Index

A

• --alt-svc:Enable
• --anyauth:Authentication
• --append:trurl example command lines,FTP and SFTP uploads,Uploading with FTP
• apt:Ubuntu and Debian
• Arch Linux:Arch Linux
• AWS sigv4:AWS sigv4
• --aws-sigv4:AWS sigv4

B

• -b:Cookie engine,Reading cookies from file,Writing cookies to file,New cookie session,Web logins and sessions
• --basic:Authentication
• BearSSL:lib/vtls,TLS libraries,<features>
• bindings:Confusions and mix-ups,libcurl, the library,In website backends,docs
• BoringSSL:TLS libraries,BoringSSL,Restrictions,HTTP/3 backends
• brotli:HTTP Compression,Version,Which libcurl version runs,About content encodings,Conditional lines

C

• -c:Writing cookies to file,Web logins and sessions
• c-ares:c-ares,Line 4: Features,Name resolve tricks with c-ares,Name resolver backends,CURLRES_ARES,<features>
• C89:Comments
• CA:Available exit codes,MITM proxy,Verifying server certificates,OCSP stapling,Caches,CA store caching,Verification,All options,Available information,CA store cache
• CA cert cache:CA cert cache
• --ca-native:Native CA stores
• Chrome:Copy as curl,SSLKEYLOGFILE
• clone:Building libcurl on MSYS2,git,Website,build boringssl
• code of conduct:Trust,Code of Conduct
• --compressed:Gzipped transfers,Compression,The curl interface
• --compressed-ssh:For SFTP/SCP
• configure:root,Handling build options,Platform dependent code,Autotools,rpath,configure,set up the build tree to get detected by curl's configure,Ifdefs,Memory debugging,Debug builds
• --connect-timeout:Connection timeout,Never spend more than this to connect
• --connect-to:Provide a replacement name
• connection cache:Connection reuse,Available --write-out variables,Connection cache,All options,Connection reuse,Multi handle,connection cache,connectdata
• connection pool:Connection reuse,Connection cache,pool size,Connection reuse,connection cache
• Connection reuse:Connection reuse,Connection cache,threads,Connection reuse
• content-encoding:Transfer encoding,Compression,About content encodings
• contribute:Code of Conduct,Contributing,Everything curl
• Contributing:docs,Contributing
• Cookie engine:Cookie engine,Writing cookies to file,Cookie engine
• Cookies:docs,libpsl,Line 4: Features,Not perfect,Server differences,Change the Host: header,Authentication,Cookie engine,Reading cookies from file,Writing cookies to file,New cookie session,Cookie file format,Cookies,All options,Available information,Authentication,Cookies,Sharing between easy handles,Submit a login form over HTTP,Cookies,Curl_share,<features>
• 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
• <curl/curl.h>:include/curl,Header files,--libcurl,Stop slow transfers,Rate limit,Progress meter,Include files,Get a simple HTTP page,Get a response into memory,Submit a login form over HTTP,Get an FTP directory listing,Non-blocking HTTP form-post
• CURLE_ABORTED_BY_CALLBACK:Progress information
• CURLHSTS_ENABLE:Enable HSTS for a handle
• CURLHSTS_READONLYFILE:Enable HSTS for a handle
• CURLINFO_CERTINFO:Available information
• CURLINFO_CONN_ID:Transfer and connection identifiers,Available information
• CURLINFO_CONTENT_TYPE:Post transfer info
• CURLINFO_EFFECTIVE_URL:Available information
• CURLINFO_FILETIME:Available information
• CURLINFO_TOTAL_TIME_T:Available information
• CURLINFO_XFER_ID:Transfer and connection identifiers,Available information
• CURLMOPT_PIPELINING:Multiplexing
• CURLMOPT_SOCKETFUNCTION:socket_callback
• CURLMOPT_TIMERFUNCTION:timer_callback,Exposes just a single timeout to apps
• CURLOPT_ALTSVC:All options,Enable
• CURLOPT_ALTSVC_CTRL:All options,Enable
• CURLOPT_CA_CACHE_TIMEOUT:CA cert cache,All options
• CURLOPT_CLOSESOCKETFUNCTION:All options,Socket close callback
• CURLOPT_CONNECTTIMEOUT:All options,easy API
• CURLOPT_COOKIE:All options,Setting custom cookies
• CURLOPT_COOKIEFILE:All options,Enable cookie engine with reading,Submit a login form over HTTP
• CURLOPT_COOKIEJAR:All options,Enable cookie engine with writing
• CURLOPT_COOKIELIST:All options,Add a cookie to the cookie store
• CURLOPT_CURLU:All options,CURLOPT_CURLU
• CURLOPT_CUSTOMREQUEST:All options,Request method
• CURLOPT_DEBUGDATA:Trace everything,All options,Debug
• CURLOPT_DEBUGFUNCTION:Trace everything,All options,Debug
• CURLOPT_DNS_CACHE_TIMEOUT:DNS cache,All options,Caching
• CURLOPT_DNS_INTERFACE:All options,Name server options
• CURLOPT_DNS_LOCAL_IP4:All options,Name server options
• CURLOPT_DNS_LOCAL_IP6:All options,Name server options
• CURLOPT_DNS_SERVERS:All options,Name server options
• CURLOPT_DNS_USE_GLOBAL_CACHE:All options,No global DNS cache
• CURLOPT_ERRORBUFFER:--libcurl,CURLcode return codes,All options
• CURLOPT_FAILONERROR:All options,About HTTP response code "errors"
• CURLOPT_HEADER:All options,Write data,Referrer,Download headers too
• CURLOPT_HEADERDATA:--libcurl,All options,Header data,Download headers too
• CURLOPT_HEADERFUNCTION:--libcurl,All options,Header data
• CURLOPT_HSTS:All options,Set a HSTS cache file
• CURLOPT_HSTS_CTRL:All options,Enable HSTS for a handle
• CURLOPT_HTTPGET:All options,Download,Submit a login form over HTTP
• CURLOPT_HTTPHEADER:All options,Add a header,HTTP PUT,Non-blocking HTTP form-post
• CURLOPT_HTTPPOST:All options
• CURLOPT_IPRESOLVE:All options,How libcurl connects,Name resolving
• CURLOPT_LOCALPORT:All options,Local port number
• CURLOPT_LOCALPORTRANGE:All options,Local port number
• CURLOPT_LOW_SPEED_LIMIT:All options,easy API,Stop slow transfers
• CURLOPT_LOW_SPEED_TIME:All options,easy API,Stop slow transfers
• CURLOPT_MAXFILESIZE_LARGE:Set numerical options,All options
• CURLOPT_MAXREDIRS:--libcurl,All options
• CURLOPT_MIMEPOST:All options,HTTP multipart formposts,Non-blocking HTTP form-post
• CURLOPT_NOBODY:All options,Request method
• CURLOPT_NOPROGRESS:--libcurl,All options,Progress information,Progress meter
• CURLOPT_OPENSOCKETDATA:All options,Provide a file descriptor
• CURLOPT_OPENSOCKETFUNCTION:All options,Provide a file descriptor
• CURLOPT_PIPEWAIT:All options,Multiplexing
• CURLOPT_POST:All options,HTTP POST
• CURLOPT_POSTFIELDS:Set string options,All options,Request method,HTTP POST,Submit a login form over HTTP
• CURLOPT_POSTFIELDSIZE:CURLOPT_POSTFIELDS,All options,HTTP POST
• CURLOPT_POSTREDIR:Decide what method to use in redirects,All options
• CURLOPT_PROGRESSFUNCTION:All options,Progress information
• CURLOPT_PROXY:All options,Proxy types
• CURLOPT_PROXYPORT:All options,Proxy types
• CURLOPT_PROXYTYPE:All options,Proxy types
• CURLOPT_READDATA:--libcurl,All options,Read data
• CURLOPT_READFUNCTION:--libcurl,All options,Read data,HTTP POST
• CURLOPT_RESOLVE:All options,Custom addresses for hosts
• CURLOPT_SEEKDATA:--libcurl,All options,Seek and ioctl
• CURLOPT_SEEKFUNCTION:--libcurl,All options,Seek and ioctl
• CURLOPT_SOCKOPTDATA:All options,sockopt
• CURLOPT_SOCKOPTFUNCTION:All options,sockopt
• CURLOPT_SSH_KNOWNHOSTS:--libcurl,All options,SSH key
• CURLOPT_SSLVERSION:Protocol version,All options
• CURLOPT_SSL_VERIFYHOST:Verification,All options
• CURLOPT_SSL_VERIFYPEER:Verification,All options,HTTPS proxy
• CURLOPT_STDERR:--libcurl,Verbose operations,All options
• CURLOPT_TCP_KEEPALIVE:--libcurl,All options,Enable keep alive
• CURLOPT_TCP_KEEPCNT:Probe count
• CURLOPT_TCP_KEEPIDLE:All options,Idle time
• CURLOPT_TCP_KEEPINTVL:All options,Probe interval
• CURLOPT_TIMEOUT:Set numerical options,All options,easy API
• CURLOPT_TLSAUTH_USERNAME:TLS auth,All options
• CURLOPT_UPLOAD:All options,Request method,HTTP PUT
• CURLOPT_URL:--libcurl,Strings are C strings, not C++ string objects,Easy handle,Set string options,All options,Example,Stop slow transfers,Rate limit,Progress meter,Request method,Bearer,Download,HTTP PUT,CURLOPT_CURLU,Get a simple HTTP page,Get a response into memory,Submit a login form over HTTP,Get an FTP directory listing,Non-blocking HTTP form-post
• CURLOPT_USERAGENT:--libcurl,All options,Get a response into memory
• CURLOPT_VERBOSE:Verbose operations,All options,Find a specific option by name,When connections are not reused as you want,Download headers too,Non-blocking HTTP form-post
• CURLOPT_WRITEDATA:--libcurl,Callback considerations,All options,Write data,Get a response into memory
• CURLOPT_WRITEFUNCTION:--libcurl,Callback considerations,All options,Write data,Get a response into memory
• CURLOPT_XFERINFODATA:All options,Progress information
• CURLOPT_XFERINFOFUNCTION:All options,Progress information
• CURLUPART_FRAGMENT:Get URL parts,Set URL parts
• CURLUPART_HOST:CURLU_PUNYCODE,Get URL parts,Set URL parts
• CURLUPART_PASSWORD:Get URL parts,Set URL parts
• CURLUPART_PATH:Get URL parts,Set URL parts
• CURLUPART_PORT:Get URL parts,Set URL parts
• CURLUPART_QUERY:Get URL parts,Set URL parts,Append to the query
• CURLUPART_USER:Get URL parts,Set URL parts
• curl_easy_cleanup:--libcurl,Stop slow transfers,Rate limit,Progress meter,easy handle,Bearer,Enable cookie engine with writing,Header struct,Get a simple HTTP page,Get a response into memory,Submit a login form over HTTP,Get an FTP directory listing,Non-blocking HTTP form-post
• curl_easy_getinfo:docs/libcurl/opts,Transfer and connection identifiers,Post transfer info,Response meta-data,Get all cookies from the cookie store
• curl_easy_init:--libcurl,Easy handle,Example,Stop slow transfers,Rate limit,Progress meter,Bearer,Download,CURLOPT_CURLU,Get a simple HTTP page,Get a response into memory,Submit a login form over HTTP,Get an FTP directory listing,Non-blocking HTTP form-post
• curl_easy_option_by_id:Find a specific option by ID
• curl_easy_option_by_next:Iterate over all options
• curl_easy_perform:--libcurl,Drive with easy,Easy API pool,Example,Caching,easy API,Stop slow transfers,Rate limit,Progress meter,Add a header,Bearer,Download,Get a simple HTTP page,Get a response into memory,Submit a login form over HTTP,Get an FTP directory listing,Everything is multi
• curl_easy_reset:Reuse
• curl_easy_setopt:docs/libcurl/opts,--libcurl,CURLcode return codes,Verbose operations,Strings are C strings, not C++ string objects,Easy handle,Set numerical options,Set string options,TLS options,All options,Write data,Read data,Progress information,Header data,Debug,sockopt,Provide a file descriptor,Example,Name resolving,Stop slow transfers,Rate limit,Progress meter,Request method,Ranges,Username and password,Enable cookie engine with reading,Download,HTTP POST,Multiplexing,Enable HSTS for a handle,Enable,Sharing between easy handles,CURLOPT_CURLU,Get a simple HTTP page,Get a response into memory,Submit a login form over HTTP,Get an FTP directory listing,Non-blocking HTTP form-post,The libcurl interface
• curl_global_cleanup:Global initialization,Get a response into memory,Get an FTP directory listing
• curl_global_init:Global initialization,Get a response into memory,Get an FTP directory listing,Init calls
• curl_global_trace:Trace more
• CURL_IPRESOLVE_V6:Name resolving
• CURL_MAX_WRITE_SIZE:Write data
• curl_mime_addpart:HTTP multipart formposts,Non-blocking HTTP form-post
• curl_mime_filedata:HTTP multipart formposts,Non-blocking HTTP form-post
• curl_mime_init:HTTP multipart formposts,Non-blocking HTTP form-post
• curl_mime_name:HTTP multipart formposts,Non-blocking HTTP form-post
• curl_multi_add_handle:Drive with multi,Many easy handles,Non-blocking HTTP form-post,Curl_multi
• curl_multi_cleanup:Multi API,Non-blocking HTTP form-post
• curl_multi_fdset:Drive with multi,Curl_easy
• curl_multi_info_read:When is a single transfer done?,When is it done?,Multi API,Curl_multi
• curl_multi_init:Drive with multi,Non-blocking HTTP form-post
• curl_multi_remove_handle:Drive with multi,Many easy handles,multi API,Multi API
• curl_multi_setopt:docs/libcurl/opts,Drive with multi,socket_callback,Multiplexing
• curl_multi_socket_action:curl_multi_socket_action,socket_callback
• curl_multi_timeout:Drive with multi,Exposes just a single timeout to apps
• curl_multi_wait:Drive with multi
• curl_off_t:Transfer and connection identifiers,Set numerical options,Progress information,Seek and ioctl,Rate limit,Available information,Response meta-data,HTTP PUT,Meta,curl_ws_send()
• CURL_SOCKET_TIMEOUT:timer_callback
• CURL_SSL_BACKEND:Line 1: TLS versions,Multiple TLS backends
• curl_url:Include files,Create, cleanup, duplicate,Parse a URL,Redirect to URL,Update parts,CURLOPT_CURLU
• curl_url_cleanup:Create, cleanup, duplicate
• curl_url_dup:Create, cleanup, duplicate
• curl_url_get:CURLU_ALLOW_SPACE,Get a URL,Get URL parts
• curl_url_set:Include files,Parse a URL,Redirect to URL,Set URL parts,Append to the query,CURLOPT_CURLU
• curl_version_info:Which libcurl version runs,Support

D

• -d:Arguments to options,Separate options per URL,POST,MQTT,Method,Simple POST,Content-Type,Posting binary,Convert to GET,Expect 100-continue,Chunked encoded POSTs,Hidden form fields,-d vs -F,HTTP PUT,Web logins and sessions
• --data:Arguments to options,Separate options per URL,POST,Simple POST,JSON,URL encode data
• --data-binary:Not perfect,Simple POST,Posting binary,URL encode data
• --data-urlencode:Query,URL encode data,Convert to GET
• debian:Ubuntu and Debian,Version
• Debug callback:Verbose operations,All options,Debug
• development:Project communication,curl-users,Reporting bugs,Commercial support,Development,The development team,Future,Ubuntu and Debian,Get libcurl for macOS,Who decides what goes in?,From Safari,Figure out what a browser sends,Converting a web form,Which libcurl version runs,Verification,Debug builds
• DICT:What protocols does curl support?,DICT,Without scheme,Version,DICT,CURLU_GUESS_SCHEME

E

• Edge:Copy as curl,Ifdefs
• environment variables:Environment variables,Windows,Proxy environment variables,Proxy environment variables,<setenv>
• ephemeral port:Local port number
• ETag:Conditionals
• --etag-compare:Check by modification of content
• --etag-save:Check by modification of content
• /etc/hosts:Run a local clone,Host,Edit the hosts file
• etiquette:Mailing list etiquette
• event-driven:Drive with multi_socket,Everything is multi

F

• -F:Not perfect,multipart formpost,Method,Sending such a form with curl,-d vs -F
• --fail:Available exit codes,HTTP response codes
• --fail-with-body:HTTP response codes
• Firefox:Copy as curl,Discover your proxy,SSLKEYLOGFILE,User-agent
• Fragment:Query,Fragment,Available --write-out variables,Fragment,Write callback,Meta,curl_ws_send()
• --ftp-method:multicwd
• --ftp-pasv:Passive connections
• --ftp-port:Available exit codes,Active connections
• --ftp-skip-pasv-ip:Passive connections
• FTPS:What protocols does curl support?,FTPS,TLS libraries,Supported schemes,Network leakage,Version,Trace options,Protocols allowing upload,Enable TLS,FTPS,Variables
• future:Project communication,Future,What other protocols are there?,docs,curl-security@haxx.se,"Not used",More data,API compatibility,Trace more,Network data conversion,HSTS,age,Set a timeout

G

• --get:trurl example command lines,Convert to GET
• git:Daily snapshots,Backdoors and supply chain risks,Building libcurl on MSYS2,root,git,Website,build boringssl,Continuous Integration,Autobuilds
• Globbing:URL globbing,Globbing,Skip download if already done,Uploading with FTP
• GnuTLS:lib/vtls,Select TLS backend,TLS libraries,Native CA stores,OCSP stapling,Restrictions,HTTP/3 backends,<features>
• GOPHER:How it started,What protocols does curl support?,GOPHER,Supported schemes,Version,Variables
• GOPHERS:What protocols does curl support?,GOPHERS,Supported schemes,Variables

H

• Happy Eyeballs:Happy Eyeballs,All options,Happy Eyeballs
• --happy-eyeballs-timeout-ms:Tweak
• haproxy:haproxy,All options
• --haproxy-clientip:curl and haproxy
• --haproxy-protocol:curl and haproxy
• --header:Server differences,Proxy headers,JSON,Customize headers
• Header callback:All options,Header data,Response body,Download headers too
• homebrew:macOS
• Host::HTTP basics,Trace options,Change the Host: header,The HTTP this generates,Customize headers,Customize HTTP request headers
• --hsts:HSTS cache
• HSTS:HTTPS,HSTS,All options,HSTS,HSTS,HSTS,<features>
• HTTP proxy:How it started,Proxy type,HTTP proxy,Proxy headers,Authentication,All options,HTTP proxy,Available information,<proxy [nonewline="yes"]>
• HTTP redirects:Short options,Long options,Available exit codes,Tell curl to follow redirects,Submit a login form over HTTP
• HTTP Strict Transport Security:HSTS,HSTS,HSTS
• HTTP/1.1:HTTP,HTTP basics,Trace options,HTTP/2,Debugging with TELNET,HTTP/2,Caveats,The HTTP this generates,GET or POST?,Request method,Request target,Customize HTTP request headers,Versions,About content encodings
• HTTP/2:HTTP,docs,nghttp2,Line 4: Features,Available exit codes,More data,HTTP/2,HTTP/2,HTTP/3,HTTP/2 and later,GET or POST?,HTTP headers,HTTP/3,Trace more,When connections are not reused as you want,QUIC and HTTP/2,DNS over HTTPS,HTTPS proxy,Versions,Expect: headers,Multiplexing,HTTP/3,Curl_easy,Variables
• HTTP/3:HTTP,Select HTTP/3 backend,QUIC and HTTP/3,TCP vs UDP,Line 4: Features,Available exit codes,More data,HTTP/3 racing,HTTP/3,HTTP headers,HTTP/3,Which libcurl version runs,Trace more,HTTP/3,When connections are not reused as you want,Versions,Expect: headers,Multiplexing,HTTP/3,Different backends
• HTTP/3 backend:Select HTTP/3 backend,HTTP/3 backends
• --http0.9:HTTP/0.9
• --http2:HTTP/2
• --http2-prior-knowledge:HTTP/2
• --http3:HTTP/3 racing,Enable
• --http3-only:When QUIC is denied
• HttpGet:How it started
• HTTPS proxy:Line 4: Features,HTTPS proxy,All options,Local or proxy name lookup

I

• IDN:libidn2,International Domain Names (IDN),Version,CURLU_URLENCODE,Different backends,<features>
• IETF:Protocols,TLS versions
• Indentation:Indentation
• International Domain Names:libidn2,International Domain Names (IDN),Line 4: Features
• --ip-tos:Type of Service
• IPFS:IPFS
• --ipfs-gateway:Gateway
• IPv4:Host,Port number,Available --write-out variables,Type of Service,Happy Eyeballs,curl and haproxy,All options,How libcurl connects,Name resolving,host*.c sources,Variables
• IPv6:Host,Port number,URL globbing,Version,Available --write-out variables,Type of Service,Happy Eyeballs,SOCKS proxy,curl and haproxy,All options,How libcurl connects,Name resolving,Zone ID,CURLRES_IPV6,Variables
• IRC:How it started,Project communication

J

• #"usingcurl/downloads/browsers.html#client-differences">Client differences,PAC,JavaScript and forms,JavaScript redirects,Figure out what the browser does
• --json:trurl example command lines,JSON
• json:Arguments with spaces,Functions,Available --write-out variables,Content-Type,JSON,POST outside of HTML

K

• -K:Command lines, quotes and aliases,Specify the config file to use
• keep-alive:All options,Example
• --keepalive-cnt:Keep alive
• --keepalive-time:Keep alive

L

• -L:Short options,Available --write-out variables,Tell curl to follow redirects,Request method,Cookie engine,Reading cookies from file,Redirects
• LD_LIBRARY_PATH:LD_LIBRARY_PATH
• --libcurl:--libcurl
• libcurl version:Line 1: curl,Available exit codes,Which libcurl version,Network data conversion
• libidn2:libidn2
• libpsl:libpsl
• libressl:TLS libraries,Restrictions,HTTP/3 backends
• librtmp:librtmp
• libssh:SSH libraries,<features>
• libssh2:SSH libraries,<features>
• license:Finding users,License,root,License
• --limit-rate:Rate limiting
• --location:Long options,Separate options per URL,Syntax,Tell curl to follow redirects

M

• --max-filesize:Maximum filesize
• --max-time:Tweak your retries,Maximum time allowed to spend
• MIT:License
• --mptcp:Multipath TCP
• MQTT:What protocols does curl support?,MQTT,Supported schemes,Line 3: Protocols,MQTT,Variables,Test servers
• mTLS:Client certificates
• multi-threading:multi-threading
• Multipath TCP:Multipath TCP

N

• name resolving:Hostname resolving,Handling build options,Available --write-out variables,Name resolve tricks with c-ares,SOCKS proxy,Connection reuse,Name resolving,Proxy types,Available information,Different backends
• --negotiate:Network leakage,Authentication
• .netrc:Command line leakage,.netrc,All options,.netrc,<features>
• --netrc-file:Enable netrc
• --netrc-optional:Enable netrc
• nghttp2:nghttp2,Which libcurl version runs
• nix:nix
• --no-clobber:Overwriting,Use the target filename from the server
• --no-eprt:Active connections
• --no-epsv:Passive connections
• --no-keepalive:Keep alive
• NPN:All options
• --ntlm:Network leakage,Authentication

O

• -O:Many options and URLs,Numerical ranges,Download to a file named by the URL,Use the target filename from the server,Shell redirects,Multiple downloads,Resuming and ranges,Request rate limiting,For SFTP/SCP,Skip download if already done,Authentication,Download,Check by modification date
• openldap:openldap
• OpenSSL:Get curl and libcurl on MSYS2,lib/vtls,Select TLS backend,TLS libraries,Available exit codes,Native CA stores,OCSP stapling,Restrictions,All options,SSL context,Available information,HTTP/3 backends,<features>
• --output-dir:Store in another directory

P

• PAC:PAC,Which proxy?
• --parallel:Parallel transfers,Parallel progress meter,Parallel,Request rate limiting
• --parallel-immediate:Connection before multiplex
• --parallel-max:Parallel transfers
• --path-as-is:--path-as-is
• Percent-encoding:URL encode data
• pop3:What protocols does curl support?,POP3,Without scheme,Version,Available exit codes,Enable TLS,Reading email,Secure mail transfer,STARTTLS,CURLU_GUESS_SCHEME,Variables,Test servers
• port number:Connect to port numbers,The URL converted to a request,Port number,trurl example command lines,Available exit codes,Available --write-out variables,Provide a custom IP address for a name,Local port number,HTTP proxy,Historic TELNET,Enable,Converting a web form,Implicit FTPS,All options,Prereq,Local address and port number,Connection reuse,Custom addresses for hosts,Proxies,Post transfer info,CURLU_DEFAULT_PORT,Set URL parts,Alt-Svc,Base64 Encoding
• --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:All options,timer_callback,Progress information,easy API,Progress callback
• pronunciation:Pronunciation
• --proxy:HTTP proxy,Authentication
• proxy:How it started,Line 4: Features,Available exit codes,Available --write-out variables,Intermediaries' fiddlings,Discover your proxy,PAC,Proxy type,HTTP proxy,SOCKS proxy,MITM proxy,Proxy authentication,HTTPS proxy,Proxy environment variables,Proxy headers,haproxy,CONNECT response codes,Authentication,Verification,All options,Proxies,Available information,Variables
• --proxy-ca-native:Native CA stores
• --proxy-http2:HTTP/2
• --proxy-user:Proxy authentication,Authentication
• --proxy1.0:HTTP proxy tunneling
• --proxytunnel:HTTP proxy tunneling

Q

• -Q:Quote
• QUIC:Establish a connection,HTTPS,QUIC and HTTP/3,Available exit codes,Multipath TCP,HTTP/3 racing,Never spend more than this to connect,QUIC,Which libcurl version runs,HTTP/3,Enable keep alive,Authentication,Version 3 can be mandatory,HTTP/3 backends
• --quote:Quote

R

• ranges:Numerical ranges,Resuming and ranges,Skip download if already done,A range trick,Ranges,Provide a file descriptor,HTTP response code,Ranges
• --rate:Request rate limiting
• Read callback:make callbacks as fast as possible,All options,Read data,HTTP POST
• redhat:Redhat and CentOS
• redirects:Long options,Separate options per URL,Syntax,Available exit codes,Available --write-out variables,Download to a file named by the URL,Shell redirects,Provide a custom IP address for a name,Captive portals,Redirects,Request method,Redirects,All options,Custom addresses for hosts,Available information,Automatic referrer,Submit a login form over HTTP
• RELEASE-NOTES:scripts
• releases:curl-announce,Releases,Backdoors and supply chain risks,scripts,Which libcurl version
• --remote-name-all:One output for each given URL,Use the URL's filename part for all URLs
• --remove-on-error:Leftovers on errors
• repository:Releases,Backdoors and supply chain risks,Source code on GitHub,Arch Linux,Building libcurl on MSYS2,root,What to add,Website,Continuous Integration,Autobuilds,Content
• --resolve:Provide a custom IP address for a name
• --retry:Available --write-out variables,Retry,Request rate limiting
• --retry-all-errors:Retry on any and all errors
• --retry-connrefused:Connection refused
• --retry-delay:Tweak your retries
• --retry-max-time:Tweak your retries
• RFC 1436:GOPHER
• RFC 1738:FILE,multicwd
• RFC 1939:POP3
• RFC 1945:Redirects
• RFC 2229:DICT
• RFC 2246:TLS versions
• RFC 2326:RTSP
• RFC 2595:IMAP
• RFC 2616:About content encodings
• RFC 2818:HTTPS
• RFC 3207:SMTP
• RFC 3501:IMAP
• RFC 3986:Browsers
• RFC 4217:FTPS
• RFC 4511:LDAP
• RFC 5321:SMTP
• RFC 7838:Alternative Services
• RFC 8314:IMAPS
• RFC 8446:TLS versions
• RFC 854:TELNET
• RFC 8999:HTTPS
• RFC 9110:HTTP
• RFC 9112:HTTP
• RFC 9113:HTTP
• RFC 9114:HTTP
• RFC 959:FTP,Quote
• roadmap:Future
• rpath:rpath
• RTMP:What protocols does curl support?,RTMP,librtmp,Supported schemes,Version
• RTSP:What protocols does curl support?,RTSP,Supported schemes,Version,All options,RTSP interleaved data,Available information,Variables
• rustls:TLS libraries,<features>
• rustls-ffi:Select TLS backend,Rustls

S

• Safari:Copy as curl
• Schannel:TLS libraries,Native CA stores,HTTP/3 backends,<features>
• Scheme:Connect to port numbers,FILE,Naming,librtmp,Scheme,Name and password,TCP vs UDP,Browsers,Available exit codes,Available --write-out variables,Proxy type,SOCKS proxy,Proxy authentication,TLS for emails,Which libcurl version,Proxy types,Available information,Authentication,CURLU_NON_SUPPORT_SCHEME,CURLU_DEFAULT_PORT,URLs,Get a response into memory,Protocol handler,Curl_handler
• SCP:What protocols does curl support?,SCP,SSH libraries,Supported schemes,Version,Available exit codes,Protocols allowing upload,Compression,URLs,Authentication,Known hosts,All options,Authentication,Curl_handler,<server>
• security:trurl, a URL tool,curl-announce,Commercial support,Security,Trust,Security,How much do protocols change?,FTPS,docs,Reporting vulnerabilities,http_proxy in lower case only,TLS,Ciphers,Enable TLS,TLS versions,HTTP/0.9,HSTS,Protocol version,All options,HSTS,Authentication,URLs,HSTS
• SFTP:What protocols does curl support?,SFTP,SSH libraries,Supported schemes,Version,Available exit codes,Trace options,Protocols allowing upload,Compression,URLs,Authentication,Known hosts,All options,Authentication,Curl_handler,<server>,Run a range of tests
• --silent:Progress meter,Error message
• --skip-existing:Skip download if already done
• SMTP:What protocols does curl support?,SMTP,Without scheme,Version,Available exit codes,Protocols allowing upload,Enable TLS,Sending email,STARTTLS,All options,CURLU_GUESS_SCHEME,Variables,Test servers
• SMTPS:What protocols does curl support?,SMTPS,TLS libraries,Supported schemes,Version,Protocols allowing upload,Enable TLS
• snapshots:Daily snapshots,root
• SNI:Change the Host: header
• --socks4:SOCKS proxy
• --socks4a:SOCKS proxy
• --socks5:SOCKS proxy
• --socks5-hostname:SOCKS proxy
• --speed-limit:Stop slow transfers
• --speed-time:Stop slow transfers
• SSH:SCP,Select SSH backend,SSH libraries,Available exit codes,Authentication,Known hosts,Historic TELNET,Trace everything,All options,SSH key,Authentication,Different backends,Curl_handler,Variables
• SSH backend:Select SSH backend
• SSL context callback:All options
• SSLKEYLOGFILE:TLS,SSLKEYLOGFILE,Figure out what a browser sends
• STARTTLS:IMAP,TLS for emails,STARTTLS

T

• -T:PUT,Upload,Method,HTTP PUT,Uploading with FTP
• TCP:Establish a connection,How much do protocols change?,DICT,TCP vs UDP,Available exit codes,Available --write-out variables,Multipath TCP,Connection timeout,HTTP/3 racing,Local port number,Keep alive,Timeouts,HTTP proxy tunneling,MITM proxy,haproxy,TLS,Debugging with TELNET,TFTP,QUIC,HTTPS,Two connections,Connection cache,All options,HTTP/3,Keep alive,connectdata
• TELNET:What protocols does curl support?,TELNET,Supported schemes,Version,Available exit codes,TELNET,All options,Variables
• testing:What does curl do?,Reporting bugs,Handling build options,Contributing,Run a local clone,Separate install,About HTTP response code "errors",Debug builds,Test servers,Torture
• TFTP:What protocols does curl support?,TFTP,Supported schemes,TCP vs UDP,Version,Available exit codes,Protocols allowing upload,TFTP,All options,Variables,Test servers
• --tftp-blksize:TFTP options
• --tftp-no-options:TFTP options
• --time-cond:Check by modification date
• TLS:Security,How much do protocols change?,GOPHERS,The URL converted to a request,Ubuntu and Debian,lib/vtls,Handling build options,Select TLS backend,TLS libraries,TLS libraries,Line 1: curl,Available exit codes,More data,Available --write-out variables,Change the Host: header,Never spend more than this to connect,MITM proxy,TLS,Ciphers,Enable TLS,TLS versions,Verifying server certificates,Certificate pinning,OCSP stapling,Client certificates,TLS auth,TLS backends,SSLKEYLOGFILE,Known hosts,TLS for emails,Caveats,HTTPS only,Figure out what a browser sends,HTTPS,TLS fingerprinting,FTPS,Trace everything,Caches,reuse handles,TLS options,All options,SSL context,HTTP proxy,Authentication,Available information,URLs,Different backends,connection cache,Variables
• TLS backend:Ubuntu and Debian,lib/vtls,Select TLS backend,Line 1: curl,Available exit codes,TLS,Native CA stores,Certificate pinning,OCSP stapling,Client certificates,TLS backends,CA cert cache,CA store caching,SSL context
• TODO:Future,Suggestions
• --tr-encoding:Transfer encoding,Compression
• --trace:Trace options,<command [option="no-output/no-include/force-output/binary-trace"] [timeout="secs"][delay="secs"][type="perl/shell"]>
• --trace-ascii:Trace options,Server differences,<command [option="no-output/no-include/force-output/binary-trace"] [timeout="secs"][delay="secs"][type="perl/shell"]>
• --trace-config:More data
• --trace-ids:Identify transfers and connections
• --trace-time:Time stamps
• Traffic Class:Type of Service
• transfer-encoding:Pass on transfer encoding,Chunked encoded POSTs
• trurl:What does curl do?,trurl
• Type of Service:Type of Service

U

• -U:Building libcurl on MSYS2,Help with a specific option,Proxy authentication
• -u:Building libcurl on MSYS2,Passwords,URLs,Authentication,IMAP,Authentication
• Ubuntu:Ubuntu and Debian
• URL Globbing:URL globbing
• URL parser:trurl, a URL tool,Browsers,trurl,CURLU_ALLOW_SPACE
• --url-query:Query

V

• --variable:Variables
• variables:No assignments in conditions,Output variables for globbing,Config file,Variables,Error message,Write out,Proxy environment variables,Ciphers,Proxy environment variables,Preprocessed
• --verbose:Long options,Time stamps
• --version:Version,TLS backends,Memory debugging
• --vlan-priority:VLAN
• Vulnerability:Backdoors and supply chain risks,Vulnerability handling

W

• wcurl:What does curl do?
• Wireshark:Available exit codes,Trace options,SSLKEYLOGFILE,Figure out what a browser sends
• wolfSSH:SSH libraries,<features>
• wolfSSL:Commercial support,lib/vtls,TLS libraries,Native CA stores,Restrictions,All options,SSL context,HTTP/3 backends,<features>
• Write callback:make callbacks as fast as possible,Callback considerations,All options,Write data,Response body,1. The callback approach,Raw mode,Write callback,Get a simple HTTP page,Get a response into memory
• --write-out:Error message,Write out,Overwriting,HTTP response codes

X

• -X:HTTP PUT,Request method,Request target
• -x:HTTP proxy,SOCKS proxy,Proxy authentication,Proxy environment variables,Proxy headers,Proxy environment variables

Y

• yum:Redhat and CentOS

Z

• -Z:Parallel transfers,Parallel
• -z:Check by modification date
• zlib:HTTP Compression,About content encodings
• zstd:HTTP Compression,Which libcurl version runs,Supported content encodings