to JSON and JSON to TOML, reporting anything that cannot round-trip. Operations: "to-json" — Parse TOML and return pretty-printed JSON.; "to-toml" — Convert a JSON object to TOML (nul…

Parse a Content-Security-Policy, explain each directive and flag weaknesses (unsafe-inline, wildcards, missing object-src/base-uri/frame-ancestors…). Operations: "evaluate" — Parse a CSP header and re…

Grade pasted HTTP response headers (HSTS, CSP, nosniff, framing, Referrer-Policy, Permissions-Policy, COOP/COEP/CORP, cookies) A+ to F. Parses text only; never fetches a URL. Operations: "grade" — Gra…

Expand and compress IPv6 addresses (RFC 5952), classify them (link-local, ULA, multicast, documentation…), extract embedded IPv4, do prefix and range maths, and build ip6.arpa names. Operations: "anal…

Build campaign URLs with utm_* parameters, parse and lint tagged links, and strip UTM and click-ID tracking parameters. Operations: "build" — Add UTM parameters to a URL, normalising case and spaces, …

Reduce a ratio or resolution to lowest terms, name the nearest common ratio, solve the missing dimension and write CSS aspect-ratio. Operations: "analyze" — Reduce a ratio or size (16:9, 1920x1080, 2.…

Convert HTML or SVG markup to React JSX: className/htmlFor, camelCased SVG attributes, style objects, self-closing tags, JSX comments. Operations: "convert" — Convert an HTML fragment or document to J…

Convert JSON5, JSONC (tsconfig, VS Code settings) and relaxed JSON to strict JSON, or reformat them with comments kept, reporting every non-JSON feature used. Operations: "to-json" — Convert JSON5 / J…

Find and remove invisible Unicode (zero-width, bidi/Trojan Source, tag-character smuggling), fix line endings, trailing whitespace, tabs and smart quotes, and normalise Unicode. Operations: "scan" — R…

Days, months and business days between dates, add or subtract durations, ISO week numbers and day of year, and DST-aware elapsed time between local times. Operations: "diff" — Difference between two d…

Minify an SVG and encode it as a compact percent-encoded (or base64) data URI, with background-image and mask-image CSS. Operations: "encode" — Optimise an SVG and return url-encoded and base64 data U…

Decode IDs: Snowflake, MongoDB ObjectId, KSUID, TypeID, ULID, UUID and CUID2 — timestamp, machine fields and randomness. Operations: "decode" — Detect each ID's format and take it apart (one ID per li…

Convert docker run commands to a Docker Compose file and Compose services back. Operations: "to-compose" — Convert one or more docker run commands to Compose services (ports, volumes, env, name, resta…

Test .gitignore or glob patterns against a list of paths and see which rule matched each one. Operations: "test" — Match paths against gitignore rules (negation, anchoring, **, directory-only) or plai…

Convert internationalised domain names to and from Punycode (RFC 3492): bücher.example ⇄ xn--bcher-kva.example. Operations: "to-ascii" — Encode each Unicode label as an xn-- label (one domain, email o…

Inspect IEEE 754 float32/float64: sign, exponent and mantissa bits, hex, the exact stored value and the rounding error. Operations: "inspect" — Read a decimal (0.1, -2.5e-8, Infinity, NaN) or a bit pa…

Convert HTML to Markdown (CommonMark + GitHub tables), dropping scripts and styles. Operations: "convert" — Convert an HTML page or fragment to Markdown: headings, lists, links, images, code blocks, t…

Build robots.txt that treats search engines, AI answer bots and AI training crawlers separately; validate llms.txt. Operations: "build" — Build robots.txt: allow or block search engines, AI answer eng…

gzip, deflate (zlib) or raw-deflate text to Base64 or hex, and decompress it back. Operations: "compress" — Compress UTF-8 text with gzip, deflate (zlib) or raw deflate.; "decompress" — Decompress Bas…

Decode a SAMLRequest or SAMLResponse (Base64, or deflate + Base64) and summarise it. Signatures are not verified. Operations: "decode" — Decode a SAML message and return its issuer, status, NameID, au…

Inspect a CSR (subject, SANs, key, signature check), OpenSSH public keys (type, bits, ssh-keygen fingerprints) or a JWK / JWKS (RFC 7638 thumbprint, PEM and OpenSSH forms). Private keys are refused. O…

Validate JSON data against a JSON Schema (drafts 2020-12, 2019-09, 7 and 4) and list each error with its data path and schema keyword. Operations: "validate" — Validate JSON data against a JSON Schema…

HTTP 100 Continue is an interim response telling the client that the request headers were accepted and it should go ahead and send the request body.

HTTP 101 Switching Protocols means the server agrees to switch the connection to the protocol the client asked for in its Upgrade header, most commonly WebSocket.

HTTP 102 Processing is an interim WebDAV response saying the server has received the request and is still working on it, so the client should not time out.

HTTP 103 Early Hints is an interim response that sends Link headers early so the browser can preload or preconnect to resources while the server is still preparing the final response.

HTTP 200 OK means the request succeeded and the response body contains the result — the resource for a GET, or the outcome of the action for a POST.

HTTP 201 Created means the request succeeded and a new resource was created, usually identified by the Location header in the response.

HTTP 202 Accepted means the request was accepted for processing but the work has not been completed yet, and it may still fail.

HTTP 203 Non-Authoritative Information means the request succeeded but a transforming proxy modified the payload the origin server sent.

HTTP 204 No Content means the request succeeded and there is intentionally no response body to send back.

HTTP 205 Reset Content means the request succeeded and the client should reset the document view — for example clear the form that was just submitted.

HTTP 206 Partial Content means the server is returning only the byte range(s) the client asked for with a Range header.

HTTP 207 Multi-Status is a WebDAV response whose XML body carries separate status codes for multiple sub-operations or resources.

HTTP 208 Already Reported is used inside a WebDAV 207 multistatus body to say a resource was already listed earlier and is not repeated.

HTTP 226 IM Used means the server fulfilled a GET and the response is the result of one or more instance manipulations (delta encoding) applied to the current resource.

HTTP 300 Multiple Choices means the resource has several representations and the client (or user) should choose one.

HTTP 301 Moved Permanently means the resource has permanently moved to the URL in the Location header and future requests should use that new URL.

HTTP 302 Found means the resource is temporarily at the URL in the Location header, and the client should keep using the original URL for future requests.

HTTP 303 See Other means the client should retrieve the result with a GET request to the URL in the Location header.

HTTP 304 Not Modified means the cached copy the client already has is still valid, so the server sends no body and the client should use its cache.

HTTP 305 Use Proxy is a deprecated code that told the client to repeat the request through the proxy named in the Location header.

HTTP 306 (Unused) is reserved and unused; it was defined in an earlier draft and must not be sent.

HTTP 307 Temporary Redirect means the resource is temporarily at the Location URL and the client must repeat the request there with the same method and body.

HTTP 308 Permanent Redirect means the resource has permanently moved to the Location URL and the client must repeat the request there with the same method and body.

HTTP 400 Bad Request means the server cannot or will not process the request because of something it sees as a client error, such as malformed syntax or an invalid body.

HTTP 401 Unauthorized means the request lacks valid authentication credentials for the resource — the client is not logged in, or its token is missing, expired or invalid.

HTTP 402 Payment Required is reserved for future use; some APIs use it non-standardly to signal that payment, a subscription or credits are needed.

HTTP 403 Forbidden means the server understood the request but refuses to authorize it — the client is not allowed to access the resource, and re-authenticating will not help.

HTTP 404 Not Found means the server cannot find anything at the requested URL — the page or resource does not exist, or the server is choosing not to reveal it.

HTTP 405 Method Not Allowed means the URL exists but does not support the HTTP method used, such as a POST to an endpoint that only accepts GET.

HTTP 406 Not Acceptable means the server cannot produce a response matching the Accept headers the client sent (content type, language or encoding).

HTTP 407 Proxy Authentication Required means the client must authenticate with the proxy between it and the server before the request can be forwarded.

HTTP 408 Request Timeout means the server gave up waiting for the client to finish sending the request and closed the connection.

HTTP 409 Conflict means the request conflicts with the current state of the resource, such as a duplicate record or an edit based on an outdated version.

HTTP 410 Gone means the resource was intentionally and permanently removed and no forwarding address is known.

HTTP 411 Length Required means the server refuses a request that has a body but no Content-Length header.

HTTP 412 Precondition Failed means a condition in the request headers, such as If-Match or If-Unmodified-Since, evaluated to false, so the server did not apply the request.

HTTP 413 Content Too Large means the request body is larger than the server is willing or able to process — formerly called "Payload Too Large" and "Request Entity Too Large".

HTTP 414 URI Too Long means the request URL is longer than the server is willing to interpret.

HTTP 415 Unsupported Media Type means the server refuses the request because the body format given in Content-Type (or Content-Encoding) is not supported for that endpoint.

HTTP 416 Range Not Satisfiable means none of the byte ranges in the request’s Range header can be served, usually because they lie beyond the end of the file.

HTTP 417 Expectation Failed means the server cannot meet the requirement in the request’s Expect header.

HTTP 418 I'm a teapot is a joke status code from the 1998 April Fools’ RFC 2324 ("Hyper Text Coffee Pot Control Protocol"), meaning the server refuses to brew coffee because it is a teapot.

HTTP 419 Page Expired is a non-standard Laravel status meaning the CSRF token was missing or expired, so the form submission was rejected.

HTTP 420 Enhance Your Calm is a non-standard status the old Twitter API returned when a client was being rate limited.

HTTP 421 Misdirected Request means the request was sent to a server that is not configured to produce responses for that combination of scheme and host.

HTTP 422 Unprocessable Content means the server understands the content type and the syntax is correct, but the content itself failed validation — formerly called "Unprocessable Entity".

HTTP 423 Locked is a WebDAV code meaning the target resource is locked and cannot be modified.

HTTP 424 Failed Dependency is a WebDAV code meaning the request failed because an operation it depended on failed.

HTTP 425 Too Early means the server will not process a request sent in TLS 1.3 early data (0-RTT) because it might be replayed.

HTTP 426 Upgrade Required means the server refuses to handle the request with the current protocol and names the required one in an Upgrade header.

HTTP 428 Precondition Required means the server requires the request to be conditional — it must include a header such as If-Match — to prevent lost updates.

HTTP 429 Too Many Requests means the client has sent too many requests in a given amount of time and is being rate limited.

HTTP 431 Request Header Fields Too Large means the server refuses the request because a header, or the headers in total, are too large.

HTTP 440 Login Time-out is a non-standard Microsoft IIS status meaning the client’s session has expired.

HTTP 444 No Response is a non-standard nginx code that makes the server close the connection without sending any response at all.

HTTP 449 Retry With is a non-standard Microsoft status meaning the request should be retried after performing the appropriate action.

HTTP 451 Unavailable For Legal Reasons means the server is denying access to the resource because of a legal demand, such as a court order or government censorship.

HTTP 460 Client Closed Connection is a non-standard AWS Application Load Balancer code logged when the client closed its connection to the load balancer before the response was ready.

HTTP 463 Too Many Forwarded IP Addresses is a non-standard AWS Application Load Balancer code meaning the request’s X-Forwarded-For header listed more than 30 IP addresses.

HTTP 464 Incompatible Protocol Versions is a non-standard AWS Application Load Balancer code meaning the request’s protocol does not match the protocol version configured on the target group.

HTTP 494 Request Header Too Large is a non-standard nginx code meaning the request headers exceeded large_client_header_buffers; clients normally see it as 400.

HTTP 495 SSL Certificate Error is a non-standard nginx code meaning the client presented an invalid TLS client certificate; nginx logs 495 but sends the client a 400 ("The SSL certificate error").

HTTP 496 SSL Certificate Required is a non-standard nginx code meaning a required TLS client certificate was not provided; nginx logs 496 but sends the client a 400 ("No required SSL certificate was s…

HTTP 497 HTTP Request Sent to HTTPS Port is a non-standard nginx code meaning a plain-HTTP request arrived on a port configured for HTTPS; nginx logs 497 but sends the client a 400 ("The plain HTTP re…

HTTP 499 Client Closed Request is a non-standard nginx code logged when the client closed the connection before nginx could send the response.

HTTP 500 Internal Server Error means the server hit an unexpected condition — usually an unhandled exception or misconfiguration — that prevented it from fulfilling the request.

HTTP 501 Not Implemented means the server does not support the functionality required to fulfil the request, typically an HTTP method it does not recognize at all.

HTTP 502 Bad Gateway means a server acting as a gateway or proxy received an invalid response — or no response — from the upstream server it forwarded the request to.

HTTP 503 Service Unavailable means the server is temporarily unable to handle the request, usually because it is overloaded or down for maintenance.

HTTP 504 Gateway Timeout means a gateway or proxy did not receive a response from the upstream server in time.

HTTP 505 HTTP Version Not Supported means the server does not support the major HTTP version used in the request.

HTTP 506 Variant Also Negotiates means the server has a content-negotiation misconfiguration: the chosen variant is itself configured to negotiate, creating a loop.

HTTP 507 Insufficient Storage is a WebDAV code meaning the server cannot store the representation needed to complete the request.

HTTP 508 Loop Detected is a WebDAV code meaning the server hit an infinite loop while processing the request.

HTTP 509 Bandwidth Limit Exceeded is a non-standard status used by some shared-hosting setups (Apache modules, cPanel) when a site exceeds its bandwidth allowance.

HTTP 510 Not Extended means further extensions to the request are required for the server to fulfil it (from the historic HTTP Extension Framework).

HTTP 511 Network Authentication Required means the client must authenticate to gain network access — typically a captive portal on public Wi-Fi.

HTTP 520 Web Server Returned an Unknown Error is a non-standard Cloudflare status meaning the origin server returned an empty, unknown or unexpected response.

HTTP 521 Web Server Is Down is a non-standard Cloudflare status meaning the origin server refused the connection from Cloudflare.

HTTP 522 Connection Timed Out is a non-standard Cloudflare status meaning Cloudflare could not complete a TCP connection to the origin in time.

HTTP 523 Origin Is Unreachable is a non-standard Cloudflare status meaning Cloudflare cannot reach the origin server at all, often due to DNS or routing problems.

HTTP 524 A Timeout Occurred is a non-standard Cloudflare status meaning Cloudflare connected to the origin but the origin did not send an HTTP response before the Proxy Read Timeout (120 seconds by de…

HTTP 525 SSL Handshake Failed is a non-standard Cloudflare status meaning the TLS handshake between Cloudflare and the origin failed.

HTTP 526 Invalid SSL Certificate is a non-standard Cloudflare status meaning Cloudflare could not validate the origin’s TLS certificate in Full (strict) mode.

HTTP 530 Origin Error is a non-standard Cloudflare status returned together with a Cloudflare 1xxx error, such as error 1016 (Origin DNS error).

HTTP 561 Unauthorized is a non-standard AWS Application Load Balancer code meaning a listener rule that authenticates users (OIDC or Amazon Cognito) got an error back from the identity provider.

The Content-Type header states the media type (MIME type) of the message body, plus parameters such as charset.

The Content-Length header gives the size of the message body in bytes.

The Content-Encoding header lists the compression applied to the body, such as gzip, br (Brotli) or zstd.

The Content-Disposition header tells the browser whether to show a response inline or download it as an attachment, and suggests a file name.

The Content-Language header describes the natural language(s) of the intended audience of the body.

The Content-Location header gives a URL that identifies the specific representation in the body — for example the language- or format-specific variant chosen by content negotiation.

The Use-As-Dictionary header tells the browser to keep this response as a compression dictionary for future requests whose URLs match a pattern.

The Available-Dictionary header carries the SHA-256 hash of the best compression dictionary the browser holds for this URL, so the server can delta-compress the response against it.

The Content-Digest header carries a hash of the actual message body so the receiver can check its integrity.

The Repr-Digest header carries a hash of the whole selected representation, independent of range requests or how this particular message was framed.

The Want-Content-Digest header asks the other side to send a Content-Digest, listing acceptable hash algorithms with preference weights from 0 to 10.

The Signature-Input header lists, for each HTTP Message Signature in the message, which components were signed and the signature parameters (created, keyid, alg …).

The Signature header carries one or more HTTP Message Signatures (RFC 9421), each a base64 byte sequence under the label used in Signature-Input.

The Transfer-Encoding header lists hop-by-hop transfer codings applied to the body in HTTP/1.1 — in practice "chunked", used when the length is not known in advance.

The Trailer header announces which header fields will be sent in the trailer section after a streamed body.

The TE header tells the server which transfer codings the client accepts, and with "trailers" that it can handle trailer fields.

The Accept header lists the media types the client can handle, with optional q-value preferences.

The Accept-Encoding header lists the compression algorithms the client understands, such as gzip, br and zstd.

The Accept-Language header lists the user's preferred natural languages, most preferred first or by q-value.

The Accept-Charset header listed the character encodings a client accepts; modern browsers no longer send it.

The Vary header lists the request headers that influenced the response, so caches store a separate copy per combination.

The User-Agent header identifies the client software — browser, library or bot — making the request.

The From header gives an email address for the human or organisation responsible for the client — in practice, a contact address for a crawler.

The Accept-CH header asks the browser to send specific Client Hints — device, network, preference and User-Agent details — on subsequent requests.

The Critical-CH header names Client Hints the response depends on: if the browser could have sent one but did not, it retries the request once with the hint included.

The Sec-CH-UA header is the User-Agent Client Hint carrying the browser's brands and their major versions, the structured replacement for parsing User-Agent.

The Sec-CH-UA-Mobile header tells the server whether the browser wants a "mobile" experience, as the Structured Field boolean ?1 (yes) or ?0 (no).

The Sec-CH-UA-Platform header names the operating system the browser runs on, such as "Windows", "macOS" or "Android".

The Sec-CH-UA-Platform-Version header gives the operating system version, which the frozen User-Agent string no longer reveals; sent only after Accept-CH.

The Sec-CH-UA-Full-Version-List header lists each browser brand with its full version number, the opt-in counterpart of Sec-CH-UA.

The Sec-CH-UA-Model header gives the device model name on Android (an empty string on desktop); sent only after Accept-CH.

The Sec-CH-Prefers-Color-Scheme header tells the server whether the user prefers a "light" or "dark" colour scheme, mirroring the prefers-color-scheme media query.

The Sec-CH-Device-Memory header gives the device's approximate RAM in GiB, rounded to a power of two, so servers can send lighter pages to low-memory devices.

The Sec-CH-DPR header gives the device pixel ratio (window.devicePixelRatio), so an image server can pick the right resolution.

The Sec-CH-Viewport-Width header gives the browser's layout viewport width in CSS pixels (window.innerWidth).

The Save-Data header signals, with the value on, that the user has asked the browser to reduce data usage.

The ECT header gives the effective connection type the browser measured — slow-2g, 2g, 3g or 4g — regardless of the actual radio technology.

The Cache-Control header carries caching directives — how long a response may be reused, by whom, and whether it must be revalidated.

The Expires header gives the date after which a response is considered stale.

The Age header tells how many seconds a response has been sitting in a cache since it was fetched or revalidated at the origin.

The Pragma header is the HTTP/1.0 predecessor of Cache-Control; "Pragma: no-cache" is its only common use.

The ETag header is an opaque identifier for a specific version of a resource, used for cache revalidation and optimistic concurrency.

The Last-Modified header gives the date and time the origin believes the resource was last changed.

The Cache-Status header reports how each cache along the path handled the request — hit, miss, forwarded and why.

The CDN-Cache-Control header gives caching directives that only CDNs obey, separate from the Cache-Control seen by browsers.

The No-Vary-Search header tells caches which URL query parameters do not change the response, so /page?utm_source=x can reuse the cached /page.

The Warning header carried extra status information, mostly from caches (110 Response is Stale, 214 Transformation Applied); RFC 9111 made it obsolete.

The If-None-Match header makes a request conditional on the resource's ETag not matching — the server replies 304 Not Modified if the client's copy is current.

The If-Match header makes a state-changing request apply only if the resource still has the given ETag, preventing lost updates.

The If-Modified-Since header asks the server to send the resource only if it changed after the given date, otherwise 304 Not Modified.

The If-Unmodified-Since header makes a request apply only if the resource has not changed since the given date (412 otherwise).

The If-Range header makes a Range request conditional: send the requested part if the resource is unchanged, otherwise send the whole new resource.

The Range header asks the server for only part of a resource, in byte ranges.

The Accept-Ranges header advertises whether the server supports range requests for this resource.

The Content-Range header says which part of the full resource a partial (206) response contains, and the total size.

The Authorization header carries the client's credentials for the server, in a scheme such as Bearer or Basic.

The WWW-Authenticate header is sent with a 401 response to tell the client which authentication scheme(s) to use and with what parameters.

The Proxy-Authorization header carries credentials for a proxy that demanded authentication with 407.

The Proxy-Authenticate header is sent by a proxy with 407 Proxy Authentication Required to say how to authenticate to it.

The X-API-Key header is a common convention for sending a static API key with each request.

The Set-Cookie header tells the browser to store a cookie, with attributes controlling its lifetime, scope and security.

The Cookie header sends the cookies the browser has stored for this host and path back to the server.

The Origin header tells the server the scheme, host and port of the page that initiated the request, without the path.

The Access-Control-Allow-Origin header tells the browser which origin may read the response from cross-origin JavaScript (fetch/XHR).

The Access-Control-Allow-Credentials header allows a cross-origin response to be read when the request included credentials (cookies, Authorization or client certificates).

The Access-Control-Allow-Methods header lists the HTTP methods allowed for a cross-origin request, in the response to a preflight.

The Access-Control-Allow-Headers header lists the request headers a cross-origin request may use, in the response to a preflight.

The Access-Control-Expose-Headers header lists response headers that cross-origin JavaScript is allowed to read.

The Access-Control-Max-Age header says how many seconds the browser may cache a preflight response.

The Access-Control-Request-Method header is sent by the browser in a CORS preflight (OPTIONS) to say which method the real request will use.

The Access-Control-Request-Headers header is sent in a CORS preflight to list the non-safelisted headers the real request will carry.

The Strict-Transport-Security header tells browsers to use only HTTPS for this host for the given time, turning any http:// link or typed URL into https:// before a request is sent (HSTS).

The Content-Security-Policy header restricts which sources a page may load scripts, styles, images, frames and connections from, mitigating cross-site scripting and clickjacking.

The Content-Security-Policy-Report-Only header applies a CSP in monitoring mode: violations are reported but nothing is blocked.

The X-Content-Type-Options header stops browsers from guessing ("sniffing") a response's type instead of trusting Content-Type; its only value is nosniff.

The X-Frame-Options header controls whether the page may be shown in a frame on other sites, defending against clickjacking.

The X-XSS-Protection header controlled the XSS auditor of old browsers; modern browsers have removed that filter, and the header should be set to 0 or omitted.

The Referrer-Policy header controls how much of the current URL browsers send in the Referer header when following links or loading resources.

The Permissions-Policy header turns browser features such as camera, microphone, geolocation and fullscreen on or off for a page and the frames it embeds.

The Cross-Origin-Opener-Policy header isolates a page's browsing context group from cross-origin windows it opens or is opened by, so they cannot hold a reference to it.

The Cross-Origin-Embedder-Policy header requires every cross-origin resource a page loads to explicitly allow it (via CORS or CORP), a prerequisite for cross-origin isolation.

The Cross-Origin-Resource-Policy header declares which origins may embed this resource with no-cors requests, such as from img and script elements.

The Clear-Site-Data header tells the browser to delete cookies, storage and/or cache for the site — typically on logout.

The Upgrade-Insecure-Requests header is sent by browsers on navigations (value 1) to signal they prefer an encrypted, authenticated response.

The X-Permitted-Cross-Domain-Policies header tells Adobe clients (Flash, Acrobat) whether they may load cross-domain policy files from the site; "none" forbids it.

The Integrity-Policy header makes the browser refuse scripts (and, where supported, stylesheets) that are loaded without Subresource Integrity metadata.

The Origin-Agent-Cluster header asks the browser to isolate the document by origin rather than by site (value ?1), so same-site but cross-origin pages cannot share an agent cluster.

The Document-Policy header configures document-wide behaviours and opt-ins — such as allowing JavaScript self-profiling — as a Structured Field dictionary.

The Expect-CT header asked browsers to require Certificate Transparency for the site; it is obsolete because browsers now require CT for all publicly trusted certificates.

The Public-Key-Pins header pinned the public keys a site would accept in its certificate chain (HPKP); browsers removed it because a mistake could lock users out for months.

The Sec-Fetch-Site header tells the server how the request's initiator relates to the target: same-origin, same-site, cross-site, or none (typed URL, bookmark).

The Sec-Fetch-Mode header tells the server the request mode: navigate, cors, no-cors, same-origin or websocket.

The Sec-Fetch-Dest header tells the server where the response will be used — document, iframe, image, script, style, empty (fetch/XHR) and so on.

The Sec-Fetch-User header is sent with value ?1 when a navigation was triggered by user activation, such as a click.

The Sec-Purpose header marks a request made ahead of need — a prefetch or a prerender — rather than for something the user is looking at right now.

The Speculation-Rules header points the browser at external speculation-rules JSON files describing which pages to prefetch or prerender.

The Supports-Loading-Mode header lets a page opt in to being loaded in special modes — prerendered by a cross-origin, same-site referrer, or with its cross-origin iframes prerendered too.

The Host header gives the host name (and port) the client wants, so one IP address can serve many sites (virtual hosting).

The Connection header controls whether the HTTP/1.1 connection stays open after this message and lists hop-by-hop headers that proxies must remove.

The Keep-Alive header suggests how long an idle HTTP/1.1 connection is kept open and how many requests it may carry.

The Upgrade header asks to switch the HTTP/1.1 connection to another protocol, most commonly WebSocket.

The Sec-WebSocket-Key header is a random base64 nonce in the WebSocket opening handshake; the server proves it understood the handshake by returning a hash of it in Sec-WebSocket-Accept.

The Expect header asks the server, with the value 100-continue, to approve the request headers before the client sends a large body.

The Alt-Svc header advertises alternative services for the origin — most often that it is also reachable over HTTP/3.

The Priority header signals the urgency (0–7) and incremental-delivery preference of a response, for HTTP/2 and HTTP/3 scheduling.

The Early-Data header is added by an intermediary (value 1) when a request arrived in TLS 1.3 0-RTT early data, which an attacker could replay.

The Alt-Used header tells the server which alternative service (host and port from Alt-Svc) the client is actually connected to.

The Sec-WebSocket-Protocol header negotiates the application subprotocol of a WebSocket: the client lists the ones it speaks, the server picks exactly one.

The Last-Event-ID header is sent by an EventSource when it reconnects, carrying the id of the last server-sent event it received so the server can resume the stream.

The X-Forwarded-For header lists the client IP address and each proxy a request passed through, added by load balancers and reverse proxies.

The X-Forwarded-Proto header tells the backend which protocol (http or https) the client used to reach the proxy.

The X-Forwarded-Host header carries the original Host header the client sent to the proxy.

The X-Real-IP header carries a single client IP address, typically set by nginx from the connection it accepted.

The Forwarded header is the standard way for proxies to pass on the original client address, protocol and host, replacing the X-Forwarded-* headers.

The Via header records the proxies and gateways a message passed through, with their protocol versions.

The Proxy-Status header lets each proxy or CDN on the path say how it handled the response — and, for errors, exactly what went wrong reaching the next hop.

The Max-Forwards header limits how many more times a TRACE or OPTIONS request may be forwarded by proxies, for tracing a request through a chain.

The Location header gives the URL to redirect to (3xx) or the URL of a newly created resource (201).

The Refresh header tells the browser to reload the page or go to another URL after a number of seconds.

The Retry-After header tells the client how long to wait before retrying, as seconds or an HTTP date.

The Allow header lists the HTTP methods the target resource supports.

The Server header names the software that handled the request on the origin server.

The X-Powered-By header advertises the framework or language running the application, such as Express or PHP.

The Date header gives the date and time the message was generated, in GMT.

The Link header expresses typed links to other resources in a header — preload hints, pagination, canonical URLs and more.

The Service-Worker-Allowed header widens the maximum scope a service worker script may register for, beyond the directory the script is served from.

The Prefer header lets the client state optional preferences, such as returning a minimal response or processing asynchronously.

The Idempotency-Key header carries a client-generated unique key so a retried POST or PATCH is processed at most once.

The X-RateLimit-Limit header is one of three conventional headers, with X-RateLimit-Remaining and X-RateLimit-Reset, that tell an API client its request quota, how much is left and when it resets.

The RateLimit-Policy header advertises the quota policies the server enforces — how many quota units each policy allows in what time window.

The RateLimit header reports the quota still available under a policy and how many seconds until it is replenished — the standardised successor to X-RateLimit-*.

The Accept-Patch header advertises which patch document formats the resource accepts with the PATCH method.

The Deprecation header signals that the requested API resource is (or will be) deprecated, with the date as a structured-field timestamp.

The Sunset header gives the date after which a resource is expected to become unavailable.

The X-Requested-With header marks a request as made by JavaScript (value XMLHttpRequest) rather than by a page navigation.

The Server-Timing header reports server-side timings — database, cache, render — that appear in the browser's DevTools network panel.

The Timing-Allow-Origin header lets other origins' scripts see detailed Resource Timing (and Server-Timing) data for this resource.

The Traceparent header propagates a distributed-tracing context — trace ID, parent span ID and flags — between services.

The X-Request-ID header carries a unique ID for a request so its log lines can be correlated across proxies and services.

The Reporting-Endpoints header names URLs where the browser should POST reports — CSP violations, deprecations, crashes.

The Report-To header defined named groups of reporting endpoints as JSON in the first version of the Reporting API; Reporting-Endpoints replaces it.

The NEL header turns on Network Error Logging: the browser reports DNS, TCP, TLS and HTTP failures (and optionally a sample of successes) for the origin.

The Referer header gives the address of the page that linked to or requested the resource — spelled "Referer", a misspelling kept since 1996.

The X-Robots-Tag header gives search-engine indexing directives such as noindex and nofollow for any response, including non-HTML files.

The DNT header was the "Do Not Track" signal (DNT: 1); the standard was abandoned and almost no site honoured it.

The Sec-GPC header is the Global Privacy Control signal (Sec-GPC: 1): the user asks sites not to sell or share their personal data.

The Sec-Browsing-Topics header carried the user's interest topics from Chrome's Topics API (Privacy Sandbox) to ad-tech servers; Chrome is retiring it.

The X-DNS-Prefetch-Control header turns the browser's speculative DNS lookups for links on the page on or off.

Run git reset --soft HEAD~1 to undo the last commit and keep its changes staged; use git reset HEAD~1 to keep them unstaged, or git reset --hard HEAD~1 to throw them away.

Stage the changes and run git commit --amend --no-edit to fold them into the last commit without changing its message.

For the last commit run git commit --amend -m "New message"; for an older one run git rebase -i <commit>~1 and change pick to reword on that line.

Run git restore --staged <file> to unstage a file while keeping your edits; on Git older than 2.23 use git reset HEAD <file>.

Run git restore <file> to throw away unstaged changes to a file, or git restore --staged --worktree <file> to also drop staged ones and return it to the last commit.

Preview with git clean -n -d, then run git clean -f -d to delete untracked files and directories; add -x to also delete ignored files.

Run git revert <commit> to create a new commit that undoes the changes of an earlier one, without rewriting history.

Run git revert -m 1 <merge-commit> to undo a merge, keeping the first parent (the branch you merged into) as the mainline.

Run git reflog to find the commit's hash, then git branch rescue <hash> (or git reset --hard <hash>) to get it back after a bad reset, rebase or amend.

Find the branch's last commit in git reflog (or in the "Deleted branch … (was <hash>)" message) and recreate it with git branch <name> <hash>.

Right after a finished rebase, run git reset --hard ORIG_HEAD; if you have done more since, find the pre-rebase commit in git reflog and reset to it.

Run git reset --hard ORIG_HEAD right after the merge (or git pull) to move the branch back to where it was; use git revert -m 1 if the merge is already pushed.

Run git merge --abort, git rebase --abort or git cherry-pick --abort to cancel the operation and return to the state before it started.

Run git fetch origin, then git reset --hard origin/<branch> to make your local branch identical to the remote one, discarding local commits and changes.

On a shared branch, run git revert <commit> and push the new commit; only on a branch nobody else uses, reset it away and push with --force-with-lease.

All three move the current branch to another commit; --soft keeps the index and files, --mixed (the default) resets the index but keeps files, and --hard resets both, discarding changes.

Run git reset --hard to throw away every staged and unstaged change to tracked files, then git clean -f -d to delete untracked files; git stash push -u is the undoable alternative.

Run git reset --soft HEAD@{1} to put the branch back on the commit as it was before the amend, with the amended changes left staged.

To drop a newly added file, run git rm --cached <file> and git commit --amend --no-edit; to drop only your changes to an existing file, run git reset HEAD~1 -- <file> and amend.

Run git rebase -i HEAD~N and change pick to squash (or fixup) on every commit except the first; alternatively git reset --soft HEAD~N && git commit.

For the last commit run git commit --amend --author="Name <email>" --no-edit; to fix your identity on several commits, rebase with --exec "git commit --amend --no-edit --reset-author".

Run git rebase -i <commit>~1, mark the commit as edit, then git reset HEAD~1 and commit the changes again in pieces before git rebase --continue.

Stage the fix, run git commit --fixup=<commit>, then git rebase -i --autosquash <commit>~1 to merge it into the original commit.

Run git commit --allow-empty -m "Trigger CI" and push it to re-run pipelines without changing any files.

Run git add -p <file> and answer y or n for each hunk to stage only some of a file's changes; press s to split a hunk or e to edit it.

Set git config --global gpg.format ssh and user.signingkey to your public SSH key, then commit.gpgsign true, so every commit is signed and shows as Verified on GitHub or GitLab.

Run git rebase -i HEAD~N, then in the todo list change pick to reword, edit, squash, fixup or drop, or reorder the lines, and save to rewrite the last N commits.

Run git rebase -i <commit>~1 and change pick to drop on that commit, or git rebase --onto <commit>~1 <commit> to cut it out non-interactively; on shared branches use git revert <commit> instead.

Run git commit --amend --no-edit --date="2026-10-01T12:00:00" to change the author date of the last commit; prefix GIT_COMMITTER_DATE="…" to change the committer date too.

Pass -m more than once — git commit -m "Subject" -m "Body paragraph" — and Git joins them as separate paragraphs; or run git commit without -m to write the message in your editor.

End the commit message with a trailer line Co-authored-by: Name <email>, e.g. git commit -m "Fix bug" --trailer "Co-authored-by: Jane Doe <jane@example.com>".

Run git commit --no-verify to bypass the pre-commit and commit-msg hooks, or git push --no-verify to bypass pre-push.

Run git format-patch main..feature to write each commit as a .patch file and git am *.patch to apply them as commits; for uncommitted changes use git diff > change.patch and git apply change.patch.

Run git switch -c <name> to create a branch from the current commit and switch to it (git checkout -b <name> on older Git).

Run git branch -m <old> <new>, push the new name with git push -u origin <new>, then delete the old one with git push origin --delete <old>.

Run git branch -d <name> to delete a branch that is fully merged, or git branch -D <name> to force-delete it.

Run git push origin --delete <branch> to delete a branch on the remote; others then run git fetch --prune to drop their stale copy.

Run git switch <branch> (or git checkout <branch> on Git older than 2.23); git switch - goes back to the previous branch.

Run git fetch, then git switch <branch>: Git creates a local branch tracking origin/<branch> automatically when exactly one remote has it.

Push with git push -u origin <branch> the first time, or run git branch --set-upstream-to=origin/<branch> for an existing branch.

Run git branch for local branches, git branch -a to include remote ones, and git branch -vv to see each branch's upstream and last commit.

Run git branch --merged main --format='%(refname:short)' | grep -vxE 'main|master|develop' | xargs git branch -d to delete every local branch already merged into main.

If you committed to main by mistake, run git branch <new>, then git reset --keep HEAD~N on main, and git switch <new> — the commits now live only on the new branch.

Run git log main..feature to list commits on feature that are not on main, and git diff main...feature to see the changes feature introduced since it branched.

Detached HEAD means you checked out a commit instead of a branch; run git switch - to go back, or git switch -c <new-branch> to keep commits you made there.

Run git branch --show-current (Git 2.22+) to print just the current branch name; it prints nothing when HEAD is detached.

Run git switch --detach <commit> (or git checkout <commit>) to look at an old commit, git switch - to come back, or git switch -c <branch> <commit> to start a branch from it.

Run git fetch --prune, then delete local branches whose upstream shows as [gone]: git for-each-ref --format="%(refname:short) %(upstream:track)" refs/heads | awk '$2 == "[gone]" {print $1}' | xargs gi…

Git stops a switch, checkout or pull that would clobber uncommitted edits; stash them with git stash push, run the command again, then git stash pop — or commit or discard them first.

Run git remote set-url origin <new-url>, for example to switch from HTTPS to SSH or after a repository moved; check it with git remote -v.

Run git remote add <name> <url>, e.g. git remote add upstream https://github.com/original/repo.git, then git fetch <name>.

Add the original repo as upstream, run git fetch upstream, merge or rebase upstream/main into your main, then push to origin.

Use git push --force-with-lease instead of --force: it refuses to overwrite the remote branch if someone else pushed to it since your last fetch.

git fetch downloads new commits and updates remote-tracking branches without touching your work; git pull runs a fetch and then merges (or rebases) into your current branch.

Run git pull --rebase to replay your local commits on top of the upstream ones, or set git config --global pull.rebase true to make it the default.

Run git clone --depth 1 <url> to download only the latest commit, optionally with --branch <branch-or-tag>; use --filter=blob:none for a full-history partial clone.

The remote has commits you don't; run git pull --rebase (or git pull) to integrate them, resolve any conflicts, then git push again.

Run git pull origin main --allow-unrelated-histories (or git merge --allow-unrelated-histories) to merge two repositories that share no common commit.

In the project folder run git init, git add ., git commit -m "Initial commit", git branch -M main, git remote add origin <url> and git push -u origin main.

Use SSH keys, or set a credential helper (git config --global credential.helper osxkeychain on macOS, or Git Credential Manager elsewhere) so HTTPS tokens are stored securely.

Run git remote rename <old> <new> (e.g. git remote rename origin upstream) or git remote remove <name>; check the result with git remote -v.

Run git fetch --prune and then git branch -r to list remote-tracking branches, or git ls-remote --heads origin to ask the server directly.

Use a refspec: git push origin local-name:remote-name pushes your local branch to a remote branch of another name, and git push origin HEAD:remote-name pushes whatever you have checked out.

Git cannot find a local branch called main: either you have no commits yet (commit first) or your branch has another name such as master — check with git branch --show-current and push that name or re…

The server did not accept any SSH key you offered: create one with ssh-keygen -t ed25519, add it to ssh-agent, upload the .pub file to your forge, and test with ssh -T git@github.com.

From your feature branch run git fetch origin and git rebase origin/main, resolve conflicts with git add and git rebase --continue, then push with --force-with-lease.

Run git status to list conflicted files, edit out the <<<<<<< ======= >>>>>>> markers, git add each file, then git commit (merge) or git rebase --continue (rebase).

Run git cherry-pick <commit> to apply the changes of one commit onto the current branch as a new commit; use A^..B for a range.

git merge joins two branches with a merge commit and keeps history exactly as it happened; git rebase replays your commits on top of the other branch for a linear history but rewrites them.

Switch to main, update it, and run git merge <branch>: git switch main, git pull, git merge feature, then git push.

For one file during a conflict run git checkout --ours <file> or --theirs <file>; for a whole merge run git merge -X ours <branch> or -X theirs to resolve every conflicting hunk in that side's favour.

Run git stash push -m "message" (add -u for untracked files) to shelve your changes, and git stash pop to bring them back.

Run git stash push -- <path>… to stash only the listed files, or git stash push --staged to stash only what is staged.

Use the hash printed when it was dropped, or list dangling commits with git fsck --no-reflog, then run git stash apply <hash>.

Run git log --oneline --graph --decorate --all to see every branch's commits as a compact graph.

Run git log -S "text" to find commits that changed how many times a string appears (the "pickaxe"), or git log --grep="text" to search commit messages.

Run git blame <file> (optionally -L 40,60 for a line range) to show the commit, author and date that last changed each line.

Run git show <commit>:<path> to print a file as it was at that commit, or git restore --source=<commit> <path> to bring that version into your working tree.

Find the commit that deleted it with git log --diff-filter=D -- <path>, then run git restore --source=<commit>~1 -- <path>.

Run git diff for unstaged changes, git diff --staged for what will be committed, and git diff HEAD for both together.

Run git bisect start, git bisect bad, git bisect good <known-good-commit>, then test each commit Git checks out (or automate with git bisect run <test-command>) until it names the first bad commit.

Run git show --name-only <commit> for the file names, --name-status to see whether each was added, modified or deleted, or --stat for a summary with line counts.

Run git diff <commit-a> <commit-b> to see what changed from a to b; add -- <path> to limit it to a file, e.g. git diff main feature -- src/app.ts.

Run git rev-list --count HEAD for the number of commits on the current branch, git rev-list --count main..feature for commits on feature not on main, and git shortlog -sn HEAD per author.

Add a .mailmap file at the repository root with lines like Jane Doe <jane@example.com> <jane@old-laptop.local> so git log, git shortlog and git blame show one identity — without rewriting history.

Rotate the secret first, then run git filter-repo --invert-paths --path <file> (or BFG Repo-Cleaner) to rewrite every commit without the file, and force-push all branches and tags.

Run git rm --cached <file> (add -r for a directory), add it to .gitignore, and commit; the file stays on disk but leaves the repository.

.gitignore only affects untracked files: if the file is already tracked, run git rm --cached <file> and commit; use git check-ignore -v <file> to see which rule applies.

Run git mv readme.md README.md; on case-insensitive file systems (macOS, Windows) where that fails, rename via a temporary name: git mv readme.md tmp && git mv tmp README.md.

Add a .gitattributes file with "* text=auto eol=lf" and run git add --renormalize . so the repository stores LF and checkouts are consistent on every OS.

Run git lfs install once, then git lfs track "*.psd" and commit .gitattributes; matching files are stored on the LFS server and replaced by small pointers in Git.

Git has no reliable way to ignore changes to a tracked file: commit a template (config.example.json), untrack the real file with git rm --cached and .gitignore it; git update-index --skip-worktree is …

Clone with git clone --filter=blob:none --sparse <url>, then git sparse-checkout set <dir>… to populate only those directories (Git 2.25+).

Run git update-index --chmod=+x <file> (or git add --chmod=+x <file>) and commit to record the executable bit; set git config core.fileMode false to stop Git reporting permission-only changes.

Pipe git rev-list --objects --all into git cat-file --batch-check='%(objecttype) %(objectname) %(objectsize) %(rest)' and sort by size to list the biggest blobs ever committed, even deleted ones.

Run git ls-files to list tracked files in the index, or git ls-tree -r --name-only HEAD for the files in the last commit; add --others --exclude-standard to ls-files for untracked ones.

Run git archive --format=zip -o app.zip HEAD (or any branch or tag) to export the tracked files of that commit without the .git folder or untracked files.

Run git tag -a v1.2.0 -m "Release 1.2.0" to create an annotated tag on the current commit, then git push origin v1.2.0 to publish it.

Run git tag -d <tag> to delete it locally and git push origin --delete <tag> to delete it on the remote.

Run git push origin <tag> for one tag, or git push --follow-tags to push commits together with the annotated tags that point at them.

Run git switch --detach v1.2.0 to look at the code of a tag, or git switch -c fix-1.2 v1.2.0 to start a branch from it; run git fetch --tags first if the tag is new.

Run git describe --tags --abbrev=0 for the most recent tag reachable from HEAD, or git tag --sort=-v:refname | head -1 for the highest version number.

Run git config --global user.name "Your Name" and git config --global user.email "you@example.com"; omit --global inside a repository to override them just there.

Run git config --global alias.<name> "<command>", e.g. git config --global alias.st status, then use git st.

Clone with git clone --recurse-submodules <url>, or in an existing clone run git submodule update --init --recursive.

Run git worktree add ../app-hotfix hotfix to check out another branch in a separate folder that shares the same repository.

Run git config --global init.defaultBranch main (Git 2.28+) so new repositories start on main; to switch an existing repository, run git branch -m master main, push it with git push -u origin main, ch…

Run git config --list --show-origin to list every setting with the file it comes from, or git config --show-origin --get <key> for a single value.

Run git config --global core.editor "code --wait" (or "nano", "vim", "subl -w") to choose the editor for commit messages and rebases.

Run git maintenance start (Git 2.30+) in the repository to schedule background maintenance, or git gc for a one-off clean-up; check the size with git count-objects -vH.

Run git submodule deinit -f <path>, git rm -f <path>, delete .git/modules/<path>, and commit; git rm also removes the entry from .gitmodules.

Git refuses repositories owned by another user; if you trust it, run git config --global --add safe.directory <path>, or better, give the directory back to yourself with chown.

chmod 000 (---------) removes every permission: the owner, the group and others cannot read, write or execute it (only root can still access it).

chmod 001 (--------x) gives the owner no access, the group no access, and lets others execute.

chmod 002 (-------w-) gives the owner no access, the group no access, and lets others write.

chmod 003 (-------wx) gives the owner no access, the group no access, and lets others write and execute.

chmod 004 (------r--) gives the owner no access, the group no access, and lets others read.

chmod 005 (------r-x) gives the owner no access, the group no access, and lets others read and execute.

chmod 006 (------rw-) gives the owner no access, the group no access, and lets others read and write.

chmod 007 (------rwx) gives the owner no access, the group no access, and lets others read, write and execute.

chmod 010 (-----x---) gives the owner no access, lets the group execute, and gives others no access.

chmod 011 (-----x--x) gives the owner no access, and lets everyone else execute.

chmod 012 (-----x-w-) gives the owner no access, lets the group execute, and others write.

chmod 013 (-----x-wx) gives the owner no access, lets the group execute, and others write and execute.

chmod 014 (-----xr--) gives the owner no access, lets the group execute, and others read.

chmod 015 (-----xr-x) gives the owner no access, lets the group execute, and others read and execute.

chmod 016 (-----xrw-) gives the owner no access, lets the group execute, and others read and write.

chmod 017 (-----xrwx) gives the owner no access, lets the group execute, and others read, write and execute.

chmod 020 (----w----) gives the owner no access, lets the group write, and gives others no access.

chmod 021 (----w---x) gives the owner no access, lets the group write, and others execute.

chmod 022 (----w--w-) gives the owner no access, and lets everyone else write.

chmod 023 (----w--wx) gives the owner no access, lets the group write, and others write and execute.

chmod 024 (----w-r--) gives the owner no access, lets the group write, and others read.

chmod 025 (----w-r-x) gives the owner no access, lets the group write, and others read and execute.

chmod 026 (----w-rw-) gives the owner no access, lets the group write, and others read and write.

chmod 027 (----w-rwx) gives the owner no access, lets the group write, and others read, write and execute.

chmod 030 (----wx---) gives the owner no access, lets the group write and execute, and gives others no access.

chmod 031 (----wx--x) gives the owner no access, lets the group write and execute, and others execute.

chmod 032 (----wx-w-) gives the owner no access, lets the group write and execute, and others write.

chmod 033 (----wx-wx) gives the owner no access, and lets everyone else write and execute.

chmod 034 (----wxr--) gives the owner no access, lets the group write and execute, and others read.

chmod 035 (----wxr-x) gives the owner no access, lets the group write and execute, and others read and execute.

chmod 036 (----wxrw-) gives the owner no access, lets the group write and execute, and others read and write.

chmod 037 (----wxrwx) gives the owner no access, lets the group write and execute, and others read, write and execute.

chmod 040 (---r-----) gives the owner no access, lets the group read, and gives others no access.

chmod 041 (---r----x) gives the owner no access, lets the group read, and others execute.

chmod 042 (---r---w-) gives the owner no access, lets the group read, and others write.

chmod 043 (---r---wx) gives the owner no access, lets the group read, and others write and execute.

chmod 044 (---r--r--) gives the owner no access, and lets everyone else read.

chmod 045 (---r--r-x) gives the owner no access, lets the group read, and others read and execute.

chmod 046 (---r--rw-) gives the owner no access, lets the group read, and others read and write.

chmod 047 (---r--rwx) gives the owner no access, lets the group read, and others read, write and execute.

chmod 050 (---r-x---) gives the owner no access, lets the group read and execute, and gives others no access.

chmod 051 (---r-x--x) gives the owner no access, lets the group read and execute, and others execute.

chmod 052 (---r-x-w-) gives the owner no access, lets the group read and execute, and others write.

chmod 053 (---r-x-wx) gives the owner no access, lets the group read and execute, and others write and execute.

chmod 054 (---r-xr--) gives the owner no access, lets the group read and execute, and others read.

chmod 055 (---r-xr-x) gives the owner no access, and lets everyone else read and execute.

chmod 056 (---r-xrw-) gives the owner no access, lets the group read and execute, and others read and write.

chmod 057 (---r-xrwx) gives the owner no access, lets the group read and execute, and others read, write and execute.

chmod 060 (---rw----) gives the owner no access, lets the group read and write, and gives others no access.

chmod 061 (---rw---x) gives the owner no access, lets the group read and write, and others execute.

chmod 062 (---rw--w-) gives the owner no access, lets the group read and write, and others write.

chmod 063 (---rw--wx) gives the owner no access, lets the group read and write, and others write and execute.

chmod 064 (---rw-r--) gives the owner no access, lets the group read and write, and others read.

chmod 065 (---rw-r-x) gives the owner no access, lets the group read and write, and others read and execute.

chmod 066 (---rw-rw-) gives the owner no access, and lets everyone else read and write.

chmod 067 (---rw-rwx) gives the owner no access, lets the group read and write, and others read, write and execute.

chmod 070 (---rwx---) gives the owner no access, lets the group read, write and execute, and gives others no access.

chmod 071 (---rwx--x) gives the owner no access, lets the group read, write and execute, and others execute.

chmod 072 (---rwx-w-) gives the owner no access, lets the group read, write and execute, and others write.

chmod 073 (---rwx-wx) gives the owner no access, lets the group read, write and execute, and others write and execute.

chmod 074 (---rwxr--) gives the owner no access, lets the group read, write and execute, and others read.

chmod 075 (---rwxr-x) gives the owner no access, lets the group read, write and execute, and others read and execute.

chmod 076 (---rwxrw-) gives the owner no access, lets the group read, write and execute, and others read and write.

chmod 077 (---rwxrwx) gives the owner no access, and lets everyone else read, write and execute.

chmod 100 (--x------) lets the owner execute, and gives everyone else no access.

chmod 101 (--x-----x) lets the owner execute, gives the group no access, and lets others execute.

chmod 102 (--x----w-) lets the owner execute, gives the group no access, and lets others write.

chmod 103 (--x----wx) lets the owner execute, gives the group no access, and lets others write and execute.

chmod 104 (--x---r--) lets the owner execute, gives the group no access, and lets others read.

chmod 105 (--x---r-x) lets the owner execute, gives the group no access, and lets others read and execute.

chmod 106 (--x---rw-) lets the owner execute, gives the group no access, and lets others read and write.

chmod 107 (--x---rwx) lets the owner execute, gives the group no access, and lets others read, write and execute.

chmod 110 (--x--x---) lets the owner execute, the group execute, and gives others no access.

chmod 111 (--x--x--x) lets everyone — the owner, the group and all other users — execute.

chmod 112 (--x--x-w-) lets the owner execute, the group execute, and others write.

chmod 113 (--x--x-wx) lets the owner execute, the group execute, and others write and execute.

chmod 114 (--x--xr--) lets the owner execute, the group execute, and others read.

chmod 115 (--x--xr-x) lets the owner execute, the group execute, and others read and execute.

chmod 116 (--x--xrw-) lets the owner execute, the group execute, and others read and write.

chmod 117 (--x--xrwx) lets the owner execute, the group execute, and others read, write and execute.

chmod 120 (--x-w----) lets the owner execute, the group write, and gives others no access.

chmod 121 (--x-w---x) lets the owner execute, the group write, and others execute.

chmod 122 (--x-w--w-) lets the owner execute, and everyone else write.

chmod 123 (--x-w--wx) lets the owner execute, the group write, and others write and execute.

chmod 124 (--x-w-r--) lets the owner execute, the group write, and others read.

chmod 125 (--x-w-r-x) lets the owner execute, the group write, and others read and execute.

chmod 126 (--x-w-rw-) lets the owner execute, the group write, and others read and write.

chmod 127 (--x-w-rwx) lets the owner execute, the group write, and others read, write and execute.

chmod 130 (--x-wx---) lets the owner execute, the group write and execute, and gives others no access.

chmod 131 (--x-wx--x) lets the owner execute, the group write and execute, and others execute.

chmod 132 (--x-wx-w-) lets the owner execute, the group write and execute, and others write.

chmod 133 (--x-wx-wx) lets the owner execute, and everyone else write and execute.

chmod 134 (--x-wxr--) lets the owner execute, the group write and execute, and others read.

chmod 135 (--x-wxr-x) lets the owner execute, the group write and execute, and others read and execute.

chmod 136 (--x-wxrw-) lets the owner execute, the group write and execute, and others read and write.

chmod 137 (--x-wxrwx) lets the owner execute, the group write and execute, and others read, write and execute.

chmod 140 (--xr-----) lets the owner execute, the group read, and gives others no access.

chmod 141 (--xr----x) lets the owner execute, the group read, and others execute.

chmod 142 (--xr---w-) lets the owner execute, the group read, and others write.

chmod 143 (--xr---wx) lets the owner execute, the group read, and others write and execute.

chmod 144 (--xr--r--) lets the owner execute, and everyone else read.

chmod 145 (--xr--r-x) lets the owner execute, the group read, and others read and execute.

chmod 146 (--xr--rw-) lets the owner execute, the group read, and others read and write.

chmod 147 (--xr--rwx) lets the owner execute, the group read, and others read, write and execute.

chmod 150 (--xr-x---) lets the owner execute, the group read and execute, and gives others no access.

chmod 151 (--xr-x--x) lets the owner execute, the group read and execute, and others execute.

chmod 152 (--xr-x-w-) lets the owner execute, the group read and execute, and others write.

chmod 153 (--xr-x-wx) lets the owner execute, the group read and execute, and others write and execute.

chmod 154 (--xr-xr--) lets the owner execute, the group read and execute, and others read.

chmod 155 (--xr-xr-x) lets the owner execute, and everyone else read and execute.

chmod 156 (--xr-xrw-) lets the owner execute, the group read and execute, and others read and write.

chmod 157 (--xr-xrwx) lets the owner execute, the group read and execute, and others read, write and execute.

chmod 160 (--xrw----) lets the owner execute, the group read and write, and gives others no access.

chmod 161 (--xrw---x) lets the owner execute, the group read and write, and others execute.

chmod 162 (--xrw--w-) lets the owner execute, the group read and write, and others write.

chmod 163 (--xrw--wx) lets the owner execute, the group read and write, and others write and execute.

chmod 164 (--xrw-r--) lets the owner execute, the group read and write, and others read.

chmod 165 (--xrw-r-x) lets the owner execute, the group read and write, and others read and execute.

chmod 166 (--xrw-rw-) lets the owner execute, and everyone else read and write.

chmod 167 (--xrw-rwx) lets the owner execute, the group read and write, and others read, write and execute.

chmod 170 (--xrwx---) lets the owner execute, the group read, write and execute, and gives others no access.

chmod 171 (--xrwx--x) lets the owner execute, the group read, write and execute, and others execute.

chmod 172 (--xrwx-w-) lets the owner execute, the group read, write and execute, and others write.

chmod 173 (--xrwx-wx) lets the owner execute, the group read, write and execute, and others write and execute.

chmod 174 (--xrwxr--) lets the owner execute, the group read, write and execute, and others read.

chmod 175 (--xrwxr-x) lets the owner execute, the group read, write and execute, and others read and execute.

chmod 176 (--xrwxrw-) lets the owner execute, the group read, write and execute, and others read and write.

chmod 177 (--xrwxrwx) lets the owner execute, and everyone else read, write and execute.

chmod 200 (-w-------) lets the owner write, and gives everyone else no access.

chmod 201 (-w------x) lets the owner write, gives the group no access, and lets others execute.

chmod 202 (-w-----w-) lets the owner write, gives the group no access, and lets others write.

chmod 203 (-w-----wx) lets the owner write, gives the group no access, and lets others write and execute.

chmod 204 (-w----r--) lets the owner write, gives the group no access, and lets others read.

chmod 205 (-w----r-x) lets the owner write, gives the group no access, and lets others read and execute.

chmod 206 (-w----rw-) lets the owner write, gives the group no access, and lets others read and write.

chmod 207 (-w----rwx) lets the owner write, gives the group no access, and lets others read, write and execute.

chmod 210 (-w---x---) lets the owner write, the group execute, and gives others no access.

chmod 211 (-w---x--x) lets the owner write, and everyone else execute.

chmod 212 (-w---x-w-) lets the owner write, the group execute, and others write.

chmod 213 (-w---x-wx) lets the owner write, the group execute, and others write and execute.

chmod 214 (-w---xr--) lets the owner write, the group execute, and others read.

chmod 215 (-w---xr-x) lets the owner write, the group execute, and others read and execute.

chmod 216 (-w---xrw-) lets the owner write, the group execute, and others read and write.

chmod 217 (-w---xrwx) lets the owner write, the group execute, and others read, write and execute.

chmod 220 (-w--w----) lets the owner write, the group write, and gives others no access.

chmod 221 (-w--w---x) lets the owner write, the group write, and others execute.

chmod 222 (-w--w--w-) lets everyone — the owner, the group and all other users — write.

chmod 223 (-w--w--wx) lets the owner write, the group write, and others write and execute.

chmod 224 (-w--w-r--) lets the owner write, the group write, and others read.

chmod 225 (-w--w-r-x) lets the owner write, the group write, and others read and execute.

chmod 226 (-w--w-rw-) lets the owner write, the group write, and others read and write.

chmod 227 (-w--w-rwx) lets the owner write, the group write, and others read, write and execute.

chmod 230 (-w--wx---) lets the owner write, the group write and execute, and gives others no access.

chmod 231 (-w--wx--x) lets the owner write, the group write and execute, and others execute.

chmod 232 (-w--wx-w-) lets the owner write, the group write and execute, and others write.

chmod 233 (-w--wx-wx) lets the owner write, and everyone else write and execute.

chmod 234 (-w--wxr--) lets the owner write, the group write and execute, and others read.

chmod 235 (-w--wxr-x) lets the owner write, the group write and execute, and others read and execute.

chmod 236 (-w--wxrw-) lets the owner write, the group write and execute, and others read and write.

chmod 237 (-w--wxrwx) lets the owner write, the group write and execute, and others read, write and execute.

chmod 240 (-w-r-----) lets the owner write, the group read, and gives others no access.

chmod 241 (-w-r----x) lets the owner write, the group read, and others execute.

chmod 242 (-w-r---w-) lets the owner write, the group read, and others write.

chmod 243 (-w-r---wx) lets the owner write, the group read, and others write and execute.

chmod 244 (-w-r--r--) lets the owner write, and everyone else read.

chmod 245 (-w-r--r-x) lets the owner write, the group read, and others read and execute.

chmod 246 (-w-r--rw-) lets the owner write, the group read, and others read and write.

chmod 247 (-w-r--rwx) lets the owner write, the group read, and others read, write and execute.

chmod 250 (-w-r-x---) lets the owner write, the group read and execute, and gives others no access.

chmod 251 (-w-r-x--x) lets the owner write, the group read and execute, and others execute.

chmod 252 (-w-r-x-w-) lets the owner write, the group read and execute, and others write.

chmod 253 (-w-r-x-wx) lets the owner write, the group read and execute, and others write and execute.

chmod 254 (-w-r-xr--) lets the owner write, the group read and execute, and others read.

chmod 255 (-w-r-xr-x) lets the owner write, and everyone else read and execute.

chmod 256 (-w-r-xrw-) lets the owner write, the group read and execute, and others read and write.

chmod 257 (-w-r-xrwx) lets the owner write, the group read and execute, and others read, write and execute.

chmod 260 (-w-rw----) lets the owner write, the group read and write, and gives others no access.

chmod 261 (-w-rw---x) lets the owner write, the group read and write, and others execute.

chmod 262 (-w-rw--w-) lets the owner write, the group read and write, and others write.

chmod 263 (-w-rw--wx) lets the owner write, the group read and write, and others write and execute.

chmod 264 (-w-rw-r--) lets the owner write, the group read and write, and others read.

chmod 265 (-w-rw-r-x) lets the owner write, the group read and write, and others read and execute.

chmod 266 (-w-rw-rw-) lets the owner write, and everyone else read and write.

chmod 267 (-w-rw-rwx) lets the owner write, the group read and write, and others read, write and execute.

chmod 270 (-w-rwx---) lets the owner write, the group read, write and execute, and gives others no access.

chmod 271 (-w-rwx--x) lets the owner write, the group read, write and execute, and others execute.

chmod 272 (-w-rwx-w-) lets the owner write, the group read, write and execute, and others write.

chmod 273 (-w-rwx-wx) lets the owner write, the group read, write and execute, and others write and execute.

chmod 274 (-w-rwxr--) lets the owner write, the group read, write and execute, and others read.

chmod 275 (-w-rwxr-x) lets the owner write, the group read, write and execute, and others read and execute.

chmod 276 (-w-rwxrw-) lets the owner write, the group read, write and execute, and others read and write.

chmod 277 (-w-rwxrwx) lets the owner write, and everyone else read, write and execute.

chmod 300 (-wx------) lets the owner write and execute, and gives everyone else no access.

chmod 301 (-wx-----x) lets the owner write and execute, gives the group no access, and lets others execute.

chmod 302 (-wx----w-) lets the owner write and execute, gives the group no access, and lets others write.

chmod 303 (-wx----wx) lets the owner write and execute, gives the group no access, and lets others write and execute.

chmod 304 (-wx---r--) lets the owner write and execute, gives the group no access, and lets others read.

chmod 305 (-wx---r-x) lets the owner write and execute, gives the group no access, and lets others read and execute.

chmod 306 (-wx---rw-) lets the owner write and execute, gives the group no access, and lets others read and write.

chmod 307 (-wx---rwx) lets the owner write and execute, gives the group no access, and lets others read, write and execute.

chmod 310 (-wx--x---) lets the owner write and execute, the group execute, and gives others no access.

chmod 311 (-wx--x--x) lets the owner write and execute, and everyone else execute.

chmod 312 (-wx--x-w-) lets the owner write and execute, the group execute, and others write.

chmod 313 (-wx--x-wx) lets the owner write and execute, the group execute, and others write and execute.

chmod 314 (-wx--xr--) lets the owner write and execute, the group execute, and others read.

chmod 315 (-wx--xr-x) lets the owner write and execute, the group execute, and others read and execute.

chmod 316 (-wx--xrw-) lets the owner write and execute, the group execute, and others read and write.

chmod 317 (-wx--xrwx) lets the owner write and execute, the group execute, and others read, write and execute.

chmod 320 (-wx-w----) lets the owner write and execute, the group write, and gives others no access.

chmod 321 (-wx-w---x) lets the owner write and execute, the group write, and others execute.

chmod 322 (-wx-w--w-) lets the owner write and execute, and everyone else write.

chmod 323 (-wx-w--wx) lets the owner write and execute, the group write, and others write and execute.

chmod 324 (-wx-w-r--) lets the owner write and execute, the group write, and others read.

chmod 325 (-wx-w-r-x) lets the owner write and execute, the group write, and others read and execute.

chmod 326 (-wx-w-rw-) lets the owner write and execute, the group write, and others read and write.

chmod 327 (-wx-w-rwx) lets the owner write and execute, the group write, and others read, write and execute.

chmod 330 (-wx-wx---) lets the owner write and execute, the group write and execute, and gives others no access.

chmod 331 (-wx-wx--x) lets the owner write and execute, the group write and execute, and others execute.

chmod 332 (-wx-wx-w-) lets the owner write and execute, the group write and execute, and others write.

chmod 333 (-wx-wx-wx) lets everyone — the owner, the group and all other users — write and execute.

chmod 334 (-wx-wxr--) lets the owner write and execute, the group write and execute, and others read.

chmod 335 (-wx-wxr-x) lets the owner write and execute, the group write and execute, and others read and execute.

chmod 336 (-wx-wxrw-) lets the owner write and execute, the group write and execute, and others read and write.

chmod 337 (-wx-wxrwx) lets the owner write and execute, the group write and execute, and others read, write and execute.

chmod 340 (-wxr-----) lets the owner write and execute, the group read, and gives others no access.

chmod 341 (-wxr----x) lets the owner write and execute, the group read, and others execute.

chmod 342 (-wxr---w-) lets the owner write and execute, the group read, and others write.

chmod 343 (-wxr---wx) lets the owner write and execute, the group read, and others write and execute.

chmod 344 (-wxr--r--) lets the owner write and execute, and everyone else read.

chmod 345 (-wxr--r-x) lets the owner write and execute, the group read, and others read and execute.

chmod 346 (-wxr--rw-) lets the owner write and execute, the group read, and others read and write.

chmod 347 (-wxr--rwx) lets the owner write and execute, the group read, and others read, write and execute.

chmod 350 (-wxr-x---) lets the owner write and execute, the group read and execute, and gives others no access.

chmod 351 (-wxr-x--x) lets the owner write and execute, the group read and execute, and others execute.

chmod 352 (-wxr-x-w-) lets the owner write and execute, the group read and execute, and others write.

chmod 353 (-wxr-x-wx) lets the owner write and execute, the group read and execute, and others write and execute.

chmod 354 (-wxr-xr--) lets the owner write and execute, the group read and execute, and others read.

chmod 355 (-wxr-xr-x) lets the owner write and execute, and everyone else read and execute.

chmod 356 (-wxr-xrw-) lets the owner write and execute, the group read and execute, and others read and write.

chmod 357 (-wxr-xrwx) lets the owner write and execute, the group read and execute, and others read, write and execute.

chmod 360 (-wxrw----) lets the owner write and execute, the group read and write, and gives others no access.

chmod 361 (-wxrw---x) lets the owner write and execute, the group read and write, and others execute.

chmod 362 (-wxrw--w-) lets the owner write and execute, the group read and write, and others write.

chmod 363 (-wxrw--wx) lets the owner write and execute, the group read and write, and others write and execute.

chmod 364 (-wxrw-r--) lets the owner write and execute, the group read and write, and others read.

chmod 365 (-wxrw-r-x) lets the owner write and execute, the group read and write, and others read and execute.

chmod 366 (-wxrw-rw-) lets the owner write and execute, and everyone else read and write.

chmod 367 (-wxrw-rwx) lets the owner write and execute, the group read and write, and others read, write and execute.

chmod 370 (-wxrwx---) lets the owner write and execute, the group read, write and execute, and gives others no access.

chmod 371 (-wxrwx--x) lets the owner write and execute, the group read, write and execute, and others execute.

chmod 372 (-wxrwx-w-) lets the owner write and execute, the group read, write and execute, and others write.

chmod 373 (-wxrwx-wx) lets the owner write and execute, the group read, write and execute, and others write and execute.

chmod 374 (-wxrwxr--) lets the owner write and execute, the group read, write and execute, and others read.

chmod 375 (-wxrwxr-x) lets the owner write and execute, the group read, write and execute, and others read and execute.

chmod 376 (-wxrwxrw-) lets the owner write and execute, the group read, write and execute, and others read and write.

chmod 377 (-wxrwxrwx) lets the owner write and execute, and everyone else read, write and execute.

chmod 400 (r--------) lets the owner read, and gives everyone else no access.

chmod 401 (r-------x) lets the owner read, gives the group no access, and lets others execute.

chmod 402 (r------w-) lets the owner read, gives the group no access, and lets others write.

chmod 403 (r------wx) lets the owner read, gives the group no access, and lets others write and execute.

chmod 404 (r-----r--) lets the owner read, gives the group no access, and lets others read.

chmod 405 (r-----r-x) lets the owner read, gives the group no access, and lets others read and execute.

chmod 406 (r-----rw-) lets the owner read, gives the group no access, and lets others read and write.

chmod 407 (r-----rwx) lets the owner read, gives the group no access, and lets others read, write and execute.

chmod 410 (r----x---) lets the owner read, the group execute, and gives others no access.

chmod 411 (r----x--x) lets the owner read, and everyone else execute.

chmod 412 (r----x-w-) lets the owner read, the group execute, and others write.

chmod 413 (r----x-wx) lets the owner read, the group execute, and others write and execute.

chmod 414 (r----xr--) lets the owner read, the group execute, and others read.

chmod 415 (r----xr-x) lets the owner read, the group execute, and others read and execute.

chmod 416 (r----xrw-) lets the owner read, the group execute, and others read and write.

chmod 417 (r----xrwx) lets the owner read, the group execute, and others read, write and execute.

chmod 420 (r---w----) lets the owner read, the group write, and gives others no access.

chmod 421 (r---w---x) lets the owner read, the group write, and others execute.

chmod 422 (r---w--w-) lets the owner read, and everyone else write.

chmod 423 (r---w--wx) lets the owner read, the group write, and others write and execute.

chmod 424 (r---w-r--) lets the owner read, the group write, and others read.

chmod 425 (r---w-r-x) lets the owner read, the group write, and others read and execute.

chmod 426 (r---w-rw-) lets the owner read, the group write, and others read and write.

chmod 427 (r---w-rwx) lets the owner read, the group write, and others read, write and execute.

chmod 430 (r---wx---) lets the owner read, the group write and execute, and gives others no access.

chmod 431 (r---wx--x) lets the owner read, the group write and execute, and others execute.

chmod 432 (r---wx-w-) lets the owner read, the group write and execute, and others write.

chmod 433 (r---wx-wx) lets the owner read, and everyone else write and execute.

chmod 434 (r---wxr--) lets the owner read, the group write and execute, and others read.

chmod 435 (r---wxr-x) lets the owner read, the group write and execute, and others read and execute.

chmod 436 (r---wxrw-) lets the owner read, the group write and execute, and others read and write.

chmod 437 (r---wxrwx) lets the owner read, the group write and execute, and others read, write and execute.

chmod 440 (r--r-----) lets the owner read, the group read, and gives others no access.

chmod 441 (r--r----x) lets the owner read, the group read, and others execute.

chmod 442 (r--r---w-) lets the owner read, the group read, and others write.

chmod 443 (r--r---wx) lets the owner read, the group read, and others write and execute.

chmod 444 (r--r--r--) lets everyone — the owner, the group and all other users — read.

chmod 445 (r--r--r-x) lets the owner read, the group read, and others read and execute.

chmod 446 (r--r--rw-) lets the owner read, the group read, and others read and write.

chmod 447 (r--r--rwx) lets the owner read, the group read, and others read, write and execute.

chmod 450 (r--r-x---) lets the owner read, the group read and execute, and gives others no access.

chmod 451 (r--r-x--x) lets the owner read, the group read and execute, and others execute.

chmod 452 (r--r-x-w-) lets the owner read, the group read and execute, and others write.

chmod 453 (r--r-x-wx) lets the owner read, the group read and execute, and others write and execute.

chmod 454 (r--r-xr--) lets the owner read, the group read and execute, and others read.

chmod 455 (r--r-xr-x) lets the owner read, and everyone else read and execute.

chmod 456 (r--r-xrw-) lets the owner read, the group read and execute, and others read and write.

chmod 457 (r--r-xrwx) lets the owner read, the group read and execute, and others read, write and execute.

chmod 460 (r--rw----) lets the owner read, the group read and write, and gives others no access.

chmod 461 (r--rw---x) lets the owner read, the group read and write, and others execute.

chmod 462 (r--rw--w-) lets the owner read, the group read and write, and others write.

chmod 463 (r--rw--wx) lets the owner read, the group read and write, and others write and execute.

chmod 464 (r--rw-r--) lets the owner read, the group read and write, and others read.

chmod 465 (r--rw-r-x) lets the owner read, the group read and write, and others read and execute.

chmod 466 (r--rw-rw-) lets the owner read, and everyone else read and write.

chmod 467 (r--rw-rwx) lets the owner read, the group read and write, and others read, write and execute.

chmod 470 (r--rwx---) lets the owner read, the group read, write and execute, and gives others no access.

chmod 471 (r--rwx--x) lets the owner read, the group read, write and execute, and others execute.

chmod 472 (r--rwx-w-) lets the owner read, the group read, write and execute, and others write.

chmod 473 (r--rwx-wx) lets the owner read, the group read, write and execute, and others write and execute.

chmod 474 (r--rwxr--) lets the owner read, the group read, write and execute, and others read.

chmod 475 (r--rwxr-x) lets the owner read, the group read, write and execute, and others read and execute.

chmod 476 (r--rwxrw-) lets the owner read, the group read, write and execute, and others read and write.

chmod 477 (r--rwxrwx) lets the owner read, and everyone else read, write and execute.

chmod 500 (r-x------) lets the owner read and execute, and gives everyone else no access.

chmod 501 (r-x-----x) lets the owner read and execute, gives the group no access, and lets others execute.

chmod 502 (r-x----w-) lets the owner read and execute, gives the group no access, and lets others write.

chmod 503 (r-x----wx) lets the owner read and execute, gives the group no access, and lets others write and execute.

chmod 504 (r-x---r--) lets the owner read and execute, gives the group no access, and lets others read.

chmod 505 (r-x---r-x) lets the owner read and execute, gives the group no access, and lets others read and execute.

chmod 506 (r-x---rw-) lets the owner read and execute, gives the group no access, and lets others read and write.

chmod 507 (r-x---rwx) lets the owner read and execute, gives the group no access, and lets others read, write and execute.

chmod 510 (r-x--x---) lets the owner read and execute, the group execute, and gives others no access.

chmod 511 (r-x--x--x) lets the owner read and execute, and everyone else execute.

chmod 512 (r-x--x-w-) lets the owner read and execute, the group execute, and others write.

chmod 513 (r-x--x-wx) lets the owner read and execute, the group execute, and others write and execute.

chmod 514 (r-x--xr--) lets the owner read and execute, the group execute, and others read.

chmod 515 (r-x--xr-x) lets the owner read and execute, the group execute, and others read and execute.

chmod 516 (r-x--xrw-) lets the owner read and execute, the group execute, and others read and write.

chmod 517 (r-x--xrwx) lets the owner read and execute, the group execute, and others read, write and execute.

chmod 520 (r-x-w----) lets the owner read and execute, the group write, and gives others no access.

chmod 521 (r-x-w---x) lets the owner read and execute, the group write, and others execute.

chmod 522 (r-x-w--w-) lets the owner read and execute, and everyone else write.

chmod 523 (r-x-w--wx) lets the owner read and execute, the group write, and others write and execute.

chmod 524 (r-x-w-r--) lets the owner read and execute, the group write, and others read.

chmod 525 (r-x-w-r-x) lets the owner read and execute, the group write, and others read and execute.

chmod 526 (r-x-w-rw-) lets the owner read and execute, the group write, and others read and write.

chmod 527 (r-x-w-rwx) lets the owner read and execute, the group write, and others read, write and execute.

chmod 530 (r-x-wx---) lets the owner read and execute, the group write and execute, and gives others no access.

chmod 531 (r-x-wx--x) lets the owner read and execute, the group write and execute, and others execute.

chmod 532 (r-x-wx-w-) lets the owner read and execute, the group write and execute, and others write.

chmod 533 (r-x-wx-wx) lets the owner read and execute, and everyone else write and execute.

chmod 534 (r-x-wxr--) lets the owner read and execute, the group write and execute, and others read.

chmod 535 (r-x-wxr-x) lets the owner read and execute, the group write and execute, and others read and execute.

chmod 536 (r-x-wxrw-) lets the owner read and execute, the group write and execute, and others read and write.

chmod 537 (r-x-wxrwx) lets the owner read and execute, the group write and execute, and others read, write and execute.

chmod 540 (r-xr-----) lets the owner read and execute, the group read, and gives others no access.

chmod 541 (r-xr----x) lets the owner read and execute, the group read, and others execute.

chmod 542 (r-xr---w-) lets the owner read and execute, the group read, and others write.

chmod 543 (r-xr---wx) lets the owner read and execute, the group read, and others write and execute.

chmod 544 (r-xr--r--) lets the owner read and execute, and everyone else read.

chmod 545 (r-xr--r-x) lets the owner read and execute, the group read, and others read and execute.

chmod 546 (r-xr--rw-) lets the owner read and execute, the group read, and others read and write.

chmod 547 (r-xr--rwx) lets the owner read and execute, the group read, and others read, write and execute.

chmod 550 (r-xr-x---) lets the owner read and execute, the group read and execute, and gives others no access.

chmod 551 (r-xr-x--x) lets the owner read and execute, the group read and execute, and others execute.

chmod 552 (r-xr-x-w-) lets the owner read and execute, the group read and execute, and others write.

chmod 553 (r-xr-x-wx) lets the owner read and execute, the group read and execute, and others write and execute.

chmod 554 (r-xr-xr--) lets the owner read and execute, the group read and execute, and others read.

chmod 555 (r-xr-xr-x) lets everyone — the owner, the group and all other users — read and execute.

chmod 556 (r-xr-xrw-) lets the owner read and execute, the group read and execute, and others read and write.

chmod 557 (r-xr-xrwx) lets the owner read and execute, the group read and execute, and others read, write and execute.

chmod 560 (r-xrw----) lets the owner read and execute, the group read and write, and gives others no access.

chmod 561 (r-xrw---x) lets the owner read and execute, the group read and write, and others execute.

chmod 562 (r-xrw--w-) lets the owner read and execute, the group read and write, and others write.

chmod 563 (r-xrw--wx) lets the owner read and execute, the group read and write, and others write and execute.

chmod 564 (r-xrw-r--) lets the owner read and execute, the group read and write, and others read.

chmod 565 (r-xrw-r-x) lets the owner read and execute, the group read and write, and others read and execute.

chmod 566 (r-xrw-rw-) lets the owner read and execute, and everyone else read and write.

chmod 567 (r-xrw-rwx) lets the owner read and execute, the group read and write, and others read, write and execute.

chmod 570 (r-xrwx---) lets the owner read and execute, the group read, write and execute, and gives others no access.

chmod 571 (r-xrwx--x) lets the owner read and execute, the group read, write and execute, and others execute.

chmod 572 (r-xrwx-w-) lets the owner read and execute, the group read, write and execute, and others write.

chmod 573 (r-xrwx-wx) lets the owner read and execute, the group read, write and execute, and others write and execute.

chmod 574 (r-xrwxr--) lets the owner read and execute, the group read, write and execute, and others read.

chmod 575 (r-xrwxr-x) lets the owner read and execute, the group read, write and execute, and others read and execute.

chmod 576 (r-xrwxrw-) lets the owner read and execute, the group read, write and execute, and others read and write.

chmod 577 (r-xrwxrwx) lets the owner read and execute, and everyone else read, write and execute.

chmod 600 (rw-------) lets the owner read and write, and gives everyone else no access.

chmod 601 (rw------x) lets the owner read and write, gives the group no access, and lets others execute.

chmod 602 (rw-----w-) lets the owner read and write, gives the group no access, and lets others write.

chmod 603 (rw-----wx) lets the owner read and write, gives the group no access, and lets others write and execute.

chmod 604 (rw----r--) lets the owner read and write, gives the group no access, and lets others read.

chmod 605 (rw----r-x) lets the owner read and write, gives the group no access, and lets others read and execute.

chmod 606 (rw----rw-) lets the owner read and write, gives the group no access, and lets others read and write.

chmod 607 (rw----rwx) lets the owner read and write, gives the group no access, and lets others read, write and execute.

chmod 610 (rw---x---) lets the owner read and write, the group execute, and gives others no access.

chmod 611 (rw---x--x) lets the owner read and write, and everyone else execute.

chmod 612 (rw---x-w-) lets the owner read and write, the group execute, and others write.

chmod 613 (rw---x-wx) lets the owner read and write, the group execute, and others write and execute.

chmod 614 (rw---xr--) lets the owner read and write, the group execute, and others read.

chmod 615 (rw---xr-x) lets the owner read and write, the group execute, and others read and execute.

chmod 616 (rw---xrw-) lets the owner read and write, the group execute, and others read and write.

chmod 617 (rw---xrwx) lets the owner read and write, the group execute, and others read, write and execute.

chmod 620 (rw--w----) lets the owner read and write, the group write, and gives others no access.

chmod 621 (rw--w---x) lets the owner read and write, the group write, and others execute.

chmod 622 (rw--w--w-) lets the owner read and write, and everyone else write.

chmod 623 (rw--w--wx) lets the owner read and write, the group write, and others write and execute.

chmod 624 (rw--w-r--) lets the owner read and write, the group write, and others read.

chmod 625 (rw--w-r-x) lets the owner read and write, the group write, and others read and execute.

chmod 626 (rw--w-rw-) lets the owner read and write, the group write, and others read and write.

chmod 627 (rw--w-rwx) lets the owner read and write, the group write, and others read, write and execute.

chmod 630 (rw--wx---) lets the owner read and write, the group write and execute, and gives others no access.

chmod 631 (rw--wx--x) lets the owner read and write, the group write and execute, and others execute.

chmod 632 (rw--wx-w-) lets the owner read and write, the group write and execute, and others write.

chmod 633 (rw--wx-wx) lets the owner read and write, and everyone else write and execute.

chmod 634 (rw--wxr--) lets the owner read and write, the group write and execute, and others read.

chmod 635 (rw--wxr-x) lets the owner read and write, the group write and execute, and others read and execute.

chmod 636 (rw--wxrw-) lets the owner read and write, the group write and execute, and others read and write.

chmod 637 (rw--wxrwx) lets the owner read and write, the group write and execute, and others read, write and execute.

chmod 640 (rw-r-----) lets the owner read and write, the group read, and gives others no access.

chmod 641 (rw-r----x) lets the owner read and write, the group read, and others execute.

chmod 642 (rw-r---w-) lets the owner read and write, the group read, and others write.

chmod 643 (rw-r---wx) lets the owner read and write, the group read, and others write and execute.

chmod 644 (rw-r--r--) lets the owner read and write, and everyone else read.

chmod 645 (rw-r--r-x) lets the owner read and write, the group read, and others read and execute.

chmod 646 (rw-r--rw-) lets the owner read and write, the group read, and others read and write.

chmod 647 (rw-r--rwx) lets the owner read and write, the group read, and others read, write and execute.

chmod 650 (rw-r-x---) lets the owner read and write, the group read and execute, and gives others no access.

chmod 651 (rw-r-x--x) lets the owner read and write, the group read and execute, and others execute.

chmod 652 (rw-r-x-w-) lets the owner read and write, the group read and execute, and others write.

chmod 653 (rw-r-x-wx) lets the owner read and write, the group read and execute, and others write and execute.

chmod 654 (rw-r-xr--) lets the owner read and write, the group read and execute, and others read.

chmod 655 (rw-r-xr-x) lets the owner read and write, and everyone else read and execute.

chmod 656 (rw-r-xrw-) lets the owner read and write, the group read and execute, and others read and write.

chmod 657 (rw-r-xrwx) lets the owner read and write, the group read and execute, and others read, write and execute.

chmod 660 (rw-rw----) lets the owner read and write, the group read and write, and gives others no access.

chmod 661 (rw-rw---x) lets the owner read and write, the group read and write, and others execute.

chmod 662 (rw-rw--w-) lets the owner read and write, the group read and write, and others write.

chmod 663 (rw-rw--wx) lets the owner read and write, the group read and write, and others write and execute.

chmod 664 (rw-rw-r--) lets the owner read and write, the group read and write, and others read.

chmod 665 (rw-rw-r-x) lets the owner read and write, the group read and write, and others read and execute.

chmod 666 (rw-rw-rw-) lets everyone — the owner, the group and all other users — read and write.

chmod 667 (rw-rw-rwx) lets the owner read and write, the group read and write, and others read, write and execute.

chmod 670 (rw-rwx---) lets the owner read and write, the group read, write and execute, and gives others no access.

chmod 671 (rw-rwx--x) lets the owner read and write, the group read, write and execute, and others execute.

chmod 672 (rw-rwx-w-) lets the owner read and write, the group read, write and execute, and others write.

chmod 673 (rw-rwx-wx) lets the owner read and write, the group read, write and execute, and others write and execute.

chmod 674 (rw-rwxr--) lets the owner read and write, the group read, write and execute, and others read.

chmod 675 (rw-rwxr-x) lets the owner read and write, the group read, write and execute, and others read and execute.

chmod 676 (rw-rwxrw-) lets the owner read and write, the group read, write and execute, and others read and write.

chmod 677 (rw-rwxrwx) lets the owner read and write, and everyone else read, write and execute.

chmod 700 (rwx------) lets the owner read, write and execute, and gives everyone else no access.

chmod 701 (rwx-----x) lets the owner read, write and execute, gives the group no access, and lets others execute.

chmod 702 (rwx----w-) lets the owner read, write and execute, gives the group no access, and lets others write.

chmod 703 (rwx----wx) lets the owner read, write and execute, gives the group no access, and lets others write and execute.

chmod 704 (rwx---r--) lets the owner read, write and execute, gives the group no access, and lets others read.

chmod 705 (rwx---r-x) lets the owner read, write and execute, gives the group no access, and lets others read and execute.

chmod 706 (rwx---rw-) lets the owner read, write and execute, gives the group no access, and lets others read and write.

chmod 707 (rwx---rwx) lets the owner read, write and execute, gives the group no access, and lets others read, write and execute.

chmod 710 (rwx--x---) lets the owner read, write and execute, the group execute, and gives others no access.

chmod 711 (rwx--x--x) lets the owner read, write and execute, and everyone else execute.

chmod 712 (rwx--x-w-) lets the owner read, write and execute, the group execute, and others write.

chmod 713 (rwx--x-wx) lets the owner read, write and execute, the group execute, and others write and execute.

chmod 714 (rwx--xr--) lets the owner read, write and execute, the group execute, and others read.

chmod 715 (rwx--xr-x) lets the owner read, write and execute, the group execute, and others read and execute.

chmod 716 (rwx--xrw-) lets the owner read, write and execute, the group execute, and others read and write.

chmod 717 (rwx--xrwx) lets the owner read, write and execute, the group execute, and others read, write and execute.

chmod 720 (rwx-w----) lets the owner read, write and execute, the group write, and gives others no access.

chmod 721 (rwx-w---x) lets the owner read, write and execute, the group write, and others execute.

chmod 722 (rwx-w--w-) lets the owner read, write and execute, and everyone else write.

chmod 723 (rwx-w--wx) lets the owner read, write and execute, the group write, and others write and execute.

chmod 724 (rwx-w-r--) lets the owner read, write and execute, the group write, and others read.

chmod 725 (rwx-w-r-x) lets the owner read, write and execute, the group write, and others read and execute.

chmod 726 (rwx-w-rw-) lets the owner read, write and execute, the group write, and others read and write.

chmod 727 (rwx-w-rwx) lets the owner read, write and execute, the group write, and others read, write and execute.

chmod 730 (rwx-wx---) lets the owner read, write and execute, the group write and execute, and gives others no access.

chmod 731 (rwx-wx--x) lets the owner read, write and execute, the group write and execute, and others execute.

chmod 732 (rwx-wx-w-) lets the owner read, write and execute, the group write and execute, and others write.

chmod 733 (rwx-wx-wx) lets the owner read, write and execute, and everyone else write and execute.

chmod 734 (rwx-wxr--) lets the owner read, write and execute, the group write and execute, and others read.

chmod 735 (rwx-wxr-x) lets the owner read, write and execute, the group write and execute, and others read and execute.

chmod 736 (rwx-wxrw-) lets the owner read, write and execute, the group write and execute, and others read and write.

chmod 737 (rwx-wxrwx) lets the owner read, write and execute, the group write and execute, and others read, write and execute.

chmod 740 (rwxr-----) lets the owner read, write and execute, the group read, and gives others no access.

chmod 741 (rwxr----x) lets the owner read, write and execute, the group read, and others execute.

chmod 742 (rwxr---w-) lets the owner read, write and execute, the group read, and others write.

chmod 743 (rwxr---wx) lets the owner read, write and execute, the group read, and others write and execute.

chmod 744 (rwxr--r--) lets the owner read, write and execute, and everyone else read.

chmod 745 (rwxr--r-x) lets the owner read, write and execute, the group read, and others read and execute.

chmod 746 (rwxr--rw-) lets the owner read, write and execute, the group read, and others read and write.

chmod 747 (rwxr--rwx) lets the owner read, write and execute, the group read, and others read, write and execute.

chmod 750 (rwxr-x---) lets the owner read, write and execute, the group read and execute, and gives others no access.

chmod 751 (rwxr-x--x) lets the owner read, write and execute, the group read and execute, and others execute.

chmod 752 (rwxr-x-w-) lets the owner read, write and execute, the group read and execute, and others write.

chmod 753 (rwxr-x-wx) lets the owner read, write and execute, the group read and execute, and others write and execute.

chmod 754 (rwxr-xr--) lets the owner read, write and execute, the group read and execute, and others read.

chmod 755 (rwxr-xr-x) lets the owner read, write and execute, and everyone else read and execute.

chmod 756 (rwxr-xrw-) lets the owner read, write and execute, the group read and execute, and others read and write.

chmod 757 (rwxr-xrwx) lets the owner read, write and execute, the group read and execute, and others read, write and execute.

chmod 760 (rwxrw----) lets the owner read, write and execute, the group read and write, and gives others no access.

chmod 761 (rwxrw---x) lets the owner read, write and execute, the group read and write, and others execute.

chmod 762 (rwxrw--w-) lets the owner read, write and execute, the group read and write, and others write.

chmod 763 (rwxrw--wx) lets the owner read, write and execute, the group read and write, and others write and execute.

chmod 764 (rwxrw-r--) lets the owner read, write and execute, the group read and write, and others read.

chmod 765 (rwxrw-r-x) lets the owner read, write and execute, the group read and write, and others read and execute.

chmod 766 (rwxrw-rw-) lets the owner read, write and execute, and everyone else read and write.

chmod 767 (rwxrw-rwx) lets the owner read, write and execute, the group read and write, and others read, write and execute.

chmod 770 (rwxrwx---) lets the owner read, write and execute, the group read, write and execute, and gives others no access.

chmod 771 (rwxrwx--x) lets the owner read, write and execute, the group read, write and execute, and others execute.

chmod 772 (rwxrwx-w-) lets the owner read, write and execute, the group read, write and execute, and others write.

chmod 773 (rwxrwx-wx) lets the owner read, write and execute, the group read, write and execute, and others write and execute.

chmod 774 (rwxrwxr--) lets the owner read, write and execute, the group read, write and execute, and others read.

chmod 775 (rwxrwxr-x) lets the owner read, write and execute, the group read, write and execute, and others read and execute.

chmod 776 (rwxrwxrw-) lets the owner read, write and execute, the group read, write and execute, and others read and write.

chmod 777 (rwxrwxrwx) lets everyone — the owner, the group and all other users — read, write and execute.

Port 20 is the FTP data channel used in active-mode FTP to transfer file contents and directory listings.

Port 21 is the standard control port for FTP (File Transfer Protocol), used for login and commands.

Port 22 is the standard port for SSH (Secure Shell), used for encrypted remote logins, SFTP/SCP file transfer and port forwarding.

Port 23 is the port for Telnet, an old unencrypted remote-terminal protocol.

Port 25 is the standard SMTP port that mail servers use to relay email to each other.

Port 43 is the port for the WHOIS protocol, used to look up domain and IP registration details.

Port 53 is the standard port for DNS (Domain Name System), used to resolve domain names to IP addresses.

Port 67 is the DHCP server port, on which DHCP servers receive requests from clients asking for an IP address.

Port 68 is the DHCP client port, on which devices receive IP address offers from DHCP servers.

Port 69 is the port for TFTP (Trivial File Transfer Protocol), a simple unauthenticated file transfer used for network booting and device firmware.

Port 80 is the default port for HTTP, the unencrypted web protocol that http:// URLs connect to.

Port 88 is the port for the Kerberos authentication protocol, used by Active Directory domain controllers.

Port 110 is the port for POP3 (Post Office Protocol v3), used by email clients to download mail from a server.

Port 111 is the port for rpcbind (the ONC RPC portmapper), which tells clients which port an RPC service such as NFS is on.

Port 119 is the port for NNTP (Network News Transfer Protocol), used by Usenet newsgroups.

Port 123 is the port for NTP (Network Time Protocol), used to synchronize system clocks.

Port 135 is the Microsoft RPC endpoint mapper port, used by Windows services such as DCOM, WMI and Active Directory.

Port 137 is the NetBIOS Name Service port, used by legacy Windows networking for name resolution.

Port 138 is the NetBIOS Datagram Service port, used by legacy Windows networking for browsing announcements.

Port 139 is the NetBIOS Session Service port, used for SMB file sharing over NetBIOS on older Windows networks.

Port 143 is the port for IMAP (Internet Message Access Protocol), used by email clients to read mail that stays on the server.

Port 161 is the port for SNMP (Simple Network Management Protocol), used to query and monitor network devices.

Port 162 is the SNMP trap port, on which network management systems receive unsolicited alerts from devices.

Port 179 is the port for BGP (Border Gateway Protocol), which routers use to exchange internet routing information.

Port 389 is the port for LDAP (Lightweight Directory Access Protocol), used to query directory services such as Active Directory and OpenLDAP.

Port 443 is the default port for HTTPS — HTTP over TLS — which https:// URLs connect to.

Port 445 is the port for SMB (Server Message Block) over TCP, used for Windows file and printer sharing.

Port 464 is the Kerberos password-change port (kpasswd), used to change and set Kerberos and Active Directory passwords.

Port 465 is the port for SMTP submission over implicit TLS (SMTPS), used by email clients and apps to send mail securely.

Port 500 is the port for IKE (Internet Key Exchange), which negotiates keys for IPsec VPNs.

Port 514 is the traditional port for syslog, used to send log messages to a central log server.

Port 515 is the port for LPD (Line Printer Daemon), a legacy network printing protocol.

Port 520 is the port for RIP (Routing Information Protocol), a simple distance-vector routing protocol.

Port 546 is the DHCPv6 client port, on which IPv6 hosts receive configuration from DHCPv6 servers.

Port 547 is the DHCPv6 server port, on which DHCPv6 servers and relays receive requests from IPv6 clients.

Port 548 is the port for AFP (Apple Filing Protocol), Apple’s legacy file-sharing protocol.

Port 554 is the port for RTSP (Real Time Streaming Protocol), used to control streams from IP cameras and media servers.

Port 587 is the standard mail submission port, used by email clients and applications to send outgoing mail through an SMTP server with STARTTLS and authentication.

Port 623 is the port for IPMI over LAN (RMCP), used for out-of-band server management via BMCs such as iDRAC and iLO.

Port 631 is the port for IPP (Internet Printing Protocol), used by CUPS and modern network printers.

Port 636 is the port for LDAPS — LDAP over implicit TLS — used for encrypted directory queries.

Port 830 is the IANA-assigned port for NETCONF over SSH, the protocol used to configure routers and switches programmatically.

Port 853 is the port for DNS over TLS (DoT), which encrypts DNS queries between a client and its resolver.

Port 873 is the port for the rsync daemon protocol, used for efficient file synchronization.

Port 989 is the data port for FTPS (FTP over implicit TLS).

Port 990 is the control port for FTPS (FTP over implicit TLS).

Port 993 is the port for IMAPS — IMAP over implicit TLS — the standard secure port for reading email.

Port 995 is the port for POP3S — POP3 over implicit TLS — used to download email securely.

Port 1025 is the conventional SMTP port for local mail catchers such as MailHog, Mailpit and MailCatcher (which uses 1025 with its UI on 1080).

Port 1080 is the standard port for SOCKS proxies, which relay arbitrary TCP (and SOCKS5 UDP) traffic.

Port 1194 is the default port for OpenVPN.

Port 1234 is the default port for LM Studio’s local server, which exposes an OpenAI-compatible API for local models.

Port 1313 is the default port for hugo server, the Hugo static-site generator’s live-reload preview server.

Port 1433 is the default port for Microsoft SQL Server database connections.

Port 1434 is the SQL Server Browser port, which tells clients which port a named SQL Server instance is listening on.

Port 1521 is the conventional default port for the Oracle Database listener (TNS).

Port 1701 is the port for L2TP (Layer 2 Tunneling Protocol), usually combined with IPsec for VPNs.

Port 1723 is the port for PPTP (Point-to-Point Tunneling Protocol), an obsolete VPN protocol.

Port 1812 is the port for RADIUS authentication, used by Wi-Fi (WPA-Enterprise), VPNs and network devices to check user credentials.

Port 1813 is the port for RADIUS accounting, which records session start/stop and usage data.

Port 1883 is the standard port for MQTT, the lightweight publish/subscribe messaging protocol used by IoT devices.

Port 1900 is the port for SSDP, the discovery protocol used by UPnP devices such as smart TVs, routers and media servers.

Port 1935 is the default port for RTMP (Real-Time Messaging Protocol), used to push live video to streaming platforms.

Port 2003 is the conventional plaintext port for Graphite’s Carbon receiver, which accepts "metric value timestamp" lines.

Port 2049 is the port for NFS (Network File System), used to mount remote directories on Unix-like systems.

Port 2181 is the conventional client port for Apache ZooKeeper, the coordination service used by older Kafka, Hadoop and others.

Port 2222 is a common alternative port for SSH, used to avoid conflicts with or scans of port 22.

Port 2375 is the port for the unencrypted Docker Engine remote API.

Port 2376 is the port for the Docker Engine remote API secured with TLS.

Port 2377 is the Docker Swarm cluster-management port, used for communication with and between swarm manager nodes.

Port 2379 is the etcd client API port, used by Kubernetes and other systems to read and write the etcd key-value store.

Port 2380 is the etcd peer port, used for replication and Raft consensus between etcd cluster members.

Port 2483 is the IANA-assigned port for Oracle Net (TTC) database connections, an alternative to the traditional listener port 1521.

Port 2484 is the IANA-assigned port for Oracle Net (TTC) database connections over TLS.

Port 3000 is the conventional default port for many web development servers, including Node.js/Express examples, Next.js, Create React App, Rails and Grafana.

Port 3001 is a conventional fallback development port, typically used when port 3000 is already taken.

Port 3050 is the default port for the Firebird (and older InterBase) database server, registered with IANA as "gds_db".

Port 3100 is the default HTTP port for Grafana Loki, the log aggregation system.

Port 3128 is the conventional default port for the Squid caching HTTP proxy.

Port 3268 is the Active Directory Global Catalog port, used for LDAP searches across an entire AD forest.

Port 3269 is the Active Directory Global Catalog port over TLS, used for encrypted forest-wide LDAP searches.

Port 3306 is the default port for MySQL and MariaDB database servers.

Port 3389 is the default port for RDP (Remote Desktop Protocol), used to control Windows machines remotely.

Port 3478 is the standard port for STUN and TURN, which WebRTC uses to discover public addresses and relay media through NATs.

Port 3690 is the port for the Subversion (SVN) svnserve protocol.

Port 3702 is the port for WS-Discovery, the multicast protocol Windows and network devices (printers, scanners, ONVIF IP cameras) use to find each other on a LAN.

Port 4000 is a conventional development port, used by default by the Phoenix framework (mix phx.server) and Jekyll (jekyll serve).

Port 4040 is the default port for the Apache Spark application web UI and for the ngrok agent’s local inspection interface.

Port 4173 is the default port for vite preview, which serves a production Vite build locally.

Port 4190 is the port for ManageSieve, the protocol mail clients use to upload Sieve mail-filtering scripts to a server.

Port 4200 is the default port for the Angular CLI development server (ng serve).

Port 4222 is the default client port for the NATS messaging server.

Port 4317 is the default port for the OpenTelemetry Protocol (OTLP) over gRPC, used to send traces, metrics and logs to a collector.

Port 4318 is the default port for the OpenTelemetry Protocol (OTLP) over HTTP, used to send traces, metrics and logs to a collector.

Port 4321 is the default port for the Astro development and preview servers.

Port 4369 is the port for EPMD (Erlang Port Mapper Daemon), which Erlang/Elixir nodes — including RabbitMQ — use to find each other.

Port 4500 is the port for IPsec NAT traversal, which wraps IPsec ESP traffic in UDP so it can cross NAT devices.

Port 4566 is the default edge port for LocalStack, the local emulator for AWS services.

Port 4739 is the IANA-assigned port for IPFIX (IP Flow Information Export), the standardized successor to Cisco NetFlow v9.

Port 4789 is the IANA-assigned port for VXLAN, which carries Layer 2 overlay networks over UDP.

Port 5000 is the default port for the Flask development server and several other tools, and is also used by macOS AirPlay Receiver.

Port 5001 is a conventional development port, commonly used as an alternative to 5000 and as the default HTTPS port for ASP.NET Core development.

Port 5044 is the conventional port for the Logstash Beats input, which receives logs from Filebeat and other Beats shippers.

Port 5060 is the standard port for SIP (Session Initiation Protocol), used to set up VoIP calls.

Port 5061 is the standard port for SIP over TLS, used for encrypted VoIP call signalling.

Port 5173 is the default port for the Vite development server, used by Vite-based projects such as SvelteKit, Vue and React (Vite) apps.

Port 5222 is the standard port for XMPP (Jabber) client-to-server connections.

Port 5269 is the standard port for XMPP server-to-server federation.

Port 5349 is the standard port for STUN and TURN over TLS, used by WebRTC to relay media through restrictive networks.

Port 5353 is the port for multicast DNS (mDNS), used for zero-configuration discovery of .local hostnames, printers and AirPlay/Chromecast devices.

Port 5355 is the port for LLMNR (Link-Local Multicast Name Resolution), a Windows fallback name-resolution protocol.

Port 5357 is the port for Web Services for Devices (WSDAPI), which Windows uses to talk to printers, scanners and other devices found via WS-Discovery.

Port 5432 is the default port for PostgreSQL database servers.

Port 5500 is the default port for the VS Code "Live Server" extension, which serves static files with live reload.

Port 5552 is the default port for the RabbitMQ Stream protocol.

Port 5555 is the conventional port for Android Debug Bridge over TCP/IP, used for wireless debugging of Android devices.

Port 5601 is the default port for Kibana, the web UI for Elasticsearch.

Port 5671 is the standard port for AMQP over TLS.

Port 5672 is the standard port for AMQP, the messaging protocol used by RabbitMQ and other message brokers.

Port 5683 is the IANA-assigned port for CoAP (Constrained Application Protocol), a lightweight REST-style protocol for IoT devices.

Port 5684 is the IANA-assigned port for CoAP secured with DTLS (coaps://), used by IoT devices and LwM2M device management.

Port 5900 is the default port for VNC (Remote Framebuffer protocol) remote desktop, for display :0.

Port 5984 is the default port for Apache CouchDB’s HTTP API.

Port 5985 is the port for Windows Remote Management (WinRM) over HTTP, used by PowerShell Remoting and Ansible for Windows.

Port 5986 is the port for Windows Remote Management (WinRM) over HTTPS.

Port 6000 is the port for the X Window System (X11) display server, for display :0.

Port 6006 is the default port for TensorBoard, TensorFlow’s training visualization dashboard.

Port 6333 is the default HTTP (REST) port for the Qdrant vector database.

Port 6343 is the IANA-assigned port for sFlow, the sampled traffic-monitoring protocol exported by switches and routers.

Port 6379 is the default port for Redis (and Redis-compatible servers such as Valkey), the in-memory key-value store.

Port 6432 is the default port for PgBouncer, the lightweight connection pooler for PostgreSQL.

Port 6443 is the conventional default port for the Kubernetes API server (kube-apiserver).

Port 6514 is the standard port for syslog over TLS, used to send logs securely.

Port 6653 is the IANA-assigned port for OpenFlow, which software-defined-networking switches use to connect to their controller.

Port 6667 is the most commonly used port for plaintext IRC (Internet Relay Chat) connections.

Port 6697 is the standard port for IRC over TLS.

Port 6881 is the traditional default port for BitTorrent peer connections (range 6881–6889).

Port 7474 is the default HTTP port for the Neo4j graph database and its browser UI.

Port 7687 is the default port for Neo4j’s Bolt protocol, used by drivers to run Cypher queries.

Port 7700 is the default port for the Meilisearch search engine’s HTTP API.

Port 7860 is the default port for Gradio apps, including Stable Diffusion web UI (AUTOMATIC1111) and many Hugging Face demos.

Port 7946 is the Docker Swarm node-discovery port, used by the gossip protocol that keeps track of nodes in an overlay network.

Port 8000 is the conventional default port for many development web servers, including Django’s runserver, python -m http.server and Uvicorn/FastAPI.

Port 8001 is the default port for kubectl proxy, which exposes the Kubernetes API on localhost using your kubeconfig credentials.

Port 8025 is the default web UI port for local email-testing tools MailHog and Mailpit.

Port 8080 is the most common alternative HTTP port, used by proxies, application servers such as Tomcat and Jenkins, and development servers.

Port 8081 is a conventional secondary HTTP port, commonly used by Nexus Repository, React Native’s Metro bundler and as a second app server.

Port 8086 is the default HTTP API port for InfluxDB, the time-series database.

Port 8096 is the default HTTP port for the Jellyfin media server web UI.

Port 8123 is the default port for the Home Assistant web interface.

Port 8125 is the default port for StatsD, the UDP metrics aggregation daemon.

Port 8200 is the default API and UI port for HashiCorp Vault.

Port 8384 is the default port for the Syncthing web GUI.

Port 8443 is the most common alternative HTTPS port, used by admin consoles, Tomcat, Kubernetes dashboards and apps that cannot bind to 443.

Port 8472 is the Linux kernel’s default VXLAN port, used by Flannel’s VXLAN backend for Kubernetes pod networking.

Port 8500 is the default HTTP API and UI port for HashiCorp Consul.

Port 8501 is the default port for Streamlit apps.

Port 8787 is the default port for wrangler dev, the local development server for Cloudflare Workers.

Port 8883 is the standard port for MQTT over TLS, used for encrypted IoT messaging.

Port 8888 is the default port for Jupyter Notebook and JupyterLab servers.

Port 8983 is the default port for the Apache Solr search server and its admin UI.

Port 9000 is a conventional port used by default by PHP-FPM (FastCGI), SonarQube, the MinIO S3 API and Portainer’s legacy HTTP UI.

Port 9001 is a conventional port used for the MinIO web console and the Portainer agent, among others.

Port 9042 is the default native protocol (CQL) port for Apache Cassandra and ScyllaDB.

Port 9050 is the default SOCKS port of the Tor client daemon.

Port 9090 is the default port for the Prometheus server and its web UI.

Port 9091 is the default port for the Prometheus Pushgateway and for the Transmission BitTorrent client’s web UI/RPC.

Port 9092 is the default broker port for Apache Kafka.

Port 9093 is the default port for the Prometheus Alertmanager.

Port 9100 is the port for raw TCP printing (HP JetDirect/AppSocket) and, by convention, the Prometheus node_exporter metrics endpoint.

Port 9104 is the default port of the Prometheus mysqld_exporter, which exposes MySQL server metrics.

Port 9115 is the default port of the Prometheus blackbox_exporter, which probes endpoints over HTTP, TCP, DNS and ICMP.

Port 9121 is the default port of the Prometheus redis_exporter, which exposes Redis metrics.

Port 9182 is the default port of the Prometheus windows_exporter (formerly wmi_exporter), which exposes Windows host metrics.

Port 9187 is the default port of the Prometheus postgres_exporter, which exposes PostgreSQL metrics.

Port 9200 is the default HTTP REST API port for Elasticsearch and OpenSearch.

Port 9229 is the default port for the Node.js inspector (debugger), enabled with node --inspect.

Port 9300 is the default node-to-node transport port for Elasticsearch clusters.

Port 9411 is the default port for the Zipkin distributed-tracing server, its API and UI.

Port 9418 is the port for the native Git protocol (git:// URLs), served by git daemon.

Port 9443 is a conventional alternative HTTPS port, used by default by the Portainer web UI and various admin consoles.

Port 10000 is the default port for Webmin, the web-based Unix/Linux server administration panel.

Port 10250 is the port for the Kubernetes kubelet API on each node.

Port 10256 is the kube-proxy health-check port on Kubernetes nodes, used by load balancers to check node health.

Port 10257 is the secure (HTTPS) port of kube-controller-manager on Kubernetes control-plane nodes.

Port 10259 is the secure (HTTPS) port of kube-scheduler on Kubernetes control-plane nodes.

Port 11211 is the default port for Memcached, the in-memory caching server.

Port 11434 is the default port for the Ollama local LLM server API.

Port 15672 is the default port for the RabbitMQ management web UI and HTTP API.

Port 16686 is the default port for the Jaeger tracing UI and query HTTP API.

Port 19132 is the default port for Minecraft Bedrock Edition servers.

Port 22000 is the default port for Syncthing file-synchronization traffic between devices.

Port 24224 is the default port of Fluentd’s forward input, used by Fluent Bit, Docker’s fluentd log driver and other Fluentd nodes to ship logs.

Port 25565 is the default port for Minecraft Java Edition servers.

Port 25575 is the default RCON (remote console) port for Minecraft Java Edition servers.

Port 25672 is the RabbitMQ inter-node and CLI tools communication port (the Erlang distribution port).

Port 26257 is the default port for CockroachDB SQL client connections and inter-node traffic.

Port 27015 is the default port for Valve Source-engine dedicated game servers (e.g. Counter-Strike) and Steam server queries.

Port 27017 is the default port for MongoDB database servers (mongod and mongos).

Port 32400 is the default port for Plex Media Server.

Port 50051 is the port used by convention in gRPC examples and many gRPC services.

Port 51413 is the default peer port for the Transmission BitTorrent client.

Port 51820 is the conventional default port for WireGuard VPN tunnels.

Port 61613 is the conventional port for STOMP, the simple text messaging protocol supported by ActiveMQ and RabbitMQ.

Port 61616 is the default port for Apache ActiveMQ’s OpenWire protocol, used by JMS clients.

The DNS A record (type 1) maps a host name to an IPv4 address.

The DNS AAAA record (type 28) maps a host name to an IPv6 address.

The DNS PTR record (type 12) maps an IP address back to a host name (reverse DNS), using a name under in-addr.arpa or ip6.arpa.

The DNS CNAME record (type 5) makes one name an alias of another, so resolvers restart the lookup at the target name.

ALIAS is not a real DNS record type but a DNS-provider feature that lets the zone apex behave like a CNAME by resolving the target and serving its A/AAAA records.

The DNS DNAME record (type 39) redirects an entire subtree of the namespace to another domain — every name below the owner is aliased, but not the owner itself.

The DNS MX record (type 15) names the mail servers that accept email for a domain, each with a preference number.

SPF is a TXT record at the domain, starting "v=spf1", that lists which servers may send email using the domain in the envelope sender.

DKIM is a TXT record at <selector>._domainkey.<domain> that publishes the public key receivers use to verify a message's DKIM-Signature header.

DMARC is a TXT record at _dmarc.<domain> that tells receivers what to do with mail failing SPF and DKIM alignment, and where to send reports.

MTA-STS is a TXT record at _mta-sts.<domain> announcing a policy, served over HTTPS, that requires sending servers to use verified TLS when delivering mail to the domain.

TLS-RPT is a TXT record at _smtp._tls.<domain> giving an address where sending servers report TLS negotiation failures for mail to the domain.

BIMI is a TXT record at default._bimi.<domain> that points to an SVG logo (and optionally a mark certificate) for mailbox providers to show next to authenticated mail.

The DNS SRV record (type 33) gives the host and port of a service, with priority and weight, at a name of the form _service._proto.<domain>.

The DNS HTTPS record (type 65) tells browsers how to connect to an HTTPS origin before the first request — supported protocols (ALPN such as h3), alternative endpoints, IP hints and ECH keys — and can…

The DNS SVCB record (type 64) is the general "service binding" record that publishes how to reach a service — endpoints, ports, ALPN protocols and other parameters — for any scheme.

The DNS NAPTR record (type 35) holds regular-expression rewrite rules that map a name to a URI or to further DNS names, used mainly by SIP and ENUM telephone-number lookups.

The DNS URI record (type 256) maps a _service._proto name to one or more target URIs, each with a priority and weight like SRV.

The DNS AFSDB record (type 18) names the database servers of an AFS cell (or a DCE authenticated name server) for the domain.

The DNS TXT record (type 16) stores arbitrary text strings at a name, and is how SPF, DKIM, DMARC, domain verification and ACME challenges are published.

Domain verification is a TXT record with a vendor-issued token (for example google-site-verification=…) that proves to a service you control the domain.

ACME DNS-01 is a TXT record at _acme-challenge.<domain> that proves domain control to a certificate authority such as Let's Encrypt during DNS-01 validation.

GitHub Pages verification is a TXT record at _github-pages-challenge-<user or organization>.<domain> that proves to GitHub you own a custom domain, so no other account can publish a Pages site on it.

AT Protocol handle is a TXT record at _atproto.<handle> containing "did=<DID>" that links a domain-name handle, such as a Bluesky username, to an account identifier.

The DNS HINFO record (type 13) was meant to describe a host's CPU and operating system, and is now mostly used to answer ANY queries minimally.

The DNS RP record (type 17) names the person responsible for a host or domain, as a mailbox written like a domain name plus an optional pointer to a TXT record with more details.

The DNS LOC record (type 29) publishes the latitude, longitude, altitude and size of a host or network.

The DNS CAA record (type 257) lists which certificate authorities are allowed to issue TLS certificates for a domain.

The DNS TLSA record (type 52) pins the TLS certificate or public key a service must present, at _<port>._<proto>.<host>, for DANE validation.

The DNS SSHFP record (type 44) publishes fingerprints of a host's SSH keys so clients can verify the host key through DNSSEC instead of trusting it on first use.

The DNS OPENPGPKEY record (type 61) publishes the OpenPGP public key for an email address in DNS, at a name derived from a hash of the address's local part.

The DNS SMIMEA record (type 53) binds an email address to its S/MIME certificate or public key in DNS, using the same fields as TLSA.

The DNS CERT record (type 37) stores a certificate or certificate revocation list — X.509 (PKIX), OpenPGP or SPKI — or a URL pointing to one.

The DNS DS record (type 43) is published in the parent zone and holds a hash of the child zone's key-signing key, linking the DNSSEC chain of trust from parent to child.

The DNS DNSKEY record (type 48) publishes a zone's DNSSEC public keys, which resolvers use to verify RRSIG signatures.

The DNS RRSIG record (type 46) carries the DNSSEC signature over one set of records (an RRset) of a given name and type.

The DNS NSEC record (type 47) proves that a name or record type does not exist in a signed zone by naming the next existing name and the types present.

The DNS NSEC3 record (type 50) proves non-existence like NSEC, but over hashed names so the zone cannot be trivially enumerated.

The DNS NSEC3PARAM record (type 51) publishes, at the zone apex, the hash algorithm, flags, iterations and salt that authoritative servers use to build NSEC3 denial-of-existence answers.

The DNS CDS record (type 59) is published by a child zone to tell its parent which DS record it wants, so registries can update DNSSEC delegation automatically.

The DNS CDNSKEY record (type 60) is published by a child zone to hand its parent the key-signing key itself, so the parent (or registry) can compute and publish the DS record automatically.

The DNS ZONEMD record (type 63) holds a cryptographic digest of an entire zone's contents so a copy can be verified, used notably by the DNS root zone.

The DNS NS record (type 2) names the authoritative name servers for a zone, and delegates a subdomain to other servers.

The DNS SOA record (type 6) is the single record at the top of every zone holding its primary name server, admin contact, serial number and replication and negative-caching timers.

The DNS CSYNC record (type 62) lets a child zone ask its parent to copy its NS records and glue (A/AAAA) into the delegation automatically.

AXFR (type 252) is the query type a secondary server uses to copy an entire zone from the primary; IXFR (251) transfers only the changes since a serial.

IXFR (type 251) is the query type a secondary server uses to fetch only the changes to a zone since the serial number it already has.

TSIG (type 250) authenticates individual DNS messages — zone transfers and dynamic updates — with a shared-secret HMAC.

OPT (type 41) is a pseudo-record in the additional section of a DNS message that carries EDNS(0) extensions: larger UDP payload sizes, the DNSSEC OK bit, client subnet, cookies and extended errors.

ANY (type 255) is a query type asking for all records at a name — but servers may answer with only a subset, so it cannot be used to list a domain's records.

The cron expression to run a job every minute is * * * * *, which runs once every minute, around the clock.

The cron expression to run a job every 2 minutes is */2 * * * *, which runs at every even minute (0, 2, 4 … 58) of every hour.

The cron expression to run a job every 3 minutes is */3 * * * *, which runs at minutes 0, 3, 6 … 57 of every hour.

The cron expression to run a job every 5 minutes is */5 * * * *, which runs at minutes 0, 5, 10 … 55 of every hour.

The cron expression to run a job every 10 minutes is */10 * * * *, which runs at minutes 0, 10, 20, 30, 40 and 50 of every hour.

The cron expression to run a job every 15 minutes is */15 * * * *, which runs at minutes 0, 15, 30 and 45 of every hour.

The cron expression to run a job every 4 minutes is */4 * * * *, which runs at minutes 0, 4, 8 … 56 of every hour.

The cron expression to run a job every 20 minutes is */20 * * * *, which runs at minutes 0, 20 and 40 of every hour.

The cron expression to run a job every 30 minutes is */30 * * * *, which runs at minutes 0 and 30 of every hour.

The cron expression to run a job every 15 minutes during business hours is */15 9-17 * * 1-5, which runs every 15 minutes from 09:00 to 17:45, Monday through Friday.

The cron expression to run a job every 5 minutes during business hours is */5 9-17 * * 1-5, which runs every 5 minutes from 09:00 to 17:55, Monday through Friday.

The cron expression to run a job every 30 minutes during business hours is */30 9-17 * * 1-5, which runs at :00 and :30 from 09:00 to 17:30, Monday through Friday.

The cron expression to run a job every hour is 0 * * * *, which runs at minute 0 of every hour (00:00, 01:00 … 23:00).

The cron expression to run a job every hour at half past is 30 * * * *, which runs at 30 minutes past every hour (00:30, 01:30 … 23:30).

The cron expression to run a job every 2 hours is 0 */2 * * *, which runs at minute 0 of every even hour (00:00, 02:00 … 22:00).

The cron expression to run a job every 3 hours is 0 */3 * * *, which runs at 00:00, 03:00, 06:00, 09:00, 12:00, 15:00, 18:00 and 21:00.

The cron expression to run a job every 4 hours is 0 */4 * * *, which runs at 00:00, 04:00, 08:00, 12:00, 16:00 and 20:00.

The cron expression to run a job every 6 hours is 0 */6 * * *, which runs at 00:00, 06:00, 12:00 and 18:00.

The cron expression to run a job every 8 hours is 0 */8 * * *, which runs at 00:00, 08:00 and 16:00.

The cron expression to run a job every 12 hours is 0 */12 * * *, which runs at 00:00 and 12:00.

The cron expression to run a job every hour on weekdays is 0 * * * 1-5, which runs at minute 0 of every hour, Monday through Friday.

The cron expression to run a job every hour during business hours is 0 9-17 * * 1-5, which runs at the top of every hour from 09:00 to 17:00, Monday through Friday (9 runs a day).

The cron expression to run a job every day at midnight is 0 0 * * *, which runs once a day at 00:00 (midnight).

The cron expression to run a job every day at 1 AM is 0 1 * * *, which runs once a day at 01:00 (1 AM).

The cron expression to run a job every day at 2 AM is 0 2 * * *, which runs once a day at 02:00 (2 AM).

The cron expression to run a job every day at 3 AM is 0 3 * * *, which runs once a day at 03:00 (3 AM).

The cron expression to run a job every day at 4 AM is 0 4 * * *, which runs once a day at 04:00 (4 AM).

The cron expression to run a job every day at 5 AM is 0 5 * * *, which runs once a day at 05:00 (5 AM).

The cron expression to run a job every day at 6 AM is 0 6 * * *, which runs once a day at 06:00 (6 AM).

The cron expression to run a job every day at 6:30 AM is 30 6 * * *, which runs once a day at 06:30 (6:30 AM).

The cron expression to run a job every day at 7 AM is 0 7 * * *, which runs once a day at 07:00 (7 AM).

The cron expression to run a job every day at 8 AM is 0 8 * * *, which runs once a day at 08:00 (8 AM).

The cron expression to run a job every day at 9 AM is 0 9 * * *, which runs once a day at 09:00 (9 AM).

The cron expression to run a job every day at 10 AM is 0 10 * * *, which runs once a day at 10:00 (10 AM).

The cron expression to run a job every day at 11 AM is 0 11 * * *, which runs once a day at 11:00 (11 AM).

The cron expression to run a job every day at noon is 0 12 * * *, which runs once a day at 12:00 (noon).

The cron expression to run a job every day at 1 PM is 0 13 * * *, which runs once a day at 13:00 (1 PM).

The cron expression to run a job every day at 2 PM is 0 14 * * *, which runs once a day at 14:00 (2 PM).

The cron expression to run a job every day at 3 PM is 0 15 * * *, which runs once a day at 15:00 (3 PM).

The cron expression to run a job every day at 4 PM is 0 16 * * *, which runs once a day at 16:00 (4 PM).

The cron expression to run a job every day at 5 PM is 0 17 * * *, which runs once a day at 17:00 (5 PM).

The cron expression to run a job every day at 6 PM is 0 18 * * *, which runs once a day at 18:00 (6 PM).

The cron expression to run a job every day at 7 PM is 0 19 * * *, which runs once a day at 19:00 (7 PM).

The cron expression to run a job every day at 8 PM is 0 20 * * *, which runs once a day at 20:00 (8 PM).

The cron expression to run a job every day at 9 PM is 0 21 * * *, which runs once a day at 21:00 (9 PM).

The cron expression to run a job every day at 10 PM is 0 22 * * *, which runs once a day at 22:00 (10 PM).

The cron expression to run a job every day at 11 PM is 0 23 * * *, which runs once a day at 23:00 (11 PM).

The cron expression to run a job every day at 11:59 PM is 59 23 * * *, which runs once a day at 23:59 (11:59 PM).

The cron expression to run a job twice a day is 0 0,12 * * *, which runs at 00:00 (midnight) and 12:00 (noon) every day.

The cron expression to run a job every day at 9 AM and 5 PM is 0 9,17 * * *, which runs at 09:00 and 17:00 every day.

The cron expression to run a job every other day is 0 0 */2 * *, which runs at 00:00 on every odd-numbered day of the month (1st, 3rd, 5th … 31st).

The cron expression to run a job every Monday is 0 0 * * 1, which runs once a week at 00:00 (midnight) on Monday.

The cron expression to run a job every Tuesday is 0 0 * * 2, which runs once a week at 00:00 (midnight) on Tuesday.

The cron expression to run a job every Wednesday is 0 0 * * 3, which runs once a week at 00:00 (midnight) on Wednesday.

The cron expression to run a job every Thursday is 0 0 * * 4, which runs once a week at 00:00 (midnight) on Thursday.

The cron expression to run a job every Friday is 0 0 * * 5, which runs once a week at 00:00 (midnight) on Friday.

The cron expression to run a job every Saturday is 0 0 * * 6, which runs once a week at 00:00 (midnight) on Saturday.

The cron expression to run a job every Sunday is 0 0 * * 0, which runs once a week at 00:00 (midnight) on Sunday.

The cron expression to run a job every week is 0 0 * * 0, which runs once a week at 00:00 (midnight) on Sunday.

The cron expression to run a job every Monday at 9 AM is 0 9 * * 1, which runs once a week at 09:00 on Monday.

The cron expression to run a job every Friday at 5 PM is 0 17 * * 5, which runs once a week at 17:00 on Friday.

The cron expression to run a job every weekday is 0 0 * * 1-5, which runs at 00:00 (midnight) Monday through Friday.

The cron expression to run a job every weekday at 9 AM is 0 9 * * 1-5, which runs at 09:00 Monday through Friday.

The cron expression to run a job every weekday at 8 AM is 0 8 * * 1-5, which runs at 08:00 Monday through Friday.

The cron expression to run a job every weekday at 5 PM is 0 17 * * 1-5, which runs at 17:00 Monday through Friday.

The cron expression to run a job every weekday at 6 PM is 0 18 * * 1-5, which runs at 18:00 Monday through Friday.

The cron expression to run a job every Sunday at 2 AM is 0 2 * * 0, which runs once a week at 02:00 on Sunday.

The cron expression to run a job every weekend is 0 0 * * 0,6, which runs at 00:00 (midnight) on Saturday and Sunday.

The cron expression to run a job every weekend at 10 AM is 0 10 * * 0,6, which runs at 10:00 on Saturday and Sunday.

The cron expression to run a job on the first day of every month is 0 0 1 * *, which runs at 00:00 (midnight) on the 1st of every month.

The cron expression to run a job on the first day of every month at 9 AM is 0 9 1 * *, which runs at 09:00 on the 1st of every month.

The cron expression to run a job on the 15th of every month is 0 0 15 * *, which runs at 00:00 (midnight) on the 15th of every month.

The cron expression to run a job twice a month is 0 0 1,15 * *, which runs at 00:00 (midnight) on the 1st and 15th of every month.

Standard cron has no last-day-of-month value, so schedule 0 0 28-31 * * and let the job continue only when tomorrow is the 1st — e.g. 0 0 28-31 * * [ "$(date -d tomorrow +\%d)" = "01" ] && /path/to/jo…

Standard cron cannot say “first Monday” (0 9 1-7 * 1 runs on days 1–7 OR on any Monday), so schedule 0 9 1-7 * * and let the job continue only on Monday — e.g. 0 9 1-7 * * [ "$(date +\%u)" = "1" ] && …

The cron expression to run a job every quarter is 0 0 1 1,4,7,10 *, which runs at 00:00 on the 1st of January, April, July and October.

The cron expression to run a job every 6 months is 0 0 1 1,7 *, which runs at 00:00 on the 1st of January and July.

The cron expression to run a job every year is 0 0 1 1 *, which runs once a year at 00:00 on January 1st.

Cron cannot run a job every 30 seconds — its smallest unit is one minute — so run * * * * * with 2 staggered crontab lines (sleep offsets), or use a systemd timer or a scheduler with a seconds field.

Cron cannot run a job every 20 seconds — its smallest unit is one minute — so run * * * * * with 3 staggered crontab lines (sleep offsets), or use a systemd timer or a scheduler with a seconds field.

Cron cannot run a job every 15 seconds — its smallest unit is one minute — so run * * * * * with 4 staggered crontab lines (sleep offsets), or use a systemd timer or a scheduler with a seconds field.

Cron cannot run a job every 10 seconds — its smallest unit is one minute — so run * * * * * with 6 staggered crontab lines (sleep offsets), or use a systemd timer or a scheduler with a seconds field.

Cron cannot run a job every 5 seconds — its smallest unit is one minute — so run * * * * * with 12 staggered crontab lines (sleep offsets), or use a systemd timer or a scheduler with a seconds field.

The regex for an email address is /^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$/, which accepts a local part, one @, a domain and a top-level domain of two or more letters.

The regex for an http or https URL is /^https?:\/\/(?:[A-Za-z0-9-]+\.)+[A-Za-z]{2,}(?::\d{1,5})?(?:[\/?#]\S*)?$/, which requires an http(s) scheme, a dotted hostname with a TLD, an optional port and a…

The regex for a domain name is /^(?:[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?\.)+[a-z]{2,63}$/i, which checks each label is 1–63 letters, digits or inner hyphens and that the name ends in an alphabetic TLD…

The regex for a MIME type is /^(?:application|audio|font|example|image|message|model|multipart|text|video)\/[a-z0-9][a-z0-9!#$&^_.+-]{0,126}$/i, which requires one of the IANA top-level types, a slash…

The regex for an HTML tag is /<\/?([a-zA-Z][a-zA-Z0-9-]*)\b[^>]*>/g, which finds opening, closing and self-closing tags and captures the tag name.

The regex for an HTML comment is /<!--[\s\S]*?-->/g, which lazily matches from "<!--" to the nearest "-->", across lines.

The regex for a Markdown link is /\[([^\]]+)\]\(([^)\s]+)(?:\s+"([^"]*)")?\)/g, which captures the link text, the URL and an optional quoted title of inline [text](url "title") links.

The regex for a file extension is /\.([A-Za-z0-9]+)$/, which captures the alphanumeric characters after the last dot at the end of a filename.

The regex for a CSS hex color is /^#(?:[0-9a-f]{3,4}|[0-9a-f]{6}|[0-9a-f]{8})$/i, which accepts # followed by 3, 4, 6 or 8 hex digits (the 4- and 8-digit forms carry alpha).

The regex for an IPv4 address is /^(?:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\.){3}(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)$/, which accepts four dot-separated octets from 0 to 255 without leading zeros.

The regex for an IPv4 CIDR block is /^(?:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\.){3}(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\/(?:3[0-2]|[12]?\d)$/, which accepts a valid IPv4 address followed by a /0 to /32 …

The regex for an IPv6 address is /^(?:(?:[0-9a-f]{1,4}:){7}[0-9a-f]{1,4}|(?:[0-9a-f]{1,4}:){1,7}:|(?:[0-9a-f]{1,4}:){1,6}:[0-9a-f]{1,4}|(?:[0-9a-f]{1,4}:){1,5}(?::[0-9a-f]{1,4}){1,2}|(?:[0-9a-f]{1,4}:…

The regex for a MAC address is /^(?:[0-9A-Fa-f]{2}(?::[0-9A-Fa-f]{2}){5}|[0-9A-Fa-f]{2}(?:-[0-9A-Fa-f]{2}){5})$/, which accepts six hex byte pairs separated consistently by colons or by hyphens.

The regex for a TCP/UDP port number is /^(?:6553[0-5]|655[0-2]\d|65[0-4]\d{2}|6[0-4]\d{3}|[1-5]\d{4}|[1-9]\d{0,3}|0)$/, which accepts an integer from 0 to 65535 without leading zeros.

The regex for a UUID (versions 1–8) is /^[0-9a-f]{8}-[0-9a-f]{4}-[1-8][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i, which checks the 8-4-4-4-12 hex layout, a version digit of 1–8 and the RFC 9562 var…

The regex for a ULID is /^[0-7][0-9A-HJKMNP-TV-Z]{25}$/i, which checks for 26 Crockford Base32 characters with a first character of 0–7 so the 48-bit timestamp can't overflow.

The regex for a JSON Web Token is /^eyJ[A-Za-z0-9_-]*\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]*$/, which checks for three base64url segments separated by dots, with a header that begins "eyJ" (base64 for '{"').

The regex for a padded Base64 string is /^(?:[A-Za-z0-9+\/]{4})*(?:[A-Za-z0-9+\/]{2}==|[A-Za-z0-9+\/]{3}=)?$/, which accepts groups of four Base64 characters with correct = padding at the end.

The regex for a hexadecimal string is /^(?:0x)?[0-9a-fA-F]+$/, which accepts one or more hex digits with an optional 0x prefix.

The regex for an MD5 hash is /^[a-f0-9]{32}$/i, which accepts exactly 32 hexadecimal characters.

The regex for a SHA-256 hash is /^[a-f0-9]{64}$/i, which accepts exactly 64 hexadecimal characters.

The regex for a Git commit SHA is /^[0-9a-f]{7,40}$/, which accepts an abbreviated (7+) or full 40-character lowercase SHA-1 object id.

The regex for an AWS ARN is /^arn:(?:aws|aws-cn|aws-us-gov):[a-z0-9-]+:[a-z0-9-]*:(?:\d{12})?:.+$/, which checks the arn:partition:service:region:account-id:resource layout.

The regex for an ISO 8601 date (YYYY-MM-DD) is /^\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[01])$/, which accepts a four-digit year, a month 01–12 and a day 01–31.

The regex for an RFC 3339 (ISO 8601) timestamp is /^\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[01])[Tt ](?:[01]\d|2[0-3]):[0-5]\d:(?:[0-5]\d|60)(?:\.\d+)?(?:[Zz]|[+-](?:[01]\d|2[0-3]):[0-5]\d)$/, whic…

The regex for a 24-hour time is /^(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d)?$/, which accepts HH:MM or HH:MM:SS from 00:00 to 23:59:59.

The regex for a digits-only string is /^\d+$/, which accepts one or more characters 0–9 and nothing else.

The regex for an integer is /^-?(?:0|[1-9]\d*)$/, which accepts an optional minus sign and a whole number without leading zeros.

The regex for a decimal number is /^[+-]?(?:\d+\.?\d*|\.\d+)$/, which accepts an optional sign and digits with an optional decimal point, including shorthand forms such as .5 (no leading zero) and 10.…

The regex for a latitude,longitude pair is /^[-+]?(?:[1-8]?\d(?:\.\d+)?|90(?:\.0+)?),\s*[-+]?(?:180(?:\.0+)?|(?:1[0-7]\d|[1-9]?\d)(?:\.\d+)?)$/, which accepts a latitude from -90 to 90 and a longitude…

The regex for leading and trailing whitespace is /^\s+|\s+$/g, which matches whitespace at the start or the end of the string so it can be replaced with nothing.

The regex for trailing whitespace on each line is /[ \t]+$/gm, which matches spaces and tabs just before every line ending.

The regex for blank lines is /^[ \t]*\r?\n/gm, which matches each empty or whitespace-only line including its line break, so replacing with "" deletes it.

The regex for runs of multiple spaces is / {2,}/g, which matches two or more consecutive spaces so they can be collapsed to one.

The regex for repeated words ("the the") is /\b(\w+)\s+\1\b/gi, which captures a word and uses a backreference to find the same word repeated immediately after it.

The regex for a double-quoted string with escapes is /"(?:[^"\\]|\\.)*"/g, which matches from one double quote to the next unescaped one, allowing backslash escapes inside.

The regex for a hashtag is /\B#[A-Za-z]\w*/g, which finds # followed by a letter and word characters, but not when # is glued to a preceding word.

The regex for non-ASCII characters is /[^\x00-\x7F]/gu, which matches any code point outside the 7-bit ASCII range.

The regex for emoji is /\p{Extended_Pictographic}/gu, which uses the Unicode Extended_Pictographic property (with the u flag) to find emoji characters.

The regex for an alphanumeric string is /^[a-zA-Z0-9]+$/, which accepts one or more ASCII letters and digits only.

The regex for a semantic version (SemVer 2.0.0) is /^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-…

The regex for a URL slug is /^[a-z0-9]+(?:-[a-z0-9]+)*$/, which accepts lowercase letters and digits in words separated by single hyphens.

The regex for a username is /^[a-zA-Z][a-zA-Z0-9_-]{2,15}$/, which accepts 3–16 characters starting with a letter, followed by letters, digits, underscores or hyphens.

The regex for a camelCase identifier is /^[a-z][a-z0-9]*(?:[A-Z][a-z0-9]*)*$/, which accepts a lowercase first word followed by capitalised words with no separators.

The regex for a PascalCase identifier is /^[A-Z][a-z0-9]*(?:[A-Z][a-z0-9]*)*$/, which accepts words that each start with a capital letter and have no separators.

The regex for a snake_case identifier is /^[a-z][a-z0-9]*(?:_[a-z0-9]+)*$/, which accepts lowercase words separated by single underscores.

The regex for a kebab-case identifier is /^[a-z][a-z0-9]*(?:-[a-z0-9]+)*$/, which accepts lowercase words separated by single hyphens, starting with a letter.

The regex for a strong password is /^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[^A-Za-z0-9]).{12,}$/, which uses four lookaheads to require a lowercase letter, an uppercase letter, a digit and a symbol, plus…

The regex for a credit card number is /^(?:4\d{12}(?:\d{3})?|5[1-5]\d{14}|2(?:2(?:2[1-9]|[3-9]\d)|[3-6]\d\d|7(?:[01]\d|20))\d{12}|3[47]\d{13}|6(?:011|5\d\d)\d{12})$/, which checks the issuer prefix an…

The regex for an IBAN (structure only) is /^[A-Z]{2}\d{2}[A-Z0-9]{11,30}$/, which checks the structure: a two-letter country code, two check digits and an 11–30 character account part.

The regex for an E.164 international phone number is /^\+[1-9]\d{1,14}$/, which requires a plus sign, a non-zero country code digit and at most 15 digits in total.

The regex for a US (NANP) phone number is /^(?:\+?1[-. ]?)?\(?([2-9]\d{2})\)?[-. ]?([2-9]\d{2})[-. ]?(\d{4})$/, which accepts common US formats with an optional +1, capturing the area code, exchange a…

The regex for a US ZIP code is /^\d{5}(?:-\d{4})?$/, which accepts five digits with an optional ZIP+4 extension.

The MIME type for .3gp files (3GP video) is video/3gpp.

The MIME type for .3mf files (3MF model) is model/3mf.

The MIME type for .7z files (7-Zip archive) is application/x-7z-compressed.

The MIME type for .aac files (AAC audio) is audio/aac.

The MIME type for .ai files (Adobe Illustrator file) is application/postscript.

The MIME type for .aiff files (AIFF audio) is audio/x-aiff.

The MIME type for .amr files (AMR audio) is audio/amr.

The MIME type for .apk files (Android package) is application/vnd.android.package-archive.

The MIME type for .apng files (Animated PNG) is image/apng.

The MIME type for .asc files (ASCII-armored PGP) is application/pgp-signature.

The MIME type for .atom files (Atom feed) is application/atom+xml.

The MIME type for .au files (Sun/NeXT audio) is audio/basic.

The MIME type for .avi files (AVI video) is video/x-msvideo.

The MIME type for .avif files (AVIF image) is image/avif.

The MIME type for .bin files (Binary data) is application/octet-stream.

The MIME type for .bmp files (BMP image) is image/bmp.

The MIME type for .bz2 files (Bzip2 file) is application/x-bzip2.

The MIME type for .c files (C source) is text/x-c.

The MIME type for .cab files (Windows cabinet) is application/vnd.ms-cab-compressed.

The MIME type for .caf files (Core Audio Format) is audio/x-caf.

The MIME type for .cer files (X.509 certificate) is application/pkix-cert.

The MIME type for .cjs files (CommonJS module) is text/javascript.

The MIME type for .class files (Java class file) is application/java-vm.

The MIME type for .cpio files (cpio archive) is application/x-cpio.

The MIME type for .cpp files (C++ source) is text/x-c.

The MIME type for .crl files (Certificate revocation list) is application/pkix-crl.

The MIME type for .crt files (X.509 certificate) is application/x-x509-ca-cert.

The MIME type for .crx files (Chrome extension) is application/x-chrome-extension.

The MIME type for .css files (CSS stylesheet) is text/css.

The MIME type for .csv files (CSV) is text/csv.

The MIME type for .dae files (COLLADA model) is model/vnd.collada+xml.

The MIME type for .dds files (DirectDraw Surface) is image/vnd.ms-dds.

The MIME type for .deb files (Debian package) is application/vnd.debian.binary-package.

The MIME type for .der files (DER certificate) is application/x-x509-ca-cert.

The MIME type for .djvu files (DjVu document) is image/vnd.djvu.

The MIME type for .dll files (Windows DLL) is application/x-msdownload.

The MIME type for .dmg files (macOS disk image) is application/x-apple-diskimage.

The MIME type for .dng files (DNG raw photo) is image/x-adobe-dng.

The MIME type for .doc files (Word 97–2003 document) is application/msword.

The MIME type for .docm files (Word macro-enabled document) is application/vnd.ms-word.document.macroEnabled.12.

The MIME type for .docx files (Word document) is application/vnd.openxmlformats-officedocument.wordprocessingml.document.

The MIME type for .dtd files (XML DTD) is application/xml-dtd.

The MIME type for .dwg files (AutoCAD drawing) is image/vnd.dwg.

The MIME type for .dxf files (DXF drawing) is image/vnd.dxf.

The MIME type for .emf files (Enhanced Metafile) is image/emf.

The MIME type for .eml files (Email message) is message/rfc822.

The MIME type for .eot files (Embedded OpenType font) is application/vnd.ms-fontobject.

The MIME type for .eps files (Encapsulated PostScript) is application/postscript.

The MIME type for .epub files (EPUB e-book) is application/epub+zip.

The MIME type for .exe files (Windows executable) is application/vnd.microsoft.portable-executable.

The MIME type for .exr files (OpenEXR image) is image/aces.

The MIME type for .flac files (FLAC audio) is audio/flac.

The MIME type for .flv files (Flash video) is video/x-flv.

The MIME type for .geojson files (GeoJSON) is application/geo+json.

The MIME type for .gif files (GIF image) is image/gif.

The MIME type for .glb files (glTF binary) is model/gltf-binary.

The MIME type for .gltf files (glTF) is model/gltf+json.

The MIME type for .gpx files (GPX track) is application/gpx+xml.

The MIME type for .gz files (Gzip file) is application/gzip.

The MIME type for .h files (C/C++ header) is text/x-c.

The MIME type for .heic files (HEIC image) is image/heic.

The MIME type for .heics files (HEIC image sequence) is image/heic-sequence.

The MIME type for .heif files (HEIF image) is image/heif.

The MIME type for .htm files (HTML document) is text/html.

The MIME type for .html files (HTML document) is text/html.

The MIME type for .ico files (ICO icon) is image/vnd.microsoft.icon.

The MIME type for .ics files (iCalendar) is text/calendar.

The MIME type for .img files (Disk image) is application/octet-stream.

The MIME type for .ini files (INI config) is text/plain.

The MIME type for .ipynb files (Jupyter notebook) is application/x-ipynb+json.

The MIME type for .iso files (ISO disk image) is application/x-iso9660-image.

The MIME type for .jar files (Java archive) is application/java-archive.

The MIME type for .java files (Java source) is text/x-java-source.

The MIME type for .jp2 files (JPEG 2000 image) is image/jp2.

The MIME type for .jpeg files (JPEG image) is image/jpeg.

The MIME type for .jpg files (JPEG image) is image/jpeg.

The MIME type for .js files (JavaScript) is text/javascript.

The MIME type for .json files (JSON) is application/json.

The MIME type for .json5 files (JSON5 file) is application/json5.

The MIME type for .jsonl files (JSON Lines) is application/jsonl.

The MIME type for .jsonld files (JSON-LD) is application/ld+json.

The MIME type for .jsx files (JSX source) is text/jsx.

The MIME type for .jxl files (JPEG XL image) is image/jxl.

The MIME type for .key files (Private key) is application/octet-stream.

The MIME type for .kml files (KML) is application/vnd.google-earth.kml+xml.

The MIME type for .kmz files (KMZ) is application/vnd.google-earth.kmz.

The MIME type for .ktx2 files (KTX 2.0 texture) is image/ktx2.

The MIME type for .log files (Log file) is text/plain.

The MIME type for .lua files (Lua script) is text/x-lua.

The MIME type for .m2ts files (MPEG-2 transport stream (Blu-ray/AVCHD)) is video/mp2t.

The MIME type for .m3u files (M3U playlist) is audio/x-mpegurl.

The MIME type for .m3u8 files (HLS playlist) is application/vnd.apple.mpegurl.

The MIME type for .m4a files (M4A audio) is audio/mp4.

The MIME type for .m4v files (M4V video) is video/mp4.

The MIME type for .manifest files (AppCache manifest) is text/cache-manifest.

The MIME type for .map files (Source map) is application/json.

The MIME type for .markdown files (Markdown) is text/markdown.

The MIME type for .mbox files (Mailbox) is application/mbox.

The MIME type for .md files (Markdown) is text/markdown.

The MIME type for .mid files (MIDI) is audio/midi.

The MIME type for .midi files (MIDI) is audio/midi.

The MIME type for .mjs files (JavaScript module) is text/javascript.

The MIME type for .mka files (Matroska audio) is audio/matroska.

The MIME type for .mkv files (Matroska video) is video/matroska.

The MIME type for .mobi files (Mobipocket e-book) is application/x-mobipocket-ebook.

The MIME type for .mov files (QuickTime video) is video/quicktime.

The MIME type for .mp3 files (MP3 audio) is audio/mpeg.

The MIME type for .mp4 files (MP4 video) is video/mp4.

The MIME type for .mpd files (MPEG-DASH manifest) is application/dash+xml.

The MIME type for .mpeg files (MPEG video) is video/mpeg.

The MIME type for .mpg files (MPEG video) is video/mpeg.

The MIME type for .msg files (Outlook message) is application/vnd.ms-outlook.

The MIME type for .msi files (Windows Installer package) is application/x-msdownload.

The MIME type for .mts files (AVCHD video) is video/mp2t.

The MIME type for .mxf files (Material Exchange Format) is application/mxf.

The MIME type for .ndjson files (Newline-delimited JSON) is application/x-ndjson.

The MIME type for .numbers files (Apple Numbers spreadsheet) is application/vnd.apple.numbers.

The MIME type for .obj files (Wavefront OBJ) is model/obj.

The MIME type for .odg files (OpenDocument drawing) is application/vnd.oasis.opendocument.graphics.

The MIME type for .odp files (OpenDocument presentation) is application/vnd.oasis.opendocument.presentation.

The MIME type for .ods files (OpenDocument spreadsheet) is application/vnd.oasis.opendocument.spreadsheet.

The MIME type for .odt files (OpenDocument text) is application/vnd.oasis.opendocument.text.

The MIME type for .oga files (Ogg audio) is audio/ogg.

The MIME type for .ogg files (Ogg audio) is audio/ogg.

The MIME type for .ogv files (Ogg video) is video/ogg.

The MIME type for .opus files (Opus audio) is audio/ogg.

The MIME type for .otf files (OpenType font) is font/otf.

The MIME type for .p10 files (PKCS #10 CSR) is application/pkcs10.

The MIME type for .p12 files (PKCS#12 bundle) is application/x-pkcs12.

The MIME type for .p7b files (PKCS #7 certificate bundle) is application/x-pkcs7-certificates.

The MIME type for .p7s files (PKCS #7 signature) is application/pkcs7-signature.

The MIME type for .pages files (Apple Pages document) is application/vnd.apple.pages.

The MIME type for .parquet files (Apache Parquet file) is application/vnd.apache.parquet.

The MIME type for .pcap files (Packet capture) is application/vnd.tcpdump.pcap.

The MIME type for .pdf files (PDF document) is application/pdf.

The MIME type for .pem files (PEM file) is application/x-pem-file.

The MIME type for .pfx files (PKCS#12 bundle) is application/x-pkcs12.

The MIME type for .php files (PHP script) is application/x-httpd-php.

The MIME type for .pkg files (macOS installer package) is application/octet-stream.

The MIME type for .pl files (Perl script) is application/x-perl.

The MIME type for .png files (PNG image) is image/png.

The MIME type for .ppt files (PowerPoint 97–2003 presentation) is application/vnd.ms-powerpoint.

The MIME type for .pptm files (PowerPoint macro-enabled presentation) is application/vnd.ms-powerpoint.presentation.macroEnabled.12.

The MIME type for .pptx files (PowerPoint presentation) is application/vnd.openxmlformats-officedocument.presentationml.presentation.

The MIME type for .ps files (PostScript) is application/postscript.

The MIME type for .psd files (Photoshop document) is image/vnd.adobe.photoshop.

The MIME type for .py files (Python source) is text/x-python.

The MIME type for .rar files (RAR archive) is application/vnd.rar.

The MIME type for .rdf files (RDF/XML) is application/rdf+xml.

The MIME type for .rpm files (RPM package) is application/x-rpm.

The MIME type for .rss files (RSS feed) is application/rss+xml.

The MIME type for .rtf files (Rich Text Format) is application/rtf.

The MIME type for .scss files (SCSS source) is text/x-scss.

The MIME type for .sh files (Shell script) is application/x-sh.

The MIME type for .sig files (Detached signature) is application/pgp-signature.

The MIME type for .sql files (SQL) is application/sql.

The MIME type for .sqlite files (SQLite database) is application/vnd.sqlite3.

The MIME type for .srt files (SubRip subtitles) is application/x-subrip.

The MIME type for .step files (STEP CAD model) is model/step.

The MIME type for .stl files (STL model) is model/stl.

The MIME type for .svg files (SVG image) is image/svg+xml.

The MIME type for .svgz files (Compressed SVG) is image/svg+xml.

The MIME type for .swf files (Flash movie) is application/x-shockwave-flash.

The MIME type for .tar files (Tar archive) is application/x-tar.

The MIME type for .tex files (TeX/LaTeX source) is application/x-tex.

The MIME type for .tga files (TGA image) is image/x-tga.

The MIME type for .tgz files (Gzipped tarball) is application/gzip.

The MIME type for .tif files (TIFF image) is image/tiff.

The MIME type for .tiff files (TIFF image) is image/tiff.

The MIME type for .toml files (TOML) is application/toml.

The MIME type for .torrent files (BitTorrent file) is application/x-bittorrent.

The MIME type for .ts files (MPEG transport stream) is video/mp2t.

The MIME type for .tsv files (TSV) is text/tab-separated-values.

The MIME type for .ttc files (TrueType/OpenType collection) is font/collection.

The MIME type for .ttf files (TrueType font) is font/ttf.

The MIME type for .ttl files (Turtle (RDF)) is text/turtle.

The MIME type for .txt files (Plain text) is text/plain.

The MIME type for .usdz files (USDZ model) is model/vnd.usdz+zip.

The MIME type for .vcf files (vCard) is text/vcard.

The MIME type for .vob files (DVD video object) is video/x-ms-vob.

The MIME type for .vtt files (WebVTT captions) is text/vtt.

The MIME type for .war files (Java web archive) is application/java-archive.

The MIME type for .wasm files (WebAssembly module) is application/wasm.

The MIME type for .wav files (WAV audio) is audio/wav.

The MIME type for .weba files (WebM audio) is audio/webm.

The MIME type for .webm files (WebM video) is video/webm.

The MIME type for .webmanifest files (Web app manifest) is application/manifest+json.

The MIME type for .webp files (WebP image) is image/webp.

The MIME type for .wma files (Windows Media Audio) is audio/x-ms-wma.

The MIME type for .wmf files (Windows Metafile) is image/wmf.

The MIME type for .wmv files (Windows Media Video) is video/x-ms-wmv.

The MIME type for .woff files (WOFF font) is font/woff.

The MIME type for .woff2 files (WOFF2 font) is font/woff2.

The MIME type for .x3d files (X3D model) is model/x3d+xml.

The MIME type for .xhtml files (XHTML document) is application/xhtml+xml.

The MIME type for .xls files (Excel 97–2003 workbook) is application/vnd.ms-excel.

The MIME type for .xlsm files (Excel macro-enabled workbook) is application/vnd.ms-excel.sheet.macroEnabled.12.

The MIME type for .xlsx files (Excel workbook) is application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.

The MIME type for .xml files (XML) is application/xml.

The MIME type for .xpi files (Firefox add-on) is application/x-xpinstall.

The MIME type for .xsd files (XML Schema) is application/xml.

The MIME type for .xsl files (XSLT stylesheet) is application/xslt+xml.

The MIME type for .xz files (XZ file) is application/x-xz.

The MIME type for .yaml files (YAML) is application/yaml.

The MIME type for .yml files (YAML) is application/yaml.

The MIME type for .zip files (ZIP archive) is application/zip.

The MIME type for .zst files (Zstandard file) is application/zstd.

A /0 CIDR block has subnet mask 0.0.0.0 and contains all 4,294,967,296 IPv4 addresses — it matches any address (the default route).

A /1 CIDR block has subnet mask 128.0.0.0 and contains 2,147,483,648 IP addresses, of which 2,147,483,646 are usable hosts.

A /2 CIDR block has subnet mask 192.0.0.0 and contains 1,073,741,824 IP addresses, of which 1,073,741,822 are usable hosts.

A /3 CIDR block has subnet mask 224.0.0.0 and contains 536,870,912 IP addresses, of which 536,870,910 are usable hosts.

A /4 CIDR block has subnet mask 240.0.0.0 and contains 268,435,456 IP addresses, of which 268,435,454 are usable hosts.

A /5 CIDR block has subnet mask 248.0.0.0 and contains 134,217,728 IP addresses, of which 134,217,726 are usable hosts.

A /6 CIDR block has subnet mask 252.0.0.0 and contains 67,108,864 IP addresses, of which 67,108,862 are usable hosts.

A /7 CIDR block has subnet mask 254.0.0.0 and contains 33,554,432 IP addresses, of which 33,554,430 are usable hosts.

A /8 CIDR block has subnet mask 255.0.0.0 and contains 16,777,216 IP addresses, of which 16,777,214 are usable hosts.

A /9 CIDR block has subnet mask 255.128.0.0 and contains 8,388,608 IP addresses, of which 8,388,606 are usable hosts.

A /10 CIDR block has subnet mask 255.192.0.0 and contains 4,194,304 IP addresses, of which 4,194,302 are usable hosts.

A /11 CIDR block has subnet mask 255.224.0.0 and contains 2,097,152 IP addresses, of which 2,097,150 are usable hosts.

A /12 CIDR block has subnet mask 255.240.0.0 and contains 1,048,576 IP addresses, of which 1,048,574 are usable hosts.

A /13 CIDR block has subnet mask 255.248.0.0 and contains 524,288 IP addresses, of which 524,286 are usable hosts.

A /14 CIDR block has subnet mask 255.252.0.0 and contains 262,144 IP addresses, of which 262,142 are usable hosts.

A /15 CIDR block has subnet mask 255.254.0.0 and contains 131,072 IP addresses, of which 131,070 are usable hosts.

A /16 CIDR block has subnet mask 255.255.0.0 and contains 65,536 IP addresses, of which 65,534 are usable hosts.

A /17 CIDR block has subnet mask 255.255.128.0 and contains 32,768 IP addresses, of which 32,766 are usable hosts.

A /18 CIDR block has subnet mask 255.255.192.0 and contains 16,384 IP addresses, of which 16,382 are usable hosts.

A /19 CIDR block has subnet mask 255.255.224.0 and contains 8,192 IP addresses, of which 8,190 are usable hosts.

A /20 CIDR block has subnet mask 255.255.240.0 and contains 4,096 IP addresses, of which 4,094 are usable hosts.

A /21 CIDR block has subnet mask 255.255.248.0 and contains 2,048 IP addresses, of which 2,046 are usable hosts.

A /22 CIDR block has subnet mask 255.255.252.0 and contains 1,024 IP addresses, of which 1,022 are usable hosts.

A /23 CIDR block has subnet mask 255.255.254.0 and contains 512 IP addresses, of which 510 are usable hosts.

A /24 CIDR block has subnet mask 255.255.255.0 and contains 256 IP addresses, of which 254 are usable hosts.

A /25 CIDR block has subnet mask 255.255.255.128 and contains 128 IP addresses, of which 126 are usable hosts.

A /26 CIDR block has subnet mask 255.255.255.192 and contains 64 IP addresses, of which 62 are usable hosts.

A /27 CIDR block has subnet mask 255.255.255.224 and contains 32 IP addresses, of which 30 are usable hosts.

A /28 CIDR block has subnet mask 255.255.255.240 and contains 16 IP addresses, of which 14 are usable hosts.

A /29 CIDR block has subnet mask 255.255.255.248 and contains 8 IP addresses, of which 6 are usable hosts.

A /30 CIDR block has subnet mask 255.255.255.252 and contains 4 IP addresses, of which 2 are usable hosts.

A /31 CIDR block has subnet mask 255.255.255.254 and contains 2 IP addresses, both usable as hosts on a point-to-point link (RFC 3021).

A /32 CIDR block has subnet mask 255.255.255.255 and contains exactly one IP address — a single host.

SIGHUP (1) is the "hangup" signal, sent when a process loses its controlling terminal and conventionally used to tell a daemon to reload its configuration.

SIGINT (2) is the interrupt signal a terminal sends to the foreground process when you press Ctrl+C.

SIGQUIT (3) is the "quit" signal sent by Ctrl+\; by default it terminates the process and writes a core dump.

SIGILL (4) is raised when the CPU tries to execute an illegal, malformed or privileged instruction.

SIGTRAP (5) is the trace/breakpoint trap used by debuggers to stop a process at a breakpoint.

SIGABRT (6) is the abort signal a process sends itself by calling abort(), usually because a library or runtime detected a fatal internal error.

SIGBUS (7) is a "bus error": the process accessed memory that exists in its address space but cannot be backed by real memory or storage.

SIGFPE (8) is the "floating-point exception" signal, raised on an erroneous arithmetic operation — in practice almost always integer division by zero.

SIGKILL (9) kills a process immediately; it cannot be caught, blocked or ignored, so the process gets no chance to clean up.

SIGUSR1 (10) is a user-defined signal with no fixed meaning: each program decides what it does, and if it installs no handler the process is terminated.

SIGSEGV (11) is a segmentation fault: the process accessed memory it is not allowed to, such as a null or dangling pointer.

SIGUSR2 (12) is the second user-defined signal; like SIGUSR1 its meaning is up to the program and it terminates processes that do not handle it.

SIGPIPE (13) is sent to a process that writes to a pipe or socket whose reading end has been closed ("broken pipe").

SIGALRM (14) is delivered when a real-time timer set with alarm() or setitimer(ITIMER_REAL) expires.

SIGTERM (15) politely asks a process to terminate; it is the default signal of kill and lets the program clean up before exiting.

SIGSTKFLT (16) is a Linux-only "coprocessor stack fault" signal that the kernel defines but never sends on modern hardware.

SIGCHLD (17) notifies a parent process that one of its children has exited, stopped or continued.

SIGCONT (18) resumes a process that was stopped by SIGSTOP, SIGTSTP, SIGTTIN or SIGTTOU.

SIGSTOP (19) freezes (suspends) a process; like SIGKILL it cannot be caught, blocked or ignored.

SIGTSTP (20) is the terminal stop signal sent when you press Ctrl+Z, suspending the foreground job.

SIGTTIN (21) stops a background process that tries to read from its controlling terminal.

SIGTTOU (22) stops a background process that writes to its terminal when the tostop terminal mode is set, or that tries to change terminal settings.

SIGURG (23) signals that urgent (out-of-band) data has arrived on a socket.

SIGXCPU (24) is sent when a process exceeds its soft CPU-time limit (RLIMIT_CPU, ulimit -t).

SIGXFSZ (25) is sent when a process tries to grow a file beyond its file-size limit (RLIMIT_FSIZE, ulimit -f).

SIGVTALRM (26) is delivered when a virtual timer (setitimer ITIMER_VIRTUAL, counting only user-mode CPU time) expires.

SIGPROF (27) is delivered when a profiling timer (setitimer ITIMER_PROF, user + system CPU time) expires.

SIGWINCH (28) tells the foreground process that its terminal window has been resized.

SIGIO (29) announces that asynchronous I/O is possible on a file descriptor set up for signal-driven I/O.

SIGPWR (30) reports a power failure, typically from a UPS monitoring daemon.

SIGSYS (31) is raised for a bad or forbidden system call — today most often a seccomp filter rejecting one.

SIGRTMIN (34–64) marks the start of the real-time signal range: on Linux with glibc SIGRTMIN is 34 and SIGRTMAX is 64, giving 31 application-defined signals that queue and carry data.

SIGEMT (macOS 7) is the "emulator trap" signal, raised by certain hardware traps on some architectures.

SIGINFO (macOS 29) is the BSD/macOS status request sent by Ctrl+T, asking the foreground program to print its progress.

Exit code 0 means success: the command finished and reported no error.

Exit code 1 is the generic "something went wrong" status; what exactly failed is up to each program.

Exit code 2 conventionally means incorrect usage — a bad option, missing argument or syntax error — or "serious trouble" for tools that use 1 as an answer.

Exit code 64 means the command was used incorrectly: wrong number of arguments, a bad flag or bad syntax (sysexits.h EX_USAGE).

Exit code 65 means the input data was incorrect in some way — the command was fine, the data was not (sysexits.h EX_DATAERR).

Exit code 66 means an input file did not exist or was not readable (sysexits.h EX_NOINPUT).

Exit code 67 means the addressee or user specified does not exist (sysexits.h EX_NOUSER).

Exit code 68 means the host specified does not exist — typically a failed hostname lookup (sysexits.h EX_NOHOST).

Exit code 69 means a service is unavailable — a support program or file does not exist, or the catch-all when something does not work and the cause is unknown (sysexits.h EX_UNAVAILABLE).

Exit code 70 means an internal software error — a bug or assertion in the program itself, not an operating-system error (sysexits.h EX_SOFTWARE).

Exit code 71 means an operating-system error, such as being unable to fork or create a pipe (sysexits.h EX_OSERR).

Exit code 72 means a critical operating-system file is missing or has an error, such as /etc/passwd (sysexits.h EX_OSFILE).

Exit code 73 means a user-specified output file cannot be created (sysexits.h EX_CANTCREAT).

Exit code 74 means an error occurred while doing I/O on a file (sysexits.h EX_IOERR).

Exit code 75 means a temporary failure — the request was not done, but retrying later may succeed (sysexits.h EX_TEMPFAIL).

Exit code 76 means the remote system returned something that was "not possible" during a protocol exchange (sysexits.h EX_PROTOCOL).

Exit code 77 means the user lacks sufficient permission to perform the operation (sysexits.h EX_NOPERM) — not file-system permission problems, which use EX_NOINPUT or EX_CANTCREAT.

Exit code 78 means something was found in an unconfigured or misconfigured state (sysexits.h EX_CONFIG).

Exit code 124 is what GNU timeout returns when the command it was running hit the time limit and was sent SIGTERM.

Exit code 125 means the wrapper itself failed rather than the command it runs — docker run and GNU timeout, env, nice, nohup and chroot all use it — and tells git bisect run to skip a commit.

Exit code 126 means the command was found but could not be executed — usually missing execute permission or a file that is not a valid program.

Exit code 127 means the shell could not find the command: it is misspelled, not installed, or not on PATH.

Exit code 128 is most often git's status for a fatal error; it is not a signal exit, because 128 + 0 would mean signal 0, which does not exist.

Exit code 129 means the process was terminated by SIGHUP (signal 1); the shell reports 128 + 1.

Exit code 130 means the process was terminated by SIGINT (signal 2) — almost always because someone pressed Ctrl+C.

Exit code 131 means the process was terminated by SIGQUIT (signal 3); the shell reports 128 + 3.

Exit code 132 means the process was terminated by SIGILL (signal 4); the shell reports 128 + 4.

Exit code 133 means the process was terminated by SIGTRAP (signal 5); the shell reports 128 + 5.

Exit code 134 means the process aborted itself with SIGABRT (signal 6), typically after a failed assertion or a detected memory corruption.

Exit code 135 means the process was terminated by SIGBUS (signal 7); the shell reports 128 + 7.

Exit code 136 means the process was terminated by SIGFPE (signal 8); the shell reports 128 + 8.

Exit code 137 means the process was killed with SIGKILL (signal 9) — most often by the out-of-memory killer or a container memory limit.

Exit code 138 means the process was terminated by SIGUSR1 (signal 10); the shell reports 128 + 10.

Exit code 139 means the process crashed with a segmentation fault (SIGSEGV, signal 11): it accessed memory it was not allowed to.

Exit code 140 means the process was terminated by SIGUSR2 (signal 12); the shell reports 128 + 12.

Exit code 141 means the process was killed by SIGPIPE (signal 13): it wrote to a pipe whose reader had already exited.

Exit code 142 means the process was terminated by SIGALRM (signal 14); the shell reports 128 + 14.

Exit code 143 means the process was terminated by SIGTERM (signal 15) — a normal, polite stop request from kill, docker stop, Kubernetes or systemd.

Exit code 144 means the process was terminated by SIGSTKFLT (signal 16); the shell reports 128 + 16.

Exit code 152 means the process was terminated by SIGXCPU (signal 24); the shell reports 128 + 24.

Exit code 153 means the process was terminated by SIGXFSZ (signal 25); the shell reports 128 + 25.

Exit code 154 means the process was terminated by SIGVTALRM (signal 26); the shell reports 128 + 26.

Exit code 155 means the process was terminated by SIGPROF (signal 27); the shell reports 128 + 27.

Exit code 157 means the process was terminated by SIGIO (signal 29); the shell reports 128 + 29.

Exit code 158 means the process was terminated by SIGPWR (signal 30); the shell reports 128 + 30.

Exit code 159 means the process was terminated by SIGSYS (signal 31); the shell reports 128 + 31.

Exit code 255 is the largest exit status; it usually means a program exited with -1, or that ssh itself (not the remote command) failed.

ansible exit code 2 from ansible-playbook means the playbook ran but at least one task failed on at least one host.

ansible exit code 4 from ansible-playbook means at least one host was unreachable — or, from the CLI, that the playbook or inventory could not be parsed.

cargo exit code 101 means a Rust program panicked: the standard runtime exits with 101 when main panics, so cargo run and cargo test report 101 for panics and failing tests.

curl exit code 1 means the URL uses a scheme this curl build does not support or has disabled.

curl exit code 3 means the URL was malformed — curl could not parse it.

curl exit code 5 means curl could not resolve the host name of the proxy it was told to use.

curl exit code 6 means curl could not resolve the host name — the DNS lookup failed.

curl exit code 7 means curl resolved the host but failed to connect to it.

curl exit code 18 means the transfer ended before the full body arrived: the server announced more bytes than it sent.

curl exit code 22 means the server returned an HTTP status of 400 or above and curl was run with --fail (-f) or --fail-with-body.

curl exit code 23 means curl could not write the received data to its destination.

curl exit code 28 means the operation timed out — either the connection or the whole transfer hit its time limit.

curl exit code 35 means the TLS/SSL handshake failed before any HTTP was exchanged.

curl exit code 47 means curl followed redirects until it hit the --max-redirs limit (50 by default).

curl exit code 52 means the server closed the connection without sending any response.

curl exit code 55 means curl failed while sending network data — the connection broke during the upload or request.

curl exit code 56 means curl failed while receiving network data — the connection broke mid-transfer.

curl exit code 60 means the server's TLS certificate could not be verified against the trusted CA certificates.

curl exit code 77 means curl could not read the CA certificate bundle it was told to use.

curl exit code 92 means an error occurred in the HTTP/2 framing layer for this request's stream.

diff exit code 1 means the inputs are different; 0 means identical and 2 means trouble.

diff exit code 2 means diff could not compare the inputs — a missing or unreadable file, or a bad option — as opposed to 1, which means they differ.

eslint exit code 1 means ESLint ran successfully and found at least one error, or more warnings than --max-warnings allows.

eslint exit code 2 means ESLint could not lint at all — a configuration problem or an internal error — rather than finding lint errors.

git exit code 1 is git's ordinary failure status, and with git diff --exit-code or --quiet it specifically means "there are differences".

git exit code 129 means git rejected the command line — an unknown option or wrong arguments — and printed the usage text.

go exit code 1 from the go command means a build, vet or test step failed — for go test, at least one test failed.

go exit code 2 from a compiled Go program means it died from an unrecovered panic or a fatal runtime error (deadlock, concurrent map write), which the Go runtime reports with exit status 2.

grep exit code 1 means grep ran fine but found no matching lines.

grep exit code 2 means an error occurred — such as an unreadable file or an invalid regex — rather than "no match".

jest exit code 1 means at least one test failed, or Jest found no test files to run (unless --passWithNoTests is given).

kubectl exit code 1 is kubectl's generic error status, and from kubectl diff specifically means differences were found (0 means none, above 1 means kubectl or diff failed).

make exit code 1 from make -q (question mode) means some target is not up to date; make itself never returns 1 otherwise.

make exit code 2 means make encountered errors — a recipe command failed, or a target or makefile is missing.

pytest exit code 1 means tests were collected and run, and some of them failed.

pytest exit code 2 means the test run was interrupted — by Ctrl+C (KeyboardInterrupt) or by errors during collection — before it finished.

pytest exit code 3 means an internal error got in the way — usually a crash inside pytest or one of its plugins.

pytest exit code 4 means pytest was misused: an unknown command-line option, or a file or directory on the command line that does not exist.

pytest exit code 5 means pytest ran but collected no tests at all.

pytest exit code 6 means all tests passed but the run produced more warnings than the --max-warnings limit (pytest 9.1 and later).

rsync exit code 23 means some files could not be transferred, but rsync carried on with the rest.

rsync exit code 24 means some source files disappeared between rsync building its file list and copying them.

systemd exit code 200 in systemctl status ("status=200/CHDIR") means systemd could not change into the unit's WorkingDirectory= before starting it.

systemd exit code 203 in systemctl status ("status=203/EXEC") means systemd failed to execute the unit's ExecStart= program.

systemd exit code 209 in systemctl status ("status=209/STDOUT") means systemd could not set up the unit's standard output before starting it.

systemd exit code 216 in systemctl status ("status=216/GROUP") means systemd could not resolve or switch to the unit's Group= or SupplementaryGroups=.

systemd exit code 217 in systemctl status ("status=217/USER") means systemd could not switch to the User= or Group= configured for the unit.

systemd exit code 226 in systemctl status ("status=226/NAMESPACE") means systemd failed to set up the unit's file-system namespace (sandboxing) before starting it.

terraform exit code 2 from terraform plan -detailed-exitcode means the plan succeeded and contains changes; 0 means no changes and 1 means an error.

test exit code 1 from test or [ … ] means the expression evaluated to false; 0 means true and 2 or more means an error.

test exit code 2 from test or [ … ] means the expression itself was invalid, for example an integer comparison with a non-number.

vitest exit code 1 means at least one test failed, or vitest run found no test files (unless --passWithNoTests is given).

EPERM (errno 1 on Linux) means "operation not permitted": the call needs privileges the process lacks, regardless of file permission bits.

ENOENT (errno 2 on Linux) means "no such file or directory": a path, or a directory on the way to it, does not exist.

ESRCH (errno 3 on Linux) means "no such process": the process or thread ID does not exist (any more).

EINTR (errno 4 on Linux) means a blocking system call was interrupted by a signal handler before it completed.

EIO (errno 5 on Linux) means a low-level input/output error: the device or filesystem failed the read or write.

ENXIO (errno 6 on Linux) means "no such device or address": the file exists but nothing is behind it to talk to.

E2BIG (errno 7 on Linux) means "argument list too long": the arguments plus environment passed to execve exceed the kernel limit.

ENOEXEC (errno 8 on Linux) means "exec format error": the kernel does not recognise the file as something it can execute.

EBADF (errno 9 on Linux) means "bad file descriptor": the descriptor is not open, or not open for that kind of access.

ECHILD (errno 10 on Linux) means "no child processes": wait() or waitpid() found no child to wait for.

EAGAIN (errno 11 on Linux) means "resource temporarily unavailable": the operation would block (non-blocking I/O) or a resource limit was hit for now — EWOULDBLOCK is the same number on Linux and macO…

ENOMEM (errno 12 on Linux) means the kernel could not allocate memory for the request ("Cannot allocate memory").

EACCES (errno 13 on Linux) means "permission denied": file permission bits, an ACL or a security module refused the access.

EFAULT (errno 14 on Linux) means "bad address": a pointer passed to a system call points outside the process’s accessible memory.

ENOTBLK (errno 15 on Linux) means a block device was required, for example by mount, but something else was given.

EBUSY (errno 16 on Linux) means "device or resource busy": something else is using the resource in a way that prevents the operation.

EEXIST (errno 17 on Linux) means "file exists": the call needed the path not to exist, and it does.

EXDEV (errno 18 on Linux) means "invalid cross-device link": rename() or link() was asked to move a file between different filesystems.

ENODEV (errno 19 on Linux) means "no such device": the device or the kind of device needed does not exist.

ENOTDIR (errno 20 on Linux) means "not a directory": a component used as a directory in the path is actually a file.

EISDIR (errno 21 on Linux) means "is a directory": the call needs a file, but the path is a directory.

EINVAL (errno 22 on Linux) means "invalid argument": an argument to the call is out of range or does not make sense for this object.

ENFILE (errno 23 on Linux) means "too many open files in system": the system-wide open-file table is full.

EMFILE (errno 24 on Linux) means "too many open files": the process hit its own open-descriptor limit (RLIMIT_NOFILE).

ENOTTY (errno 25 on Linux) means "inappropriate ioctl for device": a terminal (or device-specific) control call was used on something that is not that device.

ETXTBSY (errno 26 on Linux) means "text file busy": an executable that is running was opened for writing, or a file open for writing was executed.

EFBIG (errno 27 on Linux) means "file too large": the write would grow a file past a size limit.

ENOSPC (errno 28 on Linux) means "no space left on device" — but on Linux it can also mean out of inodes, or out of inotify watches.

ESPIPE (errno 29 on Linux) means "illegal seek": lseek() on a pipe, FIFO, socket or terminal, which cannot seek.

EROFS (errno 30 on Linux) means "read-only file system": a write was attempted on a filesystem mounted read-only.

EMLINK (errno 31 on Linux) means "too many links": a file has reached the filesystem’s maximum hard-link count, or a directory its maximum number of subdirectories.

EPIPE (errno 32 on Linux) means "broken pipe": a write went to a pipe or socket whose reading end has been closed.

EDOM (errno 33 on Linux) means a math function’s argument is outside its domain, such as sqrt(-1) or log(-1) in C.

ERANGE (errno 34 on Linux) means a result is out of range for its type, such as strtol overflow or a math function overflowing.

EDEADLK (errno 35 on Linux) means a lock request would deadlock ("Resource deadlock avoided"); EDEADLOCK is the same number on Linux x86-64 and ARM.

ENAMETOOLONG (errno 36 on Linux) means "file name too long": a path component exceeds NAME_MAX (255 bytes on most Linux filesystems) or the whole path exceeds PATH_MAX (4096).

ENOLCK (errno 37 on Linux) means "no locks available": the system could not take the file lock.

ENOSYS (errno 38 on Linux) means "function not implemented": the kernel (or a sandbox in front of it) does not provide this system call.

ENOTEMPTY (errno 39 on Linux) means "directory not empty": rmdir() or a rename onto a directory needs it to be empty.

ELOOP (errno 40 on Linux) means "too many levels of symbolic links": resolving the path followed a symlink loop or too long a chain.

ENOMSG (errno 42 on Linux) means "no message of desired type": a System V message queue has no matching message.

EIDRM (errno 43 on Linux) means "identifier removed": a System V IPC object was deleted while in use.

ECHRNG (errno 44 on Linux) means "channel number out of range".

EL2NSYNC (errno 45 on Linux) means "level 2 not synchronized".

EL3HLT (errno 46 on Linux) means "level 3 halted".

EL3RST (errno 47 on Linux) means "level 3 reset".

ELNRNG (errno 48 on Linux) means "link number out of range".

EUNATCH (errno 49 on Linux) means "protocol driver not attached".

ENOCSI (errno 50 on Linux) means "no CSI structure available".

EL2HLT (errno 51 on Linux) means "level 2 halted".

EBADE (errno 52 on Linux) means "invalid exchange".

EBADR (errno 53 on Linux) means "invalid request descriptor".

EXFULL (errno 54 on Linux) means "exchange full".

ENOANO (errno 55 on Linux) means "no anode".

EBADRQC (errno 56 on Linux) means "invalid request code".

EBADSLT (errno 57 on Linux) means "invalid slot".

EBFONT (errno 59 on Linux) means "bad font file format".

ENOSTR (errno 60 on Linux) means "device not a stream".

ENODATA (errno 61 on Linux) means "no data available" — on Linux mostly that an extended attribute does not exist.

ETIME (errno 62 on Linux) means "timer expired".

ENOSR (errno 63 on Linux) means "out of streams resources".

ENONET (errno 64 on Linux) means "machine is not on the network".

ENOPKG (errno 65 on Linux) means "package not installed".

EREMOTE (errno 66 on Linux) means "object is remote".

ENOLINK (errno 67 on Linux) means "link has been severed".

EADV (errno 68 on Linux) means "advertise error".

ESRMNT (errno 69 on Linux) means "srmount error".

ECOMM (errno 70 on Linux) means "communication error on send".

EPROTO (errno 71 on Linux) means "protocol error": the other side, or a lower layer, violated the protocol.

EMULTIHOP (errno 72 on Linux) means "multihop attempted".

EDOTDOT (errno 73 on Linux) means "RFS specific error".

EBADMSG (errno 74 on Linux) means "bad message": data failed a format or integrity check; Linux filesystems also use it (as EFSBADCRC) for checksum failures.

EOVERFLOW (errno 75 on Linux) means "value too large for defined data type": a size, offset or ID does not fit the type the caller used.

ENOTUNIQ (errno 76 on Linux) means "name not unique on network".

EBADFD (errno 77 on Linux) means "file descriptor in bad state": the descriptor is valid but its object is not usable now.

EREMCHG (errno 78 on Linux) means "remote address changed".

ELIBACC (errno 79 on Linux) means "cannot access a needed shared library".

ELIBBAD (errno 80 on Linux) means "accessing a corrupted shared library".

ELIBSCN (errno 81 on Linux) means ".lib section in a.out corrupted".

ELIBMAX (errno 82 on Linux) means "attempting to link in too many shared libraries".

ELIBEXEC (errno 83 on Linux) means "cannot exec a shared library directly".

EILSEQ (errno 84 on Linux) means "invalid or incomplete multibyte or wide character": text is not valid in the current character encoding.

ERESTART (errno 85 on Linux) means "interrupted system call should be restarted".

ESTRPIPE (errno 86 on Linux) means "streams pipe error".

EUSERS (errno 87 on Linux) means "too many users".

ENOTSOCK (errno 88 on Linux) means "socket operation on non-socket": a socket call was made on a descriptor that is a file, pipe or something else.

EDESTADDRREQ (errno 89 on Linux) means "destination address required": a send had nowhere to go.

EMSGSIZE (errno 90 on Linux) means "message too long": the datagram or message is larger than the socket allows.

EPROTOTYPE (errno 91 on Linux) means "protocol wrong type for socket": the protocol does not match the socket type.

ENOPROTOOPT (errno 92 on Linux) means "protocol not available": the socket option is unknown at that level.

EPROTONOSUPPORT (errno 93 on Linux) means "protocol not supported": the kernel does not support the requested protocol.

ESOCKTNOSUPPORT (errno 94 on Linux) means "socket type not supported" in this address family.

EOPNOTSUPP (errno 95 on Linux) means "operation not supported"; on Linux ENOTSUP is the same number (95), while macOS gives ENOTSUP 45 and EOPNOTSUPP 102.

EPFNOSUPPORT (errno 96 on Linux) means "protocol family not supported".

EAFNOSUPPORT (errno 97 on Linux) means "address family not supported by protocol": the kernel or socket cannot use that address family.

EADDRINUSE (errno 98 on Linux) means "address already in use": another socket is already bound to that address and port.

EADDRNOTAVAIL (errno 99 on Linux) means "cannot assign requested address": the local address or port cannot be used on this host right now.

ENETDOWN (errno 100 on Linux) means "network is down": the interface needed for the operation is down.

ENETUNREACH (errno 101 on Linux) means "network is unreachable": there is no route to the destination network.

ENETRESET (errno 102 on Linux) means "network dropped connection on reset".

ECONNABORTED (errno 103 on Linux) means "software caused connection abort": the connection was aborted on this side.

ECONNRESET (errno 104 on Linux) means "connection reset by peer": the other side (or something in between) sent a TCP RST and dropped the connection.

ENOBUFS (errno 105 on Linux) means "no buffer space available": the kernel could not allocate a network buffer.

EISCONN (errno 106 on Linux) means "transport endpoint is already connected".

ENOTCONN (errno 107 on Linux) means "transport endpoint is not connected": the operation needs a connected socket.

ESHUTDOWN (errno 108 on Linux) means "cannot send after transport endpoint shutdown".

ETOOMANYREFS (errno 109 on Linux) means "too many references: cannot splice".

ETIMEDOUT (errno 110 on Linux) means "connection timed out": the remote side never answered within the kernel’s retry window.

ECONNREFUSED (errno 111 on Linux) means "connection refused": the host answered, but nothing is listening on that port (it replied with a TCP RST).

EHOSTDOWN (errno 112 on Linux) means "host is down".

EHOSTUNREACH (errno 113 on Linux) means "no route to host": the destination host cannot be reached.

EALREADY (errno 114 on Linux) means "operation already in progress" on a non-blocking socket.

EINPROGRESS (errno 115 on Linux) means "operation now in progress": a non-blocking connect() has started and will finish later — expected, not a failure.

ESTALE (errno 116 on Linux) means "stale file handle": a network filesystem handle refers to a file that no longer exists on the server.

EUCLEAN (errno 117 on Linux) means "structure needs cleaning": the filesystem detected on-disk corruption (the kernel’s EFSCORRUPTED).

ENOTNAM (errno 118 on Linux) means "not a XENIX named type file".

ENAVAIL (errno 119 on Linux) means "no XENIX semaphores available".

EISNAM (errno 120 on Linux) means "is a named type file".

EREMOTEIO (errno 121 on Linux) means "remote I/O error": a device at the other end of a bus or link failed the transfer.

EDQUOT (errno 122 on Linux) means "disk quota exceeded": the user or group has used up its quota on this filesystem.

ENOMEDIUM (errno 123 on Linux) means "no medium found": a removable-media drive is empty.

EMEDIUMTYPE (errno 124 on Linux) means "wrong medium type": the inserted medium is not the kind the operation needs.

ECANCELED (errno 125 on Linux) means "operation canceled": an asynchronous operation was cancelled before it finished.

ENOKEY (errno 126 on Linux) means "required key not available": a needed kernel keyring key is missing.

EKEYEXPIRED (errno 127 on Linux) means "key has expired": a kernel keyring key is past its expiry time.

EKEYREVOKED (errno 128 on Linux) means "key has been revoked": a kernel keyring key was explicitly revoked.

EKEYREJECTED (errno 129 on Linux) means "key was rejected by service": a key lookup was negatively answered.

EOWNERDEAD (errno 130 on Linux) means "owner died": the process or thread holding a robust mutex exited while holding it.

ENOTRECOVERABLE (errno 131 on Linux) means "state not recoverable": a robust mutex was unlocked without being marked consistent after its owner died.

ERFKILL (errno 132 on Linux) means "operation not possible due to RF-kill": the radio is blocked.

EHWPOISON (errno 133 on Linux) means "memory page has hardware error": the page was marked poisoned after an uncorrectable memory error.

EFTYPE (errno 134 on Linux) means "wrong file type for the intended operation".

ASCII 0 is NUL (Null), the string terminator in C — hex 0x00, octal 000, binary 00000000.

ASCII 1 is SOH (Start of Heading) — hex 0x01, octal 001, binary 00000001.

ASCII 2 is STX (Start of Text) — hex 0x02, octal 002, binary 00000010.

ASCII 3 is ETX (End of Text), the byte Ctrl+C produces — hex 0x03, octal 003, binary 00000011.

ASCII 4 is EOT (End of Transmission), the byte Ctrl+D produces — hex 0x04, octal 004, binary 00000100.

ASCII 5 is ENQ (Enquiry) — hex 0x05, octal 005, binary 00000101.

ASCII 6 is ACK (Acknowledge) — hex 0x06, octal 006, binary 00000110.

ASCII 7 is BEL (Bell), the terminal bell — hex 0x07, octal 007, binary 00000111.

ASCII 8 is BS (Backspace) — hex 0x08, octal 010, binary 00001000.

ASCII 9 is HT (Horizontal Tab), the tab character — hex 0x09, octal 011, binary 00001001.

ASCII 10 is LF (Line Feed), the newline character on Unix, Linux and macOS — hex 0x0A, octal 012, binary 00001010.

ASCII 11 is VT (Vertical Tab) — hex 0x0B, octal 013, binary 00001011.

ASCII 12 is FF (Form Feed) — hex 0x0C, octal 014, binary 00001100.

ASCII 13 is CR (Carriage Return), the first half of the Windows CR LF line ending — hex 0x0D, octal 015, binary 00001101.

ASCII 14 is SO (Shift Out) — hex 0x0E, octal 016, binary 00001110.

ASCII 15 is SI (Shift In) — hex 0x0F, octal 017, binary 00001111.

ASCII 16 is DLE (Data Link Escape) — hex 0x10, octal 020, binary 00010000.

ASCII 17 is DC1 (Device Control 1 (XON)) — hex 0x11, octal 021, binary 00010001.

ASCII 18 is DC2 (Device Control 2) — hex 0x12, octal 022, binary 00010010.

ASCII 19 is DC3 (Device Control 3 (XOFF)) — hex 0x13, octal 023, binary 00010011.

ASCII 20 is DC4 (Device Control 4) — hex 0x14, octal 024, binary 00010100.

ASCII 21 is NAK (Negative Acknowledge) — hex 0x15, octal 025, binary 00010101.

ASCII 22 is SYN (Synchronous Idle) — hex 0x16, octal 026, binary 00010110.

ASCII 23 is ETB (End of Transmission Block) — hex 0x17, octal 027, binary 00010111.

ASCII 24 is CAN (Cancel) — hex 0x18, octal 030, binary 00011000.

ASCII 25 is EM (End of Medium) — hex 0x19, octal 031, binary 00011001.

ASCII 26 is SUB (Substitute), the byte Ctrl+Z produces — hex 0x1A, octal 032, binary 00011010.

ASCII 27 is ESC (Escape), the byte that starts terminal escape sequences — hex 0x1B, octal 033, binary 00011011.

ASCII 28 is FS (File Separator) — hex 0x1C, octal 034, binary 00011100.

ASCII 29 is GS (Group Separator) — hex 0x1D, octal 035, binary 00011101.

ASCII 30 is RS (Record Separator) — hex 0x1E, octal 036, binary 00011110.

ASCII 31 is US (Unit Separator) — hex 0x1F, octal 037, binary 00011111.

ASCII 32 is the space character — hex 0x20, octal 040, binary 00100000.

ASCII 33 is the exclamation mark, "!" — hex 0x21, octal 041, binary 00100001.

ASCII 34 is the quotation mark (double quote), """ — hex 0x22, octal 042, binary 00100010.

ASCII 35 is the number sign (hash), "#" — hex 0x23, octal 043, binary 00100011.

ASCII 36 is the dollar sign, "$" — hex 0x24, octal 044, binary 00100100.

ASCII 37 is the percent sign, "%" — hex 0x25, octal 045, binary 00100101.

ASCII 38 is the ampersand, "&" — hex 0x26, octal 046, binary 00100110.

ASCII 39 is the apostrophe (single quote), "'" — hex 0x27, octal 047, binary 00100111.

ASCII 40 is the left parenthesis, "(" — hex 0x28, octal 050, binary 00101000.

ASCII 41 is the right parenthesis, ")" — hex 0x29, octal 051, binary 00101001.

ASCII 42 is the asterisk, "*" — hex 0x2A, octal 052, binary 00101010.

ASCII 43 is the plus sign, "+" — hex 0x2B, octal 053, binary 00101011.

ASCII 44 is the comma, "," — hex 0x2C, octal 054, binary 00101100.

ASCII 45 is the hyphen-minus, "-" — hex 0x2D, octal 055, binary 00101101.

ASCII 46 is the full stop (period), "." — hex 0x2E, octal 056, binary 00101110.

ASCII 47 is the solidus (slash), "/" — hex 0x2F, octal 057, binary 00101111.

ASCII 48 is the digit "0" — hex 0x30, octal 060, binary 00110000.

ASCII 49 is the digit "1" — hex 0x31, octal 061, binary 00110001.

ASCII 50 is the digit "2" — hex 0x32, octal 062, binary 00110010.

ASCII 51 is the digit "3" — hex 0x33, octal 063, binary 00110011.

ASCII 52 is the digit "4" — hex 0x34, octal 064, binary 00110100.

ASCII 53 is the digit "5" — hex 0x35, octal 065, binary 00110101.

ASCII 54 is the digit "6" — hex 0x36, octal 066, binary 00110110.

ASCII 55 is the digit "7" — hex 0x37, octal 067, binary 00110111.

ASCII 56 is the digit "8" — hex 0x38, octal 070, binary 00111000.

ASCII 57 is the digit "9" — hex 0x39, octal 071, binary 00111001.

ASCII 58 is the colon, ":" — hex 0x3A, octal 072, binary 00111010.

ASCII 59 is the semicolon, ";" — hex 0x3B, octal 073, binary 00111011.

ASCII 60 is the less-than sign, "<" — hex 0x3C, octal 074, binary 00111100.

ASCII 61 is the equals sign, "=" — hex 0x3D, octal 075, binary 00111101.

ASCII 62 is the greater-than sign, ">" — hex 0x3E, octal 076, binary 00111110.

ASCII 63 is the question mark, "?" — hex 0x3F, octal 077, binary 00111111.

ASCII 64 is the commercial at (at sign), "@" — hex 0x40, octal 100, binary 01000000.

ASCII 65 is the uppercase letter "A" — hex 0x41, octal 101, binary 01000001.

ASCII 66 is the uppercase letter "B" — hex 0x42, octal 102, binary 01000010.

ASCII 67 is the uppercase letter "C" — hex 0x43, octal 103, binary 01000011.

ASCII 68 is the uppercase letter "D" — hex 0x44, octal 104, binary 01000100.

ASCII 69 is the uppercase letter "E" — hex 0x45, octal 105, binary 01000101.

ASCII 70 is the uppercase letter "F" — hex 0x46, octal 106, binary 01000110.

ASCII 71 is the uppercase letter "G" — hex 0x47, octal 107, binary 01000111.

ASCII 72 is the uppercase letter "H" — hex 0x48, octal 110, binary 01001000.

ASCII 73 is the uppercase letter "I" — hex 0x49, octal 111, binary 01001001.

ASCII 74 is the uppercase letter "J" — hex 0x4A, octal 112, binary 01001010.

ASCII 75 is the uppercase letter "K" — hex 0x4B, octal 113, binary 01001011.

ASCII 76 is the uppercase letter "L" — hex 0x4C, octal 114, binary 01001100.

ASCII 77 is the uppercase letter "M" — hex 0x4D, octal 115, binary 01001101.

ASCII 78 is the uppercase letter "N" — hex 0x4E, octal 116, binary 01001110.

ASCII 79 is the uppercase letter "O" — hex 0x4F, octal 117, binary 01001111.

ASCII 80 is the uppercase letter "P" — hex 0x50, octal 120, binary 01010000.

ASCII 81 is the uppercase letter "Q" — hex 0x51, octal 121, binary 01010001.

ASCII 82 is the uppercase letter "R" — hex 0x52, octal 122, binary 01010010.

ASCII 83 is the uppercase letter "S" — hex 0x53, octal 123, binary 01010011.

ASCII 84 is the uppercase letter "T" — hex 0x54, octal 124, binary 01010100.

ASCII 85 is the uppercase letter "U" — hex 0x55, octal 125, binary 01010101.

ASCII 86 is the uppercase letter "V" — hex 0x56, octal 126, binary 01010110.

ASCII 87 is the uppercase letter "W" — hex 0x57, octal 127, binary 01010111.

ASCII 88 is the uppercase letter "X" — hex 0x58, octal 130, binary 01011000.

ASCII 89 is the uppercase letter "Y" — hex 0x59, octal 131, binary 01011001.

ASCII 90 is the uppercase letter "Z" — hex 0x5A, octal 132, binary 01011010.

ASCII 91 is the left square bracket, "[" — hex 0x5B, octal 133, binary 01011011.