%

• %{json}: Available --write-out variables​

  .

• .netrc: Command line leakage, .netrc​

  /

• /etc/hosts: Host name or address, Edit the hosts file​

  <

• <curl/curl.h>: include/curl, Include files, curl --libcurl, Header files, Get a simple HTML page, Get a HTML page in memory, Submit a login form over HTTP​

  A

• --alt-svc: Enable​

• --anyauth: HTTP authentication​

• apt: Ubuntu and Debian​

• Arch Linux: Arch Linux​

  B

• -b: Cookie engine, curl HTTP cheat sheet, Web logins and sessions​

• --basic: HTTP authentication​

• BoringSSL: Select TLS backend, Build to use a TLS library, Build curl with boringssl​

  C

• -c: Writing cookies to file, curl HTTP cheat sheet, Web logins and sessions​

• c-ares: c-ares, Line 4: Features, Name resolve tricks with c-ares, Name resolver backends​

• C89: Comments, Building and installing​

• CA: Verbose mode, MITM-proxies, Available exit codes, Verifying server certificates, Verification​

• Chrome: SSLKEYLOGFILE, Copy as curl​

• clone: Clone the code, git, Web site source code, build boringssl​

• code of conduct: Code of conduct​

• --compressed: Compression, Gzipped transfers, curl HTTP cheat sheet​

• configure: root, Handling different build options, On Linux and Unix-like systems, configure, [set up the build tree to get detected by curl's configure](source/build/boringssl.md#set-up-the-build-tree-to-get-detected-by-curl's-configure)

• --connect-timeout: Connection timeout, Never spend more than this to connect​

• --connect-to: Provide a replacement name​

• connection cache: Persistent connections, Connection reuse, Multi handle​

• connection pool: Connection reuse, Connection reuse​

• Connection reuse: Connection reuse, Connection reuse​

• content-encoding: Compression, Transfer encoding​

• contribute: Code of conduct, Contributing​

• Contributing: docs, Contributing​

• Cookie engine: Cookie engine, Cookie engine​

• Cookies: docs, libpsl, Server differences, Change the Host: header, Not perfect, HTTP authentication, Cookies, Cookies, Simple by default, more on demand, Available information, Sharing between easy handles, Submit a login form over HTTP, HTTP authentication, Cookies with libcurl​

• copyright: License, Copyright​

• curl-announce: curl-announce, Vulnerability handling​

• curl-library: curl-users, Make a patch for the mailing list, Vulnerability handling​

• curl-users: curl-users, Vulnerability handling​

• CURLE_ABORTED_BY_CALLBACK: Progress callback​

• CURLINFO_CERTINFO: Available information​

• CURLINFO_CONTENT_TYPE: Post transfer info​

• CURLINFO_EFFECTIVE_URL: Available information​

• CURLINFO_FILETIME: Available information​

• CURLINFO_TOTAL_TIME_T: Available information​

• CURLMOPT_SOCKETFUNCTION: socket_callback​

• CURLMOPT_TIMERFUNCTION: timer_callback​

• CURLOPT_CLOSEOCKETFUNCTION: Socket close callback​

• CURLOPT_COOKIE: Setting custom cookies​

• CURLOPT_COOKIEFILE: Submit a login form over HTTP, Enable cookie engine with reading​

• CURLOPT_COOKIEJAR: Enable cookie engine with writing​

• CURLOPT_COOKIELIST: Add a cookie to the cookie store​

• CURLOPT_CURLU: CURLOPT_CURLU​

• CURLOPT_CUSTOMREQUEST: Request method​

• CURLOPT_DEBUGDATA: Debug callback, Trace everything​

• CURLOPT_DEBUGFUNCTION: Debug callback, Trace everything​

• CURLOPT_DNS_CACHE_TIMEOUT: Caching​

• CURLOPT_DNS_INTERFACE: Name server options​

• CURLOPT_DNS_LOCAL_IP4: Name server options​

• CURLOPT_DNS_LOCAL_IP6: Name server options​

• CURLOPT_DNS_SERVERS: Name server options​

• CURLOPT_DNS_USE_GLOBAL_CACHE: No global DNS cache​

• CURLOPT_ERRORBUFFER: curl --libcurl, CURLcode return code​

• CURLOPT_FAILONERROR: [About HTTP response code "errors"](libcurl-http/responses.md#about-http-response-code-"errors")

• CURLOPT_HEADER: Write callback, Referrer, Download headers too​

• CURLOPT_HEADERDATA: Header callback, curl --libcurl, Download headers too​

• CURLOPT_HEADERFUNCTION: Header callback, curl --libcurl​

• CURLOPT_HTTPGET: Submit a login form over HTTP, libcurl HTTP download​

• CURLOPT_HTTPHEADER: Add a header​

• CURLOPT_IPRESOLVE: Name resolving​

• CURLOPT_MAXFILE_LARGE: Setting numerical options​

• CURLOPT_MAXREDIRS: curl --libcurl​

• CURLOPT_MIMEPOST: HTTP multipart formposts​

• CURLOPT_NOBODY: Request method​

• CURLOPT_NOPROGRESS: Progress callback, curl --libcurl​

• CURLOPT_OPENSOCKETDATA: Provide a file descriptor​

• CURLOPT_OPENSOCKETFUNCTION: Provide a file descriptor​

• CURLOPT_POST: HTTP POST​

• CURLOPT_POSTFIELDS: Submit a login form over HTTP, Request method, HTTP POST​

• CURLOPT_POSTFIELDSIZE: HTTP POST​

• CURLOPT_POSTREDIR: Decide what method to use in redirects​

• CURLOPT_PROGRESSFUNCTION: Progress callback​

• CURLOPT_PROXY: Proxy types​

• CURLOPT_PROXYPORT: Proxy types​

• CURLOPT_PROXYTYPE: Proxy types​

• CURLOPT_READDATA: Read callback, curl --libcurl​

• CURLOPT_READFUNCTION: Read callback, curl --libcurl, HTTP POST​

• CURLOPT_RESOLVE: Custom addresses for hosts​

• CURLOPT_SEEKDATA: curl --libcurl​

• CURLOPT_SEEKFUNCTION: curl --libcurl​

• CURLOPT_SOCKOPTDATA: sockopt callback​

• CURLOPT_SOCKOPTFUNCTION: sockopt callback​

• CURLOPT_SSH_KNOWNHOSTS: curl --libcurl​

• CURLOPT_SSLVERSION: Protocol version​

• CURLOPT_SSL_VERIFYHOST: Verification​

• CURLOPT_SSL_VERIFYPEER: HTTPS proxy, Verification​

• CURLOPT_STDERR: curl --libcurl, Verbose operations​

• CURLOPT_TCP_KEEPALIVE: curl --libcurl​

• CURLOPT_TIMEOUT: Setting numerical options​

• CURLOPT_TLSAUTH_USERNAME: TLS auth​

• CURLOPT_UPLOAD: Request method, HTTP PUT​

• CURLOPT_URL: Easy handle, curl --libcurl, Set handle options, Get a simple HTML page, Get a HTML page in memory, Submit a login form over HTTP, Request method, libcurl HTTP download, HTTP PUT​

• CURLOPT_USERAGENT: curl --libcurl, Get a HTML page in memory​

• CURLOPT_VERBOSE: Verbose operations, Download headers too​

• CURLOPT_WRITEDATA: Write callback, curl --libcurl, Get a HTML page in memory​

• CURLOPT_WRITEFUNCTION: Write callback, curl --libcurl, Get a HTML page in memory​

• CURLOPT_XFERINFODATA: Progress callback​

• CURLOPT_XFERINFOFUNCTION: Progress callback​

• CURLUPART_FRAGMENT: Get individual URL parts​

• CURLUPART_HOST: Get individual URL parts​

• CURLUPART_PASSWORD: Get individual URL parts​

• CURLUPART_PATH: Get individual URL parts​

• CURLUPART_PORT: Get individual URL parts​

• CURLUPART_QUERY: Get individual URL parts​

• CURLUPART_USER: Get individual URL parts​

• curl_easy_cleanup: easy handle, curl --libcurl, Get a simple HTML page, Get a HTML page in memory, Submit a login form over HTTP, Enable cookie engine with writing​

• curl_easy_getinfo: docs/libcurl/opts, Post transfer info, HTTP responses, Get all cookies from the cookie store​

• curl_easy_init: Easy handle, curl --libcurl, Get a simple HTML page, Get a HTML page in memory, Submit a login form over HTTP, libcurl HTTP download​

• curl_easy_perform: Driving with the easy interface, Easy API pool, Caching, curl --libcurl, Get a simple HTML page, Get a HTML page in memory, Submit a login form over HTTP, Add a header, libcurl HTTP download, Everything is multi​

• curl_easy_reset: Reuse!​

• curl_easy_setopt: docs/libcurl/opts, Easy handle, Write callback, Read callback, Progress callback, Header callback, Debug callback, sockopt callback, Provide a file descriptor, Name resolving, Sharing between easy handles, curl --libcurl, Set handle options, libcurl TLS options, CURLcode return code, Verbose operations, Get a simple HTML page, Get a HTML page in memory, Submit a login form over HTTP, Request method, HTTP ranges, User name and password, Enable cookie engine with reading, libcurl HTTP download, HTTP POST​

• curl_global_cleanup: Global initialization, Get a HTML page in memory​

• curl_global_init: Global initialization, Get a HTML page in memory​

• CURL_IPRESOLVE_V6: Name resolving​

• CURL_MAX_WRITE_SIZE: Write callback​

• curl_mime_addpart: HTTP multipart formposts​

• curl_mime_filedata: HTTP multipart formposts​

• curl_mime_init: HTTP multipart formposts​

• curl_mime_name: HTTP multipart formposts​

• curl_multi_add_handle: Driving with the multi interface, Many easy handles​

• curl_multi_cleanup: Multi API​

• curl_multi_fdset: Driving with the multi interface​

• curl_multi_info_read: When is a single transfer done?, When is it done?, Multi API​

• curl_multi_init: Driving with the multi interface​

• curl_multi_remove_handle: Driving with the multi interface, Many easy handles, Multi API​

• curl_multi_setopt: docs/libcurl/opts, Driving with the multi interface, socket_callback​

• curl_multi_socket_action: socket_callback​

• curl_multi_timeout: Driving with the multi interface​

• curl_multi_wait: Driving with the multi interface​

• curl_off_t: Progress callback, Available information, Setting numerical options, HTTP PUT​

• CURL_SOCKET_TIMEOUT: timer_callback​

• CURL_SSL_BACKEND: Line 1: TLS versions, Multiple TLS backends​

• curl_url: Create, cleanup, duplicate​

• curl_url_cleanup: Create, cleanup, duplicate​

• curl_url_dup: Create, cleanup, duplicate​

• curl_url_get: Get a URL​

• curl_url_set: Parse a URL​

• curl_version_info: Which libcurl version runs​

  D

• -d: Arguments to options, Separate options per URL, POST, MQTT, HTTP methods, HTTP POST, -d vs -F, PUT, curl HTTP cheat sheet, Web logins and sessions​

• --data: Arguments to options, Separate options per URL, POST, HTTP POST​

• --data-binary: Not perfect, POSTing binary​

• --data-urlencode: URL encoding​

• debian: Ubuntu and Debian, lib/vtls, Version​

• Debug callback: Debug callback, Verbose operations​

• development: Project communication, curl-users, Reporting bugs, The development team, Future, Ubuntu and Debian, Development, Who decides what goes in?, From Safari, Figure out what a browser sends, Which libcurl version runs, Verification​

  E

• environment variables: Default config file, Proxy environment variables, Proxy environment variables​

• etiquette: Mailing list etiquette​

• event-driven: [Driving with the "multi_socket" interface](libcurl/drive/multi-socket.md#driving-with-the-"multi_socket"-interface), Everything is multi​

  F

• -F: multipart formpost, Not perfect, HTTP methods, Sending such a form with curl, -d vs -F, curl HTTP cheat sheet​

• --fail: Available exit codes, HTTP response codes​

• --fail-with-body: HTTP response codes​

• Firefox: lib/vtls, Discover your proxy, SSLKEYLOGFILE, Copy as curl, User-agent​

• Fragment: Fragment, Anchors or fragments​

• --ftp-method: multicwd​

• --ftp-pasv: Passive connections​

• --ftp-port: Available exit codes, Active connections​

• --ftp-skip-pasv-ip: Passive connections​

• future: Project communication, Future, docs, [email protected], What other protocols are there?, ["Not used"](usingcurl/returns.md#"not-used"), Cookies, Multiplexing, When QUIC is denied, API compatibility​

  G

• --get: Convert that to a GET​

• git: Daily snapshots, Clone the code, root, git, Web site source code, git vs tarballs, build boringssl​

• Globbing: URL globbing​

• GnuTLS: Build to use a TLS library, OCSP stapling, Proxy types​

• GOPHER: How it started, What protocols does curl support?, GOPHER, Supported protocols, Version​

• GOPHERS: What protocols does curl support?, GOPHERS, Supported protocols​

  H

• --header: Server differences, Proxy headers, Customize headers​

• Header callback: Header callback, HTTP responses​

• Host:: Verbose mode, --trace and --trace-ascii, Change the Host: header, HTTP protocol basics, The HTTP this generates, Customize headers, Customize HTTP request headers​

• HTTP ranges: HTTP ranges, HTTP ranges​

• HTTP redirects: Short options, Available exit codes, HTTP redirects, Submit a login form over HTTP​

• HTTP/1.1: HTTP, Verbose mode, --trace and --trace-ascii, HTTP protocol basics, HTTP versions, The HTTP this generates, GET or POST?, Request method, HTTP/2, Customize HTTP request headers, HTTP versions​

• HTTP/2: docs, nghttp2, HTTP/2 and HTTP/3, Line 4: Features, Available exit codes, HTTP versions, GET or POST?, HTTP/2, HTTP/3, DNS over HTTPS, HTTP versions, Expect: headers​

• HTTP/3: Select HTTP/3 backend, HTTP/2 and HTTP/3, Line 4: Features, HTTP/3, HTTP/3, Which libcurl version runs, HTTP versions, Expect: headers​

• HTTP/3 backend: Select HTTP/3 backend​

• --http1.1: HTTP versions​

• --http2: HTTP versions, HTTP/2​

• --http2-prior-knowledge: HTTP versions, HTTP/2​

• --http3: HTTP versions, Enable​

• HttpGet: How it started​

  I

• IDN: libidn2, Version​

• Indentation: Indentation​

• IPv4: Host name or address, Available --write-out variables, Name resolving​

• IPv6: Host name or address, URL globbing, Available --write-out variables, Version, Name resolving​

• IRC: How it started, Project communication​

  J

• JavaScript: Client differences, PAC, JavaScript and forms, JavaScript redirects, Figure out what the browser does​

• json: Arguments with spaces, Available --write-out variables, Content-Type, POST outside of HTML​

  K

• -K: Command lines, quotes and aliases, Config file​

• keep-alive: Keep connections alive​

• --keepalive-time: Keep alive, Keep connections alive​

  L

• -L: Short options, Available --write-out variables, Tell curl to follow redirects, Request method, Cookie engine, curl HTTP cheat sheet, Redirects​

• --libcurl: curl --libcurl​

• libcurl version: The latest version?, Line 1: curl, Available exit codes, Which libcurl version​

• libidn2: libidn2​

• libpsl: libpsl​

• libressl: Select TLS backend, Build to use a TLS library​

• librtmp: librtmp​

• libssh2: libssh2​

• license: Finding users, License, root​

• --limit-rate: Rate limiting​

• --location: Long options, Separate options per URL, Config file, Tell curl to follow redirects​

  M

• --max-filesize: Maximum filesize​

• --max-time: Retrying failed attempts, Maximum time allowed to spend​

• MesaLink: Build to use a TLS library​

• MIT: License​

• MITM-proxies: MITM-proxies​

• MQTT: What protocols does curl support?, MQTT, Supported protocols, Line 3: Protocols, MQTT​

• mTLS: Client certificates​

• multi-threading: libcurl multi-threading​

  N

• name resolving: Handling different build options, Host name resolving, Available --write-out variables, Name resolve tricks with c-ares, SOCKS types, Connection reuse, Name resolving, Proxy types, Available information​

• --negotiate: Network leakage, HTTP authentication​

• --netrc-file: Enable netrc​

• --netrc-optional: Enable netrc​

• nghttp2: nghttp2, Which libcurl version runs​

• nix: nix​

• --no-eprt: Active connections​

• --no-epsv: Passive connections​

• NSS: Build to use a TLS library, OCSP stapling, Proxy types​

• --ntlm: Network leakage, HTTP authentication​

  O

• -O: Many options and URLs, Numerical ranges, Download to a file named by the URL, curl HTTP cheat sheet​

• openldap: openldap​

• OpenSSL: lib/vtls, Select TLS backend, Build to use a TLS library, OCSP stapling, Proxy types, Available information​

  P

• PAC: PAC, Which proxy?​

• --parallel: Do the transfers in parallel​

• --parallel-max: Do the transfers in parallel​

• Percent-encoding: URL encoding​

• pop3: What protocols does curl support?, POP3, Without scheme, Supported protocols, Verbose mode, Version, Available exit codes, Reading email, Secure mail transfer, Enable TLS, STARTTLS​

• port number: [Connects to "port numbers"](protocols/network.md#connects-to-"port-numbers"), Port number, Available --write-out variables, Provide a replacement name, HTTP, Available exit codes, The URL converted to a request, Enable, Connection reuse, Custom addresses for hosts, Proxies, Post transfer info​

• --post301: Decide what method to use in redirects​

• --post302: Decide what method to use in redirects​

• --post303: Decide what method to use in redirects​

• Progress callback: timer_callback, Progress callback​

• pronunciation: Pronunciation​

• --proxy: HTTP, HTTP authentication​

• proxy: How it started, Available --write-out variables, Line 4: Features, [Intermediaries' fiddlings](usingcurl/downloads.md#intermediaries'-fiddlings), Proxies, Available exit codes, CONNECT response codes, HTTP authentication, Proxies, Available information, Verification, HTTP proxy​

• --proxy-user: Proxy authentication, HTTP authentication​

• --proxy1.0: HTTP proxy tunneling​

• --proxytunnel: HTTP proxy tunneling​

  R

• ranges: Numerical ranges, Resuming and ranges, HTTP ranges, Provide a file descriptor, HTTP response code, HTTP ranges​

• Read callback: Read callback, HTTP POST​

• redhat: Redhat and Centos, lib/vtls​

• redirects: Long options, Separate options per URL, Config file, Available --write-out variables, Download to a file named by the URL, Provide a custom IP address for a name, Available exit codes, HTTP redirects, Request method, Redirects, Custom addresses for hosts, Available information, Submit a login form over HTTP, Automatic referrer​

• RELEASE-NOTES: scripts​

• releases: [1. The cURL project](how-to-read.md#1.-the-curl-project), curl-announce, Releases, scripts, Verbose mode, Which libcurl version​

• --remote-name-all: [Use the URL's file name part for all URLs](usingcurl/downloads.md#use-the-url's-file-name-part-for-all-urls)

• repository: Releases, Arch Linux, Source code on GitHub, Hosting and download, root, What to add, Web site source code, git vs tarballs​

• --resolve: Provide a custom IP address for a name​

• RFC 1436: GOPHER​

• RFC 1738: FILE, multicwd​

• RFC 1939: POP3​

• RFC 1945: HTTP redirects​

• RFC 2229: DICT​

• RFC 2246: SSL and TLS versions​

• RFC 2326: RTSP​

• RFC 2595: IMAP​

• RFC 2818: HTTPS​

• RFC 3207: SMTP​

• RFC 3501: IMAP​

• RFC 3986: URLs​

• RFC 4217: FTPS​

• RFC 4511: LDAP​

• RFC 5321: SMTP​

• RFC 7230: HTTP​

• RFC 7540: HTTP​

• RFC 7838: Alternative Services​

• RFC 8314: IMAPS​

• RFC 8446: SSL and TLS versions​

• RFC 854: TELNET​

• RFC 959: FTP, FTP​

• RTMP: librtmp, What protocols does curl support?, RTMP, Supported protocols, Version​

• RTSP: What protocols does curl support?, RTSP, Supported protocols, Version, RTSP interleave callback, Available information​

  S

• Safari: Copy as curl​

• Schannel: Build to use a TLS library, CA store on windows​

• Scheme: librtmp, [Connects to "port numbers"](protocols/network.md#connects-to-"port-numbers"), FILE, Scheme, Available --write-out variables, Proxy type, Available exit codes, TLS for emails, Proxy types, Available information, Which libcurl version, Get a HTML page in memory, HTTPS, HTTP authentication, Bindings, [Different protocols "hooked in"](internals.md#different-protocols-"hooked-in")

• SCP: libssh2, What protocols does curl support?, SCP, Supported protocols, Version, Protocols allowing upload, Available exit codes, SCP and SFTP​

• security: curl-announce, Security, Trust, docs, Reporting vulnerabilities, TLS, How much do protocols change?, FTPS, http_proxy in lower case only, TLS, How to HTTP with curl, URL API, Protocol version, HTTPS​

• SFTP: libssh2, What protocols does curl support?, SFTP, Supported protocols, --trace and --trace-ascii, Version, Protocols allowing upload, Available exit codes, SCP and SFTP​

• --show-error: Silence​

• --silent: The progress meter, Silence, Error message​

• SMTP: What protocols does curl support?, SMTP, Without scheme, Supported protocols, Verbose mode, Version, Protocols allowing upload, Available exit codes, Sending email, Enable TLS, STARTTLS​

• SMTPS: Build to use a TLS library, What protocols does curl support?, SMTPS, Supported protocols, Version, Protocols allowing upload, Enable TLS​

• snapshots: Daily snapshots, root​

• SNI: Change the Host: header​

• --socks4: SOCKS types​

• --socks4a: SOCKS types​

• --socks5: SOCKS types​

• --socks5-hostname: SOCKS types​

• --speed-limit: Transfer speeds slower than this means exit​

• --speed-time: Transfer speeds slower than this means exit​

• SSH: Select SSH backend, SCP, Available exit codes, SCP and SFTP, SSH key callback, Trace everything​

• SSH backend: Select SSH backend​

• SSL context callback: SSL context callback​

• SSLKEYLOGFILE: SSLKEYLOGFILE​

• STARTTLS: IMAP, TLS for emails, STARTTLS​

  T

• -T: PUT, Uploading with FTP, HTTP methods, PUT, curl HTTP cheat sheet​

• TELNET: What protocols does curl support?, TELNET, Supported protocols, Version, Available exit codes, TELNET​

• testing: What does curl do?, Reporting bugs, Handling different build options, Contributing, [About HTTP response code "errors"](libcurl-http/responses.md#about-http-response-code-"errors")

• TLS: Ubuntu and Debian, lib/vtls, Handling different build options, Select TLS backend, TLS libraries, Build to use a TLS library, TLS, How much do protocols change?, GOPHERS, Connection reuse, Verbose mode, Line 1: curl, Change the Host: header, MITM-proxies, Available exit codes, SCP and SFTP, TLS for emails, Caveats, TLS, SSLKEYLOGFILE, How to HTTP with curl, The URL converted to a request, HTTPS, Figure out what a browser sends, HTTPS only, Proxy types, Available information, libcurl TLS options, Trace everything, HTTPS​

• TLS backend: Ubuntu and Debian, lib/vtls, Select TLS backend, Line 1: curl, Certificate pinning​

• TODO: Suggestions​

• --tr-encoding: Compression, Transfer encoding​

• --trace: --trace and --trace-ascii​

• --trace-ascii: --trace and --trace-ascii, Server differences, curl HTTP cheat sheet​

• --trace-time: --trace-time​

• transfer-encoding: Pass on transfer encoding, Chunked encoded POSTs​

  U

• -u: Passwords and snooping, Authentication, URLs, IMAP, HTTP authentication, curl HTTP cheat sheet​

• -U: Proxy authentication​

• Ubuntu: Ubuntu and Debian​

• URL Globbing: URL globbing​

  V

• --verbose: Long options, Verbose mode, --trace-time​

• --version: Version, Multiple TLS backends​

• Vulnerability: Vulnerability handling​

  W

• Wireshark: --trace and --trace-ascii, Available exit codes, SSLKEYLOGFILE, Figure out what a browser sends​

• wolfSSL: Build to use a TLS library​

• Write callback: Write callback, Get a HTML page in memory, HTTP responses​

• --write-out: --write-out, HTTP response codes​

  X

• -x: HTTP, curl HTTP cheat sheet, Proxy environment variables​

• -X: Request method, PUT, curl HTTP cheat sheet​

  Y

• yum: Redhat and Centos​

  Z

• -Z: Do the transfers in parallel​

• zlib: zlib​