(SMTP) Specify a single email address, username or mailing list name. Repeat this option several times to send to multiple recipients.

When performing an address verification (VRFY command), the recipient should be specified as the username or username and domain (as per Section 3.5 of RFC 5321).

When performing a mailing list expand (EXPN command), the recipient should be specified using the mailing list name, such as "Friends" or "London-Office".

--mail-rcpt can be used several times in a command line

Example:

curl --mail-rcpt user@example.net smtp://example.com

See also --mail-rcpt-allowfails.

--mail-rcpt-allowfails

(SMTP) When sending data to multiple recipients, by default curl aborts SMTP conversation if at least one of the recipients causes RCPT TO command to return an error.

The default behavior can be changed by passing --mail-rcpt-allowfails command-line option which makes curl ignore errors and proceed with the remaining valid recipients.

If all recipients trigger RCPT TO failures and this flag is specified, curl still aborts the SMTP conversation and returns the error received from to the last RCPT TO command.

Providing --mail-rcpt-allowfails multiple times has no extra effect. Disable it again with --no-mail-rcpt-allowfails.

Example:

curl --mail-rcpt-allowfails --mail-rcpt dest@example.com smtp://example.com

Added in 7.69.0. See also --mail-rcpt.

-M, --manual

Manual. Display the huge help text.

Example:

curl --manual

See also -v, --verbose, --libcurl and --trace.

--max-filesize

(FTP HTTP MQTT) When set to a non-zero value, it specifies the maximum size (in bytes) of a file to download. If the file requested is larger than this value, the transfer does not start and curl returns with exit code 63.

Setting the maximum value to zero disables the limit.

A size modifier may be used. For example, Appending 'k' or 'K' counts the number as kilobytes, 'm' or 'M' makes it megabytes, while 'g' or 'G' makes it gigabytes. Examples: 200K, 3m and 1G.

NOTE: before curl 8.4.0, when the file size is not known prior to download, for such files this option has no effect even if the file transfer ends up being larger than this given limit.

Starting with curl 8.4.0, this option aborts the transfer if it reaches the threshold during transfer.

If --max-filesize is provided several times, the last set value is used.

Example:

curl --max-filesize 100K https://example.com

See also --limit-rate.

--max-redirs

(HTTP) Set maximum number of redirections to follow. When -L, --location is used, to prevent curl from following too many redirects, by default, the limit is set to 50 redirects. Set this option to -1 to make it unlimited.

If --max-redirs is provided several times, the last set value is used.

Example:

curl --max-redirs 3 --location https://example.com

See also -L, --location.

-m, --max-time

Set maximum time in seconds that you allow each transfer to take. Prevents your batch jobs from hanging for hours due to slow networks or links going down. This option accepts decimal values.

If you enable retrying the transfer (--retry) then the maximum time counter is reset each time the transfer is retried. You can use --retry-max-time to limit the retry time.

The decimal value needs to be provided using a dot (.) as decimal separator - not the local version even if it might be using another separator.

If --max-time is provided several times, the last set value is used.

Examples:

curl --max-time 10 https://example.com curl --max-time 2.92 https://example.com

See also --connect-timeout and --retry-max-time.

--metalink

This option was previously used to specify a Metalink resource. Metalink support is disabled in curl for security reasons (added in 7.78.0).

If --metalink is provided several times, the last set value is used.

Example:

curl --metalink file https://example.com

See also -Z, --parallel.

--mptcp

Enables the use of Multipath TCP (MPTCP) for connections. MPTCP is an extension to the standard TCP that allows multiple TCP streams over different network paths between the same source and destination. This can enhance bandwidth and improve reliability by using multiple paths simultaneously.

MPTCP is beneficial in networks where multiple paths exist between clients and servers, such as mobile networks where a device may switch between WiFi and cellular data or in wired networks with multiple Internet Service Providers.

This option is currently only supported on Linux starting from kernel 5.6. Only TCP connections are modified, hence this option does not effect HTTP/3 (QUIC) or UDP connections.

The server curl connects to must also support MPTCP. If not, the connection seamlessly falls back to TCP.

Providing --mptcp multiple times has no extra effect. Disable it again with --no-mptcp.

Example:

curl --mptcp https://example.com

Added in 8.9.0. See also --tcp-fastopen.

--negotiate

(HTTP) Enable Negotiate (SPNEGO) authentication.

This option requires a library built with GSS-API or SSPI support. Use -V, --version to see if your curl supports GSS-API/SSPI or SPNEGO.

When using this option, you must also provide a fake -u, --user option to activate the authentication code properly. Sending a '-u :' is enough as the username and password from the -u, --user option are not actually used.

Providing --negotiate multiple times has no extra effect.

Example:

curl --negotiate -u : https://example.com

See also --basic, --ntlm, --anyauth and --proxy-negotiate.

-n, --netrc

Make curl scan the .netrc file in the user's home directory for login name and password. This is typically used for FTP on Unix. If used with HTTP, curl enables user authentication. See netrc(5) and ftp(1) for details on the file format. Curl does not complain if that file does not have the right permissions (it should be neither world- nor group-readable). The environment variable "HOME" is used to find the home directory.

On Windows two filenames in the home directory are checked: .netrc and _netrc, preferring the former. Older versions on Windows checked for _netrc only.

A quick and simple example of how to setup a .netrc to allow curl to FTP to the machine host.domain.com with username 'myself' and password 'secret' could look similar to:

machine host.domain.com login myself password secret

Providing --netrc multiple times has no extra effect. Disable it again with --no-netrc.

Example:

curl --netrc https://example.com

This option is mutually exclusive with --netrc-file and --netrc-optional. See also --netrc-file, -K, --config and -u, --user.

--netrc-file

Set the netrc file to use. Similar to -n, --netrc, except that you also provide the path (absolute or relative).

It abides by --netrc-optional if specified.

If --netrc-file is provided several times, the last set value is used.

Example:

curl --netrc-file netrc https://example.com

This option is mutually exclusive with -n, --netrc. See also -n, --netrc, -u, --user and -K, --config.

--netrc-optional

Similar to -n, --netrc, but this option makes the .netrc usage optional and not mandatory as the -n, --netrc option does.

Providing --netrc-optional multiple times has no extra effect. Disable it again with --no-netrc-optional.

Example:

curl --netrc-optional https://example.com

This option is mutually exclusive with -n, --netrc. See also --netrc-file.

-:, --next

Use a separate operation for the following URL and associated options. This allows you to send several URL requests, each with their own specific options, for example, such as different usernames or custom requests for each.

-:, --next resets all local options and only global ones have their values survive over to the operation following the -:, --next instruction. Global options include -v, --verbose, --trace, --trace-ascii and --fail-early.

For example, you can do both a GET and a POST in a single command line:

curl www1.example.com --next -d postthis www2.example.com

--next can be used several times in a command line

Examples:

curl https://example.com --next -d postthis www2.example.com curl -I https://example.com --next https://example.net/

See also -Z, --parallel and -K, --config.

--no-alpn

(HTTPS) Disable the ALPN TLS extension. ALPN is enabled by default if libcurl was built with an SSL library that supports ALPN. ALPN is used by a libcurl that supports HTTP/2 to negotiate HTTP/2 support with the server during https sessions.

Note that this is the negated option name documented. You can use --alpn to enable ALPN.

Providing --no-alpn multiple times has no extra effect. Disable it again with --alpn.

Example:

curl --no-alpn https://example.com

--no-alpn requires that libcurl is built to support TLS. See also --no-npn and --http2.

-N, --no-buffer

Disables the buffering of the output stream. In normal work situations, curl uses a standard buffered output stream that has the effect that it outputs the data in chunks, not necessarily exactly when the data arrives. Using this option disables that buffering.

Note that this is the negated option name documented. You can use --buffer to enable buffering again.

Providing --no-buffer multiple times has no extra effect. Disable it again with --buffer.

Example:

curl --no-buffer https://example.com

See also -#, --progress-bar.

--no-clobber

When used in conjunction with the -o, --output, -J, --remote-header-name, -O, --remote-name, or --remote-name-all options, curl avoids overwriting files that already exist. Instead, a dot and a number gets appended to the name of the file that would be created, up to filename.100 after which it does not create any file.

Note that this is the negated option name documented. You can thus use --clobber to enforce the clobbering, even if -J, --remote-header-name is specified.

Providing --no-clobber multiple times has no extra effect. Disable it again with --clobber.

Example:

curl --no-clobber --output local/dir/file https://example.com

Added in 7.83.0. See also -o, --output and -O, --remote-name.

--no-keepalive

Disables the use of keepalive messages on the TCP connection. curl otherwise enables them by default.

Note that this is the negated option name documented. You can thus use --keepalive to enforce keepalive.

Providing --no-keepalive multiple times has no extra effect. Disable it again with --keepalive.

Example:

curl --no-keepalive https://example.com

See also --keepalive-time and --keepalive-cnt.

--no-npn

(HTTPS) curl never uses NPN, this option has no effect (added in 7.86.0).

Disable the NPN TLS extension. NPN is enabled by default if libcurl was built with an SSL library that supports NPN. NPN is used by a libcurl that supports HTTP/2 to negotiate HTTP/2 support with the server during https sessions.

Providing --no-npn multiple times has no extra effect. Disable it again with --npn.

Example:

curl --no-npn https://example.com

--no-npn requires that libcurl is built to support TLS. See also --no-alpn and --http2.

--no-progress-meter

Option to switch off the progress meter output without muting or otherwise affecting warning and informational messages like -s, --silent does.

Note that this is the negated option name documented. You can thus use --progress-meter to enable the progress meter again.

Providing --no-progress-meter multiple times has no extra effect. Disable it again with --progress-meter.

Example:

curl --no-progress-meter -o store https://example.com

Added in 7.67.0. See also -v, --verbose and -s, --silent.

--no-sessionid

(TLS) Disable curl's use of SSL session-ID caching. By default all transfers are done using the cache. Note that while nothing should ever get hurt by attempting to reuse SSL session-IDs, there seem to be broken SSL implementations in the wild that may require you to disable this in order for you to succeed.

Note that this is the negated option name documented. You can thus use --sessionid to enforce session-ID caching.

Providing --no-sessionid multiple times has no extra effect. Disable it again with --sessionid.

Example:

curl --no-sessionid https://example.com

See also -k, --insecure.

--noproxy

Comma-separated list of hosts for which not to use a proxy, if one is specified. The only wildcard is a single "*" character, which matches all hosts, and effectively disables the proxy. Each name in this list is matched as either a domain which contains the hostname, or the hostname itself. For example, "local.com" would match "local.com", "local.com:80", and "www.local.com", but not "www.notlocal.com".

This option overrides the environment variables that disable the proxy ("no_proxy" and "NO_PROXY"). If there is an environment variable disabling a proxy, you can set the no proxy list to "" to override it.

IP addresses specified to this option can be provided using CIDR notation (added in 7.86.0): an appended slash and number specifies the number of network bits out of the address to use in the comparison. For example "192.168.0.0/16" would match all addresses starting with "192.168".

If --noproxy is provided several times, the last set value is used.

Example:

curl --noproxy "www.example" https://example.com

See also -x, --proxy.

--ntlm

(HTTP) Use NTLM authentication. The NTLM authentication method was designed by Microsoft and is used by IIS web servers. It is a proprietary protocol, reverse-engineered by clever people and implemented in curl based on their efforts. This kind of behavior should not be endorsed, you should encourage everyone who uses NTLM to switch to a public and documented authentication method instead, such as Digest.

If you want to enable NTLM for your proxy authentication, then use --proxy-ntlm.

Providing --ntlm multiple times has no extra effect.

Example:

curl --ntlm -u user:password https://example.com

--ntlm requires that libcurl is built to support TLS. This option is mutually exclusive with --basic, --negotiate, --digest and --anyauth. See also --proxy-ntlm.

--ntlm-wb

(HTTP) Deprecated option (added in 8.8.0).

Enabled NTLM much in the style --ntlm does, but handed over the authentication to a separate executable that was executed when needed.

Providing --ntlm-wb multiple times has no extra effect.

Example:

curl --ntlm-wb -u user:password https://example.com

See also --ntlm and --proxy-ntlm.

--oauth2-bearer

(IMAP LDAP POP3 SMTP HTTP) Specify the Bearer Token for OAUTH 2.0 server authentication. The Bearer Token is used in conjunction with the username which can be specified as part of the --url or -u, --user options.

The Bearer Token and username are formatted according to RFC 6750.

If --oauth2-bearer is provided several times, the last set value is used.

Example:

curl --oauth2-bearer "mF_9.B5f-4.1JqM" https://example.com

See also --basic, --ntlm and --digest.

-o, --output

Write output to the given file instead of stdout. If you are using globbing to fetch multiple documents, you should quote the URL and you can use "#" followed by a number in the filename. That variable is then replaced with the current string for the URL being fetched. Like in:

curl "http://{one,two}.example.com" -o "file_#1.txt"

or use several variables like:

curl "http://{site,host}.host[1-5].example" -o "#1_#2"

You may use this option as many times as the number of URLs you have. For example, if you specify two URLs on the same command line, you can use it like this:

curl -o aa example.com -o bb example.net

and the order of the -o options and the URLs does not matter, just that the first -o is for the first URL and so on, so the above command line can also be written as

curl example.com example.net -o aa -o bb

See also the --create-dirs option to create the local directories dynamically. Specifying the output as '-' (a single dash) passes the output to stdout.

To suppress response bodies, you can redirect output to /dev/null:

curl example.com -o /dev/null

Or for Windows:

curl example.com -o nul

Specify the filename as single minus to force the output to stdout, to override curl's internal binary output in terminal prevention:

curl https://example.com/jpeg -o -

--output is associated with a single URL. Use it once per URL when you use several URLs in a command line.

Examples:

curl -o file https://example.com curl "http://{one,two}.example.com" -o "file_#1.txt" curl "http://{site,host}.host[1-5].example" -o "#1_#2" curl -o file https://example.com -o file2 https://example.net

See also -O, --remote-name, --remote-name-all and -J, --remote-header-name.

--output-dir

Specify the directory in which files should be stored, when -O, --remote-name or -o, --output are used.

The given output directory is used for all URLs and output options on the command line, up until the first -:, --next.

If the specified target directory does not exist, the operation fails unless --create-dirs is also used.

If --output-dir is provided several times, the last set value is used.

Example:

curl --output-dir "tmp" -O https://example.com

Added in 7.73.0. See also -O, --remote-name and -J, --remote-header-name.

-Z, --parallel

Makes curl perform all transfers in parallel as compared to the regular serial manner. Parallel transfer means that curl runs up to N concurrent transfers simultaneously and if there are more than N transfers to handle, it starts new ones when earlier transfers finish.

With parallel transfers, the progress meter output is different than when doing serial transfers, as it then displays the transfer status for multiple transfers in a single line.

The maximum amount of concurrent transfers is set with --parallel-max and it defaults to 50.

This option is global and does not need to be specified for each use of --next.

Providing --parallel multiple times has no extra effect. Disable it again with --no-parallel.

Example:

curl --parallel https://example.com -o file1 https://example.com -o file2

Added in 7.66.0. See also -:, --next, -v, --verbose, --parallel-max and --parallel-immediate.

--parallel-immediate

When doing parallel transfers, this option instructs curl to prefer opening up more connections in parallel at once rather than waiting to see if new transfers can be added as multiplexed streams on another connection.

By default, without this option set, curl prefers to wait a little and multiplex new transfers over existing connections. It keeps the number of connections low at the expense of risking a slightly slower transfer startup.

This option is global and does not need to be specified for each use of --next.

Providing --parallel-immediate multiple times has no extra effect. Disable it again with --no-parallel-immediate.

Example:

curl --parallel-immediate -Z https://example.com -o file1 https://example.com -o file2

Added in 7.68.0. See also -Z, --parallel and --parallel-max.

--parallel-max

When asked to do parallel transfers, using -Z, --parallel, this option controls the maximum amount of transfers to do simultaneously.

The default is 50. 300 is the largest supported value.

This option is global and does not need to be specified for each use of --next.

If --parallel-max is provided several times, the last set value is used.

Example:

curl --parallel-max 100 -Z https://example.com ftp://example.com/

Added in 7.66.0. See also -Z, --parallel.

--pass

(SSH TLS) Passphrase for the private key.

If --pass is provided several times, the last set value is used.

Example:

curl --pass secret --key file https://example.com

See also --key and -u, --user.

--path-as-is

Do not handle sequences of /../ or /./ in the given URL path. Normally curl squashes or merges them according to standards but with this option set you tell it not to do that.

Providing --path-as-is multiple times has no extra effect. Disable it again with --no-path-as-is.

Example:

curl --path-as-is https://example.com/../../etc/passwd

See also --request-target.

--pinnedpubkey

(TLS) Use the specified public key file (or hashes) to verify the peer. This can be a path to a file which contains a single public key in PEM or DER format, or any number of base64 encoded sha256 hashes preceded by 'sha256//' and separated by ';'.

When negotiating a TLS or SSL connection, the server sends a certificate indicating its identity. A public key is extracted from this certificate and if it does not exactly match the public key provided to this option, curl aborts the connection before sending or receiving any data.

This option is independent of option -k, --insecure. If you use both options together then the peer is still verified by public key.

PEM/DER support:

OpenSSL and GnuTLS, wolfSSL, mbedTLS , Secure Transport macOS 10.7+/iOS 10+, Schannel

sha256 support:

OpenSSL, GnuTLS and wolfSSL, mbedTLS, Secure Transport macOS 10.7+/iOS 10+, Schannel

Other SSL backends not supported.

If --pinnedpubkey is provided several times, the last set value is used.

Examples:

curl --pinnedpubkey keyfile https://example.com curl --pinnedpubkey 'sha256//ce118b51897f4452dc' https://example.com

See also --hostpubsha256.

--post301

(HTTP) Respect RFC 7231/6.4.2 and do not convert POST requests into GET requests when following a 301 redirect. The non-RFC behavior is ubiquitous in web browsers, so curl does the conversion by default to maintain consistency. However, a server may require a POST to remain a POST after such a redirection. This option is meaningful only when using -L, --location.

Providing --post301 multiple times has no extra effect. Disable it again with --no-post301.

Example:

curl --post301 --location -d "data" https://example.com

See also --post302, --post303 and -L, --location.

--post302

(HTTP) Respect RFC 7231/6.4.3 and do not convert POST requests into GET requests when following a 302 redirect. The non-RFC behavior is ubiquitous in web browsers, so curl does the conversion by default to maintain consistency. However, a server may require a POST to remain a POST after such a redirection. This option is meaningful only when using -L, --location.

Providing --post302 multiple times has no extra effect. Disable it again with --no-post302.

Example:

curl --post302 --location -d "data" https://example.com

See also --post301, --post303 and -L, --location.

--post303

(HTTP) Violate RFC 7231/6.4.4 and do not convert POST requests into GET requests when following 303 redirect. A server may require a POST to remain a POST after a 303 redirection. This option is meaningful only when using -L, --location.

Providing --post303 multiple times has no extra effect. Disable it again with --no-post303.

Example:

curl --post303 --location -d "data" https://example.com

See also --post302, --post301 and -L, --location.

--preproxy [protocol://]host[:port]

Use the specified SOCKS proxy before connecting to an HTTP or HTTPS -x, --proxy. In such a case curl first connects to the SOCKS proxy and then connects (through SOCKS) to the HTTP or HTTPS proxy. Hence pre proxy.

The pre proxy string should be specified with a protocol:// prefix to specify alternative proxy protocols. Use socks4://, socks4a://, socks5:// or socks5h:// to request the specific SOCKS version to be used. No protocol specified makes curl default to SOCKS4.

If the port number is not specified in the proxy string, it is assumed to be 1080.

User and password that might be provided in the proxy string are URL decoded by curl. This allows you to pass in special characters such as @ by using %40 or pass in a colon with %3a.

If --preproxy is provided several times, the last set value is used.

Example:

curl --preproxy socks5://proxy.example -x http://http.example https://example.com

See also -x, --proxy and --socks5.

-#, --progress-bar

Make curl display transfer progress as a simple progress bar instead of the standard, more informational, meter.

This progress bar draws a single line of '#' characters across the screen and shows a percentage if the transfer size is known. For transfers without a known size, there is a space ship (-=o=-) that moves back and forth but only while data is being transferred, with a set of flying hash sign symbols on top.

This option is global and does not need to be specified for each use of --next.

Providing --progress-bar multiple times has no extra effect. Disable it again with --no-progress-bar.

Example:

curl -# -O https://example.com

See also --styled-output.

--proto

Limit what protocols to allow for transfers. Protocols are evaluated left to right, are comma separated, and are each a protocol name or 'all', optionally prefixed by zero or more modifiers. Available modifiers are:

+

Permit this protocol in addition to protocols already permitted (this is the default if no modifier is used).

-

Deny this protocol, removing it from the list of protocols already permitted.

=

Permit only this protocol (ignoring the list already permitted), though subject to later modification by subsequent entries in the comma separated list.

For example: --proto -ftps uses the default protocols, but disables ftps

--proto -all,https,+http only enables http and https

--proto =http,https also only enables http and https

Unknown and disabled protocols produce a warning. This allows scripts to safely rely on being able to disable potentially dangerous protocols, without relying upon support for that protocol being built into curl to avoid an error.

This option can be used multiple times, in which case the effect is the same as concatenating the protocols into one instance of the option.

If --proto is provided several times, the last set value is used.

Example:

curl --proto =http,https,sftp https://example.com

See also --proto-redir and --proto-default.

--proto-default

Use protocol for any provided URL missing a scheme.

An unknown or unsupported protocol causes error CURLE_UNSUPPORTED_PROTOCOL.

This option does not change the default proxy protocol (http).

Without this option set, curl guesses protocol based on the hostname, see --url for details.

If --proto-default is provided several times, the last set value is used.

Example:

curl --proto-default https ftp.example.com

See also --proto and --proto-redir.

--proto-redir

Limit what protocols to allow on redirects. Protocols denied by --proto are not overridden by this option. See --proto for how protocols are represented.

Example, allow only HTTP and HTTPS on redirect:

curl --proto-redir -all,http,https http://example.com

By default curl only allows HTTP, HTTPS, FTP and FTPS on redirects (added in 7.65.2). Specifying all or +all enables all protocols on redirects, which is not good for security.

If --proto-redir is provided several times, the last set value is used.

Example:

curl --proto-redir =http,https https://example.com

See also --proto.

-x, --proxy [protocol://]host[:port]

Use the specified proxy.

The proxy string can be specified with a protocol:// prefix. No protocol specified or http:// it is treated as an HTTP proxy. Use socks4://, socks4a://, socks5:// or socks5h:// to request a specific SOCKS version to be used.

Unix domain sockets are supported for socks proxy. Set localhost for the host part. e.g. socks5h://localhost/path/to/socket.sock

HTTPS proxy support works set with the https:// protocol prefix for OpenSSL and GnuTLS. It also works for BearSSL, mbedTLS, Rustls, Schannel, Secure Transport and wolfSSL (added in 7.87.0).

Unrecognized and unsupported proxy protocols cause an error. Ancient curl versions ignored unknown schemes and used http:// instead.

If the port number is not specified in the proxy string, it is assumed to be 1080.

This option overrides existing environment variables that set the proxy to use. If there is an environment variable setting a proxy, you can set proxy to "" to override it.

All operations that are performed over an HTTP proxy are transparently converted to HTTP. It means that certain protocol specific operations might not be available. This is not the case if you can tunnel through the proxy, as one with the -p, --proxytunnel option.

User and password that might be provided in the proxy string are URL decoded by curl. This allows you to pass in special characters such as @ by using %40 or pass in a colon with %3a.

The proxy host can be specified the same way as the proxy environment variables, including the protocol prefix (http://) and the embedded user + password.

When a proxy is used, the active FTP mode as set with -P, --ftp-port, cannot be used.

Doing FTP over an HTTP proxy without -p, --proxytunnel makes curl do HTTP with an FTP URL over the proxy. For such transfers, common FTP specific options do not work, including --ftp-ssl-reqd and --ftp-ssl-control.

If --proxy is provided several times, the last set value is used.

Example:

curl --proxy http://proxy.example https://example.com

See also --socks5 and --proxy-basic.

--proxy-anyauth

Automatically pick a suitable authentication method when communicating with the given HTTP proxy. This might cause an extra request/response round-trip.

Providing --proxy-anyauth multiple times has no extra effect.

Example:

curl --proxy-anyauth --proxy-user user:passwd -x proxy https://example.com

See also -x, --proxy, --proxy-basic and --proxy-digest.

--proxy-basic

Use HTTP Basic authentication when communicating with the given proxy. Use --basic for enabling HTTP Basic with a remote host. Basic is the default authentication method curl uses with proxies.

Providing --proxy-basic multiple times has no extra effect.

Example:

curl --proxy-basic --proxy-user user:passwd -x proxy https://example.com

See also -x, --proxy, --proxy-anyauth and --proxy-digest.

--proxy-ca-native

(TLS) Use the CA store from the native operating system to verify the HTTPS proxy. By default, curl uses a CA store provided in a single file or directory, but when using this option it interfaces the operating system's own vault.

This option works for curl on Windows when built to use OpenSSL, wolfSSL (added in 8.3.0) or GnuTLS (added in 8.5.0). When curl on Windows is built to use Schannel, this feature is implied and curl then only uses the native CA store.

Providing --proxy-ca-native multiple times has no extra effect. Disable it again with --no-proxy-ca-native.

Example:

curl --proxy-ca-native https://example.com

Added in 8.2.0. See also --cacert, --capath, --dump-ca-embed and -k, --insecure.

--proxy-cacert

Use the specified certificate file to verify the HTTPS proxy. The file may contain multiple CA certificates. The certificate(s) must be in PEM format.

This allows you to use a different trust for the proxy compared to the remote server connected to via the proxy.

Equivalent to --cacert but used in HTTPS proxy context.

If --proxy-cacert is provided several times, the last set value is used.

Example:

curl --proxy-cacert CA-file.txt -x https://proxy https://example.com

See also --proxy-capath, --cacert, --capath, --dump-ca-embed and -x, --proxy.

--proxy-capath

Same as --capath but used in HTTPS proxy context.

Use the specified certificate directory to verify the proxy. Multiple paths can be provided by separated with colon (":") (e.g. "path1:path2:path3"). The certificates must be in PEM format, and if curl is built against OpenSSL, the directory must have been processed using the c_rehash utility supplied with OpenSSL. Using --proxy-capath can allow OpenSSL-powered curl to make SSL-connections much more efficiently than using --proxy-cacert if the --proxy-cacert file contains many CA certificates.

If this option is set, the default capath value is ignored.

If --proxy-capath is provided several times, the last set value is used.

Example:

curl --proxy-capath /local/directory -x https://proxy https://example.com

See also --proxy-cacert, -x, --proxy, --capath and --dump-ca-embed.

--proxy-cert <cert[:passwd]>

Use the specified client certificate file when communicating with an HTTPS proxy. The certificate must be in PKCS#12 format if using Secure Transport, or PEM format if using any other engine. If the optional password is not specified, it is queried for on the terminal. Use --proxy-key to provide the private key.

This option is the equivalent to -E, --cert but used in HTTPS proxy context.

If --proxy-cert is provided several times, the last set value is used.

Example:

curl --proxy-cert file -x https://proxy https://example.com

See also -x, --proxy, --proxy-key and --proxy-cert-type.

--proxy-cert-type

Set type of the provided client certificate when using HTTPS proxy. PEM, DER, ENG and P12 are recognized types.

The default type depends on the TLS backend and is usually PEM, however for Secure Transport and Schannel it is P12. If --proxy-cert is a pkcs11: URI then ENG is the default type.

Equivalent to --cert-type but used in HTTPS proxy context.

If --proxy-cert-type is provided several times, the last set value is used.

Example:

curl --proxy-cert-type PEM --proxy-cert file -x https://proxy https://example.com

See also --proxy-cert and --proxy-key.

--proxy-ciphers

(TLS) Same as --ciphers but used in HTTPS proxy context.

Specify which cipher suites to use in the connection to your HTTPS proxy when it negotiates TLS 1.2 (1.1, 1.0). The list of ciphers suites must specify valid ciphers. Read up on cipher suite details on this URL:

https://curl.se/docs/ssl-ciphers.html

If --proxy-ciphers is provided several times, the last set value is used.

Example:

curl --proxy-ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256 -x https://proxy https://example.com

See also --proxy-tls13-ciphers, --ciphers and -x, --proxy.

--proxy-crlfile

Provide filename for a PEM formatted file with a Certificate Revocation List that specifies peer certificates that are considered revoked when communicating with an HTTPS proxy.

Equivalent to --crlfile but only used in HTTPS proxy context.

If --proxy-crlfile is provided several times, the last set value is used.

Example:

curl --proxy-crlfile rejects.txt -x https://proxy https://example.com

See also --crlfile and -x, --proxy.

--proxy-digest

Use HTTP Digest authentication when communicating with the given proxy. Use --digest for enabling HTTP Digest with a remote host.

Providing --proxy-digest multiple times has no extra effect.

Example:

curl --proxy-digest --proxy-user user:passwd -x proxy https://example.com

See also -x, --proxy, --proxy-anyauth and --proxy-basic.

--proxy-header <header/@file>

(HTTP) Extra header to include in the request when sending HTTP to a proxy. You may specify any number of extra headers. This is the equivalent option to -H, --header but is for proxy communication only like in CONNECT requests when you want a separate header sent to the proxy to what is sent to the actual remote host.

curl makes sure that each header you add/replace is sent with the proper end-of-line marker, you should thus not add that as a part of the header content: do not add newlines or carriage returns, they only mess things up for you.

Headers specified with this option are not included in requests that curl knows are not be sent to a proxy.

This option can take an argument in @filename style, which then adds a header for each line in the input file. Using @- makes curl read the headers from stdin.

This option can be used multiple times to add/replace/remove multiple headers.

--proxy-header can be used several times in a command line

Examples:

curl --proxy-header "X-First-Name: Joe" -x http://proxy https://example.com curl --proxy-header "User-Agent: surprise" -x http://proxy https://example.com curl --proxy-header "Host:" -x http://proxy https://example.com

See also -x, --proxy.

--proxy-http2

(HTTP) Negotiate HTTP/2 with an HTTPS proxy. The proxy might still only offer HTTP/1 and then curl sticks to using that version.

This has no effect for any other kinds of proxies.

Providing --proxy-http2 multiple times has no extra effect. Disable it again with --no-proxy-http2.

Example:

curl --proxy-http2 -x proxy https://example.com

--proxy-http2 requires that libcurl is built to support HTTP/2. Added in 8.1.0. See also -x, --proxy.

--proxy-insecure

Same as -k, --insecure but used in HTTPS proxy context.

Every secure connection curl makes is verified to be secure before the transfer takes place. This option makes curl skip the verification step with a proxy and proceed without checking.

When this option is not used for a proxy using HTTPS, curl verifies the proxy's TLS certificate before it continues: that the certificate contains the right name which matches the hostname and that the certificate has been signed by a CA certificate present in the cert store. See this online resource for further details: https://curl.se/docs/sslcerts.html

WARNING: using this option makes the transfer to the proxy insecure.

Providing --proxy-insecure multiple times has no extra effect. Disable it again with --no-proxy-insecure.

Example:

curl --proxy-insecure -x https://proxy https://example.com

See also -x, --proxy and -k, --insecure.

--proxy-key

Specify the filename for your private key when using client certificates with your HTTPS proxy. This option is the equivalent to --key but used in HTTPS proxy context.

If --proxy-key is provided several times, the last set value is used.

Example:

curl --proxy-key here -x https://proxy https://example.com

See also --proxy-key-type and -x, --proxy.

--proxy-key-type

Specify the private key file type your --proxy-key provided private key uses. DER, PEM, and ENG are supported. If not specified, PEM is assumed.

Equivalent to --key-type but used in HTTPS proxy context.

If --proxy-key-type is provided several times, the last set value is used.

Example:

curl --proxy-key-type DER --proxy-key here -x https://proxy https://example.com

See also --proxy-key and -x, --proxy.

--proxy-negotiate

Use HTTP Negotiate (SPNEGO) authentication when communicating with the given proxy. Use --negotiate for enabling HTTP Negotiate (SPNEGO) with a remote host.

Providing --proxy-negotiate multiple times has no extra effect.

Example:

curl --proxy-negotiate --proxy-user user:passwd -x proxy https://example.com

See also --proxy-anyauth, --proxy-basic and --proxy-service-name.

--proxy-ntlm

Use HTTP NTLM authentication when communicating with the given proxy. Use --ntlm for enabling NTLM with a remote host.

Providing --proxy-ntlm multiple times has no extra effect.

Example:

curl --proxy-ntlm --proxy-user user:passwd -x http://proxy https://example.com

See also --proxy-negotiate, --proxy-anyauth and -U, --proxy-user.

--proxy-pass

Passphrase for the private key for HTTPS proxy client certificate.

Equivalent to --pass but used in HTTPS proxy context.

If --proxy-pass is provided several times, the last set value is used.

Example:

curl --proxy-pass secret --proxy-key here -x https://proxy https://example.com

See also -x, --proxy and --proxy-key.

--proxy-pinnedpubkey

(TLS) Use the specified public key file (or hashes) to verify the proxy. This can be a path to a file which contains a single public key in PEM or DER format, or any number of base64 encoded sha256 hashes preceded by 'sha256//' and separated by ';'.

When negotiating a TLS or SSL connection, the server sends a certificate indicating its identity. A public key is extracted from this certificate and if it does not exactly match the public key provided to this option, curl aborts the connection before sending or receiving any data.

Before curl 8.10.0 this option did not work due to a bug.

If --proxy-pinnedpubkey is provided several times, the last set value is used.

Examples:

curl --proxy-pinnedpubkey keyfile https://example.com curl --proxy-pinnedpubkey 'sha256//ce118b51897f4452dc' https://example.com

See also --pinnedpubkey and -x, --proxy.

--proxy-service-name

Set the service name for SPNEGO when doing proxy authentication.

If --proxy-service-name is provided several times, the last set value is used.

Example:

curl --proxy-service-name "shrubbery" -x proxy https://example.com

See also --service-name, -x, --proxy and --proxy-negotiate.

--proxy-ssl-allow-beast

Do not work around a security flaw in the TLS1.0 protocol known as BEAST when communicating to an HTTPS proxy. If this option is not used, the TLS layer may use workarounds known to cause interoperability problems with some older server implementations.

This option only changes how curl does TLS 1.0 with an HTTPS proxy and has no effect on later TLS versions.

WARNING: this option loosens the TLS security, and by using this flag you ask for exactly that.

Equivalent to --ssl-allow-beast but used in HTTPS proxy context.

Providing --proxy-ssl-allow-beast multiple times has no extra effect. Disable it again with --no-proxy-ssl-allow-beast.

Example:

curl --proxy-ssl-allow-beast -x https://proxy https://example.com

See also --ssl-allow-beast and -x, --proxy.

--proxy-ssl-auto-client-cert

Same as --ssl-auto-client-cert but used in HTTPS proxy context.

This is only supported by Schannel.

Providing --proxy-ssl-auto-client-cert multiple times has no extra effect. Disable it again with --no-proxy-ssl-auto-client-cert.

Example:

curl --proxy-ssl-auto-client-cert -x https://proxy https://example.com

Added in 7.77.0. See also --ssl-auto-client-cert and -x, --proxy.

--proxy-tls13-ciphers

(TLS) Same as --tls13-ciphers but used in HTTPS proxy context.

Specify which cipher suites to use in the connection to your HTTPS proxy when it negotiates TLS 1.3. The list of ciphers suites must specify valid ciphers. Read up on TLS 1.3 cipher suite details on this URL:

https://curl.se/docs/ssl-ciphers.html

This option is used when curl is built to use OpenSSL 1.1.1 or later, Schannel, wolfSSL, or mbedTLS 3.6.0 or later.

Before curl 8.10.0 with mbedTLS or wolfSSL, TLS 1.3 cipher suites were set by using the --proxy-ciphers option.

If --proxy-tls13-ciphers is provided several times, the last set value is used.

Example:

curl --proxy-tls13-ciphers TLS_AES_128_GCM_SHA256 -x proxy https://example.com

Added in 7.61.0. See also --proxy-ciphers, --tls13-ciphers and -x, --proxy.

--proxy-tlsauthtype

Set TLS authentication type with HTTPS proxy. The only supported option is "SRP", for TLS-SRP (RFC 5054). This option works only if the underlying libcurl is built with TLS-SRP support.

Equivalent to --tlsauthtype but used in HTTPS proxy context.

If --proxy-tlsauthtype is provided several times, the last set value is used.

Example:

curl --proxy-tlsauthtype SRP -x https://proxy https://example.com

See also -x, --proxy, --proxy-tlsuser and --proxy-tlspassword.

--proxy-tlspassword

Set password to use with the TLS authentication method specified with --proxy-tlsauthtype when using HTTPS proxy. Requires that --proxy-tlsuser is set.

This option does not work with TLS 1.3.

Equivalent to --tlspassword but used in HTTPS proxy context.

If --proxy-tlspassword is provided several times, the last set value is used.

Example:

curl --proxy-tlspassword passwd -x https://proxy https://example.com

See also -x, --proxy and --proxy-tlsuser.

--proxy-tlsuser

Set username for use for HTTPS proxy with the TLS authentication method specified with --proxy-tlsauthtype. Requires that --proxy-tlspassword also is set.

This option does not work with TLS 1.3.

If --proxy-tlsuser is provided several times, the last set value is used.

Example:

curl --proxy-tlsuser smith -x https://proxy https://example.com

See also -x, --proxy and --proxy-tlspassword.

--proxy-tlsv1

Use at least TLS version 1.x when negotiating with an HTTPS proxy. That means TLS version 1.0 or higher

Equivalent to -1, --tlsv1 but for an HTTPS proxy context.

Providing --proxy-tlsv1 multiple times has no extra effect.

Example:

curl --proxy-tlsv1 -x https://proxy https://example.com

See also -x, --proxy.

-U, --proxy-user user:password

Specify the username and password to use for proxy authentication.

If you use a Windows SSPI-enabled curl binary and do either Negotiate or NTLM authentication then you can tell curl to select the username and password from your environment by specifying a single colon with this option: "-U :".

On systems where it works, curl hides the given option argument from process listings. This is not enough to protect credentials from possibly getting seen by other users on the same system as they still are visible for a moment before cleared. Such sensitive data should be retrieved from a file instead or similar and never used in clear text in a command line.

If --proxy-user is provided several times, the last set value is used.

Example:

curl --proxy-user smith:secret -x proxy https://example.com

See also --proxy-pass.

--proxy1.0 <host[:port]>

Use the specified HTTP 1.0 proxy. If the port number is not specified, it is assumed at port 1080.

The only difference between this and the HTTP proxy option -x, --proxy, is that attempts to use CONNECT through the proxy specifies an HTTP 1.0 protocol instead of the default HTTP 1.1.

Providing --proxy1.0 multiple times has no extra effect.

Example:

curl --proxy1.0 http://proxy https://example.com

See also -x, --proxy, --socks5 and --preproxy.

-p, --proxytunnel

When an HTTP proxy is used -x, --proxy, this option makes curl tunnel the traffic through the proxy. The tunnel approach is made with the HTTP proxy CONNECT request and requires that the proxy allows direct connect to the remote port number curl wants to tunnel through to.

To suppress proxy CONNECT response headers when curl is set to output headers use --suppress-connect-headers.

Providing --proxytunnel multiple times has no extra effect. Disable it again with --no-proxytunnel.

Example:

curl --proxytunnel -x http://proxy https://example.com

See also -x, --proxy.

--pubkey

(SFTP SCP) Public key filename. Allows you to provide your public key in this separate file.

curl attempts to automatically extract the public key from the private key file, so passing this option is generally not required. Note that this public key extraction requires libcurl to be linked against a copy of libssh2 1.2.8 or higher that is itself linked against OpenSSL.

If --pubkey is provided several times, the last set value is used.

Example:

curl --pubkey file.pub sftp://example.com/

See also --pass.

-Q, --quote

(FTP SFTP) Send an arbitrary command to the remote FTP or SFTP server. Quote commands are sent BEFORE the transfer takes place (just after the initial PWD command in an FTP transfer, to be exact). To make commands take place after a successful transfer, prefix them with a dash '-'.

(FTP only) To make commands be sent after curl has changed the working directory, just before the file transfer command(s), prefix the command with a '+'. This is not performed when a directory listing is performed.

You may specify any number of commands.

By default curl stops at first failure. To make curl continue even if the command fails, prefix the command with an asterisk (*). Otherwise, if the server returns failure for one of the commands, the entire operation is aborted.

You must send syntactically correct FTP commands as RFC 959 defines to FTP servers, or one of the commands listed below to SFTP servers.

SFTP is a binary protocol. Unlike for FTP, curl interprets SFTP quote commands itself before sending them to the server. Filenames may be quoted shell-style to embed spaces or special characters. Following is the list of all supported SFTP quote commands:

atime date file

The atime command sets the last access time of the file named by the file operand. The date expression can be all sorts of date strings, see the curl_getdate(3) man page for date expression details. (Added in 7.73.0)

chgrp group file

The chgrp command sets the group ID of the file named by the file operand to the group ID specified by the group operand. The group operand is a decimal integer group ID.

chmod mode file

The chmod command modifies the file mode bits of the specified file. The mode operand is an octal integer mode number.

chown user file

The chown command sets the owner of the file named by the file operand to the user ID specified by the user operand. The user operand is a decimal integer user ID.

ln source_file target_file

The ln and symlink commands create a symbolic link at the target_file location pointing to the source_file location.

mkdir directory_name

The mkdir command creates the directory named by the directory_name operand.

mtime date file

The mtime command sets the last modification time of the file named by the file operand. The date expression can be all sorts of date strings, see the curl_getdate(3) man page for date expression details. (Added in 7.73.0)

pwd

The pwd command returns the absolute path name of the current working directory.

rename source target

The rename command renames the file or directory named by the source operand to the destination path named by the target operand.

rm file

The rm command removes the file specified by the file operand.

rmdir directory

The rmdir command removes the directory entry specified by the directory operand, provided it is empty.

symlink source_file target_file

See ln.

--quote can be used several times in a command line

Example:

curl --quote "DELE file" ftp://example.com/foo

See also -X, --request.

--random-file

Deprecated option. This option is ignored (added in 7.84.0). Prior to that it only had an effect on curl if built to use old versions of OpenSSL.

Specify the path name to file containing random data. The data may be used to seed the random engine for SSL connections.

If --random-file is provided several times, the last set value is used.

Example:

curl --random-file rubbish https://example.com

See also --egd-file.

-r, --range

(HTTP FTP SFTP FILE) Retrieve a byte range (i.e. a partial document) from an HTTP/1.1, FTP or SFTP server or a local FILE. Ranges can be specified in a number of ways.

0-499

specifies the first 500 bytes

500-999

specifies the second 500 bytes

-500

specifies the last 500 bytes

9500-

specifies the bytes from offset 9500 and forward

0-0,-1

specifies the first and last byte only(*)(HTTP)

100-199,500-599

specifies two separate 100-byte ranges(*) (HTTP)

(*) = NOTE that these make the server reply with a multipart response, which is returned as-is by curl. Parsing or otherwise transforming this response is the responsibility of the caller.

Only digit characters (0-9) are valid in the 'start' and 'stop' fields of the 'start-stop' range syntax. If a non-digit character is given in the range, the server's response is unspecified, depending on the server's configuration.

Many HTTP/1.1 servers do not have this feature enabled, so that when you attempt to get a range, curl instead gets the whole document.

FTP and SFTP range downloads only support the simple 'start-stop' syntax (optionally with one of the numbers omitted). FTP use depends on the extended FTP command SIZE.

If --range is provided several times, the last set value is used.

Example:

curl --range 22-44 https://example.com

See also -C, --continue-at and -a, --append.

--rate

Specify the maximum transfer frequency you allow curl to use - in number of transfer starts per time unit (sometimes called request rate). Without this option, curl starts the next transfer as fast as possible.

If given several URLs and a transfer completes faster than the allowed rate, curl waits until the next transfer is started to maintain the requested rate. This option has no effect when -Z, --parallel is used.

The request rate is provided as "N/U" where N is an integer number and U is a time unit. Supported units are 's' (second), 'm' (minute), 'h' (hour) and 'd' /(day, as in a 24 hour unit). The default time unit, if no "/U" is provided, is number of transfers per hour.

If curl is told to allow 10 requests per minute, it does not start the next request until 6 seconds have elapsed since the previous transfer was started.

This function uses millisecond resolution. If the allowed frequency is set more than 1000 per second, it instead runs unrestricted.

When retrying transfers, enabled with --retry, the separate retry delay logic is used and not this setting.

Starting in version 8.10.0, you can specify number of time units in the rate expression. Make curl do no more than 5 transfers per 15 seconds with "5/15s" or limit it to 3 transfers per 4 hours with "3/4h". No spaces allowed.

This option is global and does not need to be specified for each use of --next.

If --rate is provided several times, the last set value is used.

Examples:

curl --rate 2/s https://example.com ... curl --rate 3/h https://example.com ... curl --rate 14/m https://example.com ...

Added in 7.84.0. See also --limit-rate and --retry-delay.

--raw

(HTTP) When used, it disables all internal HTTP decoding of content or transfer encodings and instead makes them passed on unaltered, raw.

Providing --raw multiple times has no extra effect. Disable it again with --no-raw.

Example:

curl --raw https://example.com

See also --tr-encoding.

-e, --referer

(HTTP) Set the referrer URL in the HTTP request. This can also be set with the -H, --header flag of course. When used with -L, --location you can append ";auto"" to the -e, --referer URL to make curl automatically set the previous URL when it follows a Location: header. The ";auto" string can be used alone, even if you do not set an initial -e, --referer.

If --referer is provided several times, the last set value is used.

Examples:

curl --referer "https://fake.example" https://example.com curl --referer "https://fake.example;auto" -L https://example.com curl --referer ";auto" -L https://example.com

See also -A, --user-agent and -H, --header.

-J, --remote-header-name

(HTTP) Tell the -O, --remote-name option to use the server-specified Content-Disposition filename instead of extracting a filename from the URL. If the server-provided filename contains a path, that is stripped off before the filename is used.

The file is saved in the current directory, or in the directory specified with --output-dir.

If the server specifies a filename and a file with that name already exists in the destination directory, it is not overwritten and an error occurs - unless you allow it by using the --clobber option. If the server does not specify a filename then this option has no effect.

There is no attempt to decode %-sequences (yet) in the provided filename, so this option may provide you with rather unexpected filenames.

This feature uses the name from the "filename" field, it does not yet support the "filename*" field (filenames with explicit character sets).

WARNING: Exercise judicious use of this option, especially on Windows. A rogue server could send you the name of a DLL or other file that could be loaded automatically by Windows or some third party software.

Providing --remote-header-name multiple times has no extra effect. Disable it again with --no-remote-header-name.

Example:

curl -OJ https://example.com/file

See also -O, --remote-name.

-O, --remote-name

Write output to a local file named like the remote file we get. (Only the file part of the remote file is used, the path is cut off.)

The file is saved in the current working directory. If you want the file saved in a different directory, make sure you change the current working directory before invoking curl with this option or use --output-dir.

The remote filename to use for saving is extracted from the given URL, nothing else, and if it already exists it is overwritten. If you want the server to be able to choose the filename refer to -J, --remote-header-name which can be used in addition to this option. If the server chooses a filename and that name already exists it is not overwritten.

There is no URL decoding done on the filename. If it has %20 or other URL encoded parts of the name, they end up as-is as filename.

You may use this option as many times as the number of URLs you have.

Before curl 8.10.0, curl returned an error if the URL ended with a slash, which means that there is no filename part in the URL. Starting in 8.10.0, curl sets the filename to the last directory part of the URL or if that also is missing to "curl_response" (without extension) for this situation.

--remote-name is associated with a single URL. Use it once per URL when you use several URLs in a command line.

Examples:

curl -O https://example.com/filename curl -O https://example.com/filename -O https://example.com/file2

See also --remote-name-all, --output-dir and -J, --remote-header-name.

--remote-name-all

Change the default action for all given URLs to be dealt with as if -O, --remote-name were used for each one. If you want to disable that for a specific URL after --remote-name-all has been used, you must use "-o -" or --no-remote-name.

Providing --remote-name-all multiple times has no extra effect. Disable it again with --no-remote-name-all.

Example:

curl --remote-name-all ftp://example.com/file1 ftp://example.com/file2

See also -O, --remote-name.

-R, --remote-time

Makes curl attempt to figure out the timestamp of the remote file that is getting downloaded, and if that is available make the local file get that same timestamp.

Providing --remote-time multiple times has no extra effect. Disable it again with --no-remote-time.

Example:

curl --remote-time -o foo https://example.com

See also -O, --remote-name and -z, --time-cond.

--remove-on-error

Remove output file if an error occurs. If curl returns an error when told to save output in a local file. This prevents curl from leaving a partial file in the case of an error during transfer.

If the output is not a regular file, this option has no effect.

Providing --remove-on-error multiple times has no extra effect. Disable it again with --no-remove-on-error.

Example:

curl --remove-on-error -o output https://example.com

Added in 7.83.0. See also -f, --fail.

-X, --request

Change the method to use when starting the transfer.

curl passes on the verbatim string you give it in the request without any filter or other safe guards. That includes white space and control characters.

HTTP

Specifies a custom request method to use when communicating with the HTTP server. The specified request method is used instead of the method otherwise used (which defaults to GET). Read the HTTP 1.1 specification for details and explanations. Common additional HTTP requests include PUT and DELETE, while related technologies like WebDAV offers PROPFIND, COPY, MOVE and more.

Normally you do not need this option. All sorts of GET, HEAD, POST and PUT requests are rather invoked by using dedicated command line options.

This option only changes the actual word used in the HTTP request, it does not alter the way curl behaves. For example if you want to make a proper HEAD request, using -X HEAD does not suffice. You need to use the -I, --head option.

The method string you set with -X, --request is used for all requests, which if you for example use -L, --location may cause unintended side-effects when curl does not change request method according to the HTTP 30x response codes - and similar.

FTP

Specifies a custom FTP command to use instead of LIST when doing file lists with FTP.

POP3

Specifies a custom POP3 command to use instead of LIST or RETR.

IMAP

Specifies a custom IMAP command to use instead of LIST.

SMTP

Specifies a custom SMTP command to use instead of HELP or VRFY.

If --request is provided several times, the last set value is used.

Examples:

curl -X "DELETE" https://example.com curl -X NLST ftp://example.com/

See also --request-target.

--request-target

(HTTP) Use an alternative target (path) instead of using the path as provided in the URL. Particularly useful when wanting to issue HTTP requests without leading slash or other data that does not follow the regular URL pattern, like "OPTIONS *".

curl passes on the verbatim string you give it its the request without any filter or other safe guards. That includes white space and control characters.

If --request-target is provided several times, the last set value is used.

Example:

curl --request-target "*" -X OPTIONS https://example.com

See also -X, --request.

--resolve <[+]host:port:addr[,addr]...>

Provide a custom address for a specific host and port pair. Using this, you can make the curl requests(s) use a specified address and prevent the otherwise normally resolved address to be used. Consider it a sort of /etc/hosts alternative provided on the command line. The port number should be the number used for the specific protocol the host is used for. It means you need several entries if you want to provide address for the same host but different ports.

By specifying "*" as host you can tell curl to resolve any host and specific port pair to the specified address. Wildcard is resolved last so any --resolve with a specific host and port is used first.

The provided address set by this option is used even if -4, --ipv4 or -6, --ipv6 is set to make curl use another IP version.

By prefixing the host with a '+' you can make the entry time out after curl's default timeout (1 minute). Note that this only makes sense for long running parallel transfers with a lot of files. In such cases, if this option is used curl tries to resolve the host as it normally would once the timeout has expired.

To redirect connects from a specific hostname or any hostname, independently of port number, consider the --connect-to option.

Support for resolving with wildcard was added in 7.64.0.

Support for the '+' prefix was added in 7.75.0.

--resolve can be used several times in a command line

Example:

curl --resolve example.com:443:127.0.0.1 https://example.com

See also --connect-to and --alt-svc.

--retry

If a transient error is returned when curl tries to perform a transfer, it retries this number of times before giving up. Setting the number to 0 makes curl do no retries (which is the default). Transient error means either: a timeout, an FTP 4xx response code or an HTTP 408, 429, 500, 502, 503 or 504 response code.

When curl is about to retry a transfer, it first waits one second and then for all forthcoming retries it doubles the waiting time until it reaches 10 minutes which then remains delay between the rest of the retries. By using --retry-delay you disable this exponential backoff algorithm. See also --retry-max-time to limit the total time allowed for retries.

curl complies with the Retry-After: response header if one was present to know when to issue the next retry (added in 7.66.0).

If --retry is provided several times, the last set value is used.

Example:

curl --retry 7 https://example.com

See also --retry-max-time.

--retry-all-errors

Retry on any error. This option is used together with --retry.

This option is the "sledgehammer" of retrying. Do not use this option by default (for example in your curlrc), there may be unintended consequences such as sending or receiving duplicate data. Do not use with redirected input or output. You might be better off handling your unique problems in a shell script. Please read the example below.

WARNING: For server compatibility curl attempts to retry failed flaky transfers as close as possible to how they were started, but this is not possible with redirected input or output. For example, before retrying it removes output data from a failed partial transfer that was written to an output file. However this is not true of data redirected to a | pipe or > file, which are not reset. We strongly suggest you do not parse or record output via redirect in combination with this option, since you may receive duplicate data.

By default curl does not return error for transfers with an HTTP response code that indicates an HTTP error, if the transfer was successful. For example, if a server replies 404 Not Found and the reply is fully received then that is not an error. When --retry is used then curl retries on some HTTP response codes that indicate transient HTTP errors, but that does not include most 4xx response codes such as 404. If you want to retry on all response codes that indicate HTTP errors (4xx and 5xx) then combine with -f, --fail.

Providing --retry-all-errors multiple times has no extra effect. Disable it again with --no-retry-all-errors.

Example:

curl --retry 5 --retry-all-errors https://example.com

Added in 7.71.0. See also --retry.

--retry-connrefused

In addition to the other conditions, consider ECONNREFUSED as a transient error too for --retry. This option is used together with --retry.

Providing --retry-connrefused multiple times has no extra effect. Disable it again with --no-retry-connrefused.

Example:

curl --retry-connrefused --retry 7 https://example.com

See also --retry and --retry-all-errors.

--retry-delay

Make curl sleep this amount of time before each retry when a transfer has failed with a transient error (it changes the default backoff time algorithm between retries). This option is only interesting if --retry is also used. Setting this delay to zero makes curl use the default backoff time.

If --retry-delay is provided several times, the last set value is used.

Example:

curl --retry-delay 5 --retry 7 https://example.com

See also --retry.

--retry-max-time

The retry timer is reset before the first transfer attempt. Retries are done as usual (see --retry) as long as the timer has not reached this given limit. Notice that if the timer has not reached the limit, the request is made and while performing, it may take longer than this given time period. To limit a single request's maximum time, use -m, --max-time. Set this option to zero to not timeout retries.

If --retry-max-time is provided several times, the last set value is used.

Example:

curl --retry-max-time 30 --retry 10 https://example.com

See also --retry.

--sasl-authzid

Use this authorization identity (authzid), during SASL PLAIN authentication, in addition to the authentication identity (authcid) as specified by -u, --user.

If the option is not specified, the server derives the authzid from the authcid, but if specified, and depending on the server implementation, it may be used to access another user's inbox, that the user has been granted access to, or a shared mailbox for example.

If --sasl-authzid is provided several times, the last set value is used.

Example:

curl --sasl-authzid zid imap://example.com/

Added in 7.66.0. See also --login-options.

--sasl-ir

Enable initial response in SASL authentication.

Providing --sasl-ir multiple times has no extra effect. Disable it again with --no-sasl-ir.

Example:

curl --sasl-ir imap://example.com/

See also --sasl-authzid.

--service-name

Set the service name for SPNEGO.

If --service-name is provided several times, the last set value is used.

Example:

curl --service-name sockd/server https://example.com

See also --negotiate and --proxy-service-name.

-S, --show-error

When used with -s, --silent, it makes curl show an error message if it fails.

This option is global and does not need to be specified for each use of --next.

Providing --show-error multiple times has no extra effect. Disable it again with --no-show-error.

Example:

curl --show-error --silent https://example.com

See also --no-progress-meter.

-i, --show-headers

(HTTP FTP) Show response headers in the output. HTTP response headers can include things like server name, cookies, date of the document, HTTP version and more. With non-HTTP protocols, the "headers" are other server communication.

This option makes the response headers get saved in the same stream/output as the data. -D, --dump-header exists to save headers in a separate stream.

To view the request headers, consider the -v, --verbose option.

Prior to 7.75.0 curl did not print the headers if -f, --fail was used in combination with this option and there was error reported by server.

This option was called --include before 8.10.0. The previous name remains functional.

Providing --show-headers multiple times has no extra effect. Disable it again with --no-show-headers.

Example:

curl -i https://example.com

See also -v, --verbose and -D, --dump-header.

-s, --silent

Silent or quiet mode. Do not show progress meter or error messages. Makes Curl mute. It still outputs the data you ask for, potentially even to the terminal/stdout unless you redirect it.

Use -S, --show-error in addition to this option to disable progress meter but still show error messages.

Providing --silent multiple times has no extra effect. Disable it again with --no-silent.

Example:

curl -s https://example.com

See also -v, --verbose, --stderr and --no-progress-meter.

--skip-existing

If there is a local file present when a download is requested, the operation is skipped. Note that curl cannot know if the local file was previously downloaded fine, or if it is incomplete etc, it just knows if there is a filename present in the file system or not and it skips the transfer if it is.

Providing --skip-existing multiple times has no extra effect. Disable it again with --no-skip-existing.

Example:

curl --skip-existing --output local/dir/file https://example.com

Added in 8.10.0. See also -o, --output, -O, --remote-name and --no-clobber.

--socks4 <host[:port]>

Use the specified SOCKS4 proxy. If the port number is not specified, it is assumed at port 1080. Using this socket type make curl resolve the hostname and passing the address on to the proxy.

To specify proxy on a Unix domain socket, use localhost for host, e.g. "socks4://localhost/path/to/socket.sock"

This option overrides any previous use of -x, --proxy, as they are mutually exclusive.

This option is superfluous since you can specify a socks4 proxy with -x, --proxy using a socks4:// protocol prefix.

--preproxy can be used to specify a SOCKS proxy at the same time proxy is used with an HTTP/HTTPS proxy. In such a case, curl first connects to the SOCKS proxy and then connects (through SOCKS) to the HTTP or HTTPS proxy.

If --socks4 is provided several times, the last set value is used.

Example:

curl --socks4 hostname:4096 https://example.com

See also --socks4a, --socks5 and --socks5-hostname.

--socks4a <host[:port]>

Use the specified SOCKS4a proxy. If the port number is not specified, it is assumed at port 1080. This asks the proxy to resolve the hostname.

To specify proxy on a Unix domain socket, use localhost for host, e.g. "socks4a://localhost/path/to/socket.sock"

This option overrides any previous use of -x, --proxy, as they are mutually exclusive.

This option is superfluous since you can specify a socks4a proxy with -x, --proxy using a socks4a:// protocol prefix.

--preproxy can be used to specify a SOCKS proxy at the same time -x, --proxy is used with an HTTP/HTTPS proxy. In such a case, curl first connects to the SOCKS proxy and then connects (through SOCKS) to the HTTP or HTTPS proxy.

If --socks4a is provided several times, the last set value is used.

Example:

curl --socks4a hostname:4096 https://example.com

See also --socks4, --socks5 and --socks5-hostname.

--socks5 <host[:port]>

Use the specified SOCKS5 proxy - but resolve the hostname locally. If the port number is not specified, it is assumed at port 1080.

To specify proxy on a Unix domain socket, use localhost for host, e.g. "socks5://localhost/path/to/socket.sock"

This option overrides any previous use of -x, --proxy, as they are mutually exclusive.

This option is superfluous since you can specify a socks5 proxy with -x, --proxy using a socks5:// protocol prefix.

--preproxy can be used to specify a SOCKS proxy at the same time -x, --proxy is used with an HTTP/HTTPS proxy. In such a case, curl first connects to the SOCKS proxy and then connects (through SOCKS) to the HTTP or HTTPS proxy.

This option does not work with FTPS or LDAP.

If --socks5 is provided several times, the last set value is used.

Example:

curl --socks5 proxy.example:7000 https://example.com

See also --socks5-hostname and --socks4a.

--socks5-basic

Use username/password authentication when connecting to a SOCKS5 proxy. The username/password authentication is enabled by default. Use --socks5-gssapi to force GSS-API authentication to SOCKS5 proxies.

Providing --socks5-basic multiple times has no extra effect.

Example:

curl --socks5-basic --socks5 hostname:4096 https://example.com

See also --socks5.

--socks5-gssapi

Use GSS-API authentication when connecting to a SOCKS5 proxy. The GSS-API authentication is enabled by default (if curl is compiled with GSS-API support). Use --socks5-basic to force username/password authentication to SOCKS5 proxies.

Providing --socks5-gssapi multiple times has no extra effect. Disable it again with --no-socks5-gssapi.

Example:

curl --socks5-gssapi --socks5 hostname:4096 https://example.com

See also --socks5.

--socks5-gssapi-nec

As part of the GSS-API negotiation a protection mode is negotiated. RFC 1961 says in section 4.3/4.4 it should be protected, but the NEC reference implementation does not. The option --socks5-gssapi-nec allows the unprotected exchange of the protection mode negotiation.

Providing --socks5-gssapi-nec multiple times has no extra effect. Disable it again with --no-socks5-gssapi-nec.

Example:

curl --socks5-gssapi-nec --socks5 hostname:4096 https://example.com

See also --socks5.

--socks5-gssapi-service

Set the service name for a socks server. Default is rcmd/server-fqdn.

If --socks5-gssapi-service is provided several times, the last set value is used.

Example:

curl --socks5-gssapi-service sockd --socks5 hostname:4096 https://example.com

See also --socks5.

--socks5-hostname <host[:port]>

Use the specified SOCKS5 proxy (and let the proxy resolve the hostname). If the port number is not specified, it is assumed at port 1080.

To specify proxy on a Unix domain socket, use localhost for host, e.g. "socks5h://localhost/path/to/socket.sock"

This option overrides any previous use of -x, --proxy, as they are mutually exclusive.

This option is superfluous since you can specify a socks5 hostname proxy with -x, --proxy using a socks5h:// protocol prefix.

--preproxy can be used to specify a SOCKS proxy at the same time -x, --proxy is used with an HTTP/HTTPS proxy. In such a case, curl first connects to the SOCKS proxy and then connects (through SOCKS) to the HTTP or HTTPS proxy.

If --socks5-hostname is provided several times, the last set value is used.

Example:

curl --socks5-hostname proxy.example:7000 https://example.com

See also --socks5 and --socks4a.

-Y, --speed-limit

If a transfer is slower than this set speed (in bytes per second) for a given number of seconds, it gets aborted. The time period is set with -y, --speed-time and is 30 seconds by default.

If --speed-limit is provided several times, the last set value is used.

Example:

curl --speed-limit 300 --speed-time 10 https://example.com

See also -y, --speed-time, --limit-rate and -m, --max-time.

-y, --speed-time

If a transfer runs slower than speed-limit bytes per second during a speed-time period, the transfer is aborted. If speed-time is used, the default speed-limit is 1 unless set with -Y, --speed-limit.

This option controls transfers (in both directions) but does not affect slow connects etc. If this is a concern for you, try the --connect-timeout option.

If --speed-time is provided several times, the last set value is used.

Example:

curl --speed-limit 300 --speed-time 10 https://example.com

See also -Y, --speed-limit and --limit-rate.

--ssl

(FTP IMAP POP3 SMTP LDAP) Warning: this is considered an insecure option. Consider using --ssl-reqd instead to be sure curl upgrades to a secure connection.

Try to use SSL/TLS for the connection - often referred to as STARTTLS or STLS because of the involved commands. Reverts to a non-secure connection if the server does not support SSL/TLS. See also --ftp-ssl-control and --ssl-reqd for different levels of encryption required.

This option is handled in LDAP (added in 7.81.0). It is fully supported by the OpenLDAP backend and ignored by the generic ldap backend.

Please note that a server may close the connection if the negotiation does not succeed.

This option was formerly known as --ftp-ssl. That option name can still be used but might be removed in a future version.

Providing --ssl multiple times has no extra effect. Disable it again with --no-ssl.

Example:

curl --ssl pop3://example.com/

See also --ssl-reqd, -k, --insecure and --ciphers.

--ssl-allow-beast

(TLS) Do not work around a security flaw in the TLS1.0 protocol known as BEAST. If this option is not used, the TLS layer may use workarounds known to cause interoperability problems with some older server implementations.

This option only changes how curl does TLS 1.0 and has no effect on later TLS versions.

WARNING: this option loosens the TLS security, and by using this flag you ask for exactly that.

Providing --ssl-allow-beast multiple times has no extra effect. Disable it again with --no-ssl-allow-beast.

Example:

curl --ssl-allow-beast https://example.com

See also --proxy-ssl-allow-beast and -k, --insecure.

--ssl-auto-client-cert

(TLS) (Schannel) Automatically locate and use a client certificate for authentication, when requested by the server. Since the server can request any certificate that supports client authentication in the OS certificate store it could be a privacy violation and unexpected.

Providing --ssl-auto-client-cert multiple times has no extra effect. Disable it again with --no-ssl-auto-client-cert.

Example:

curl --ssl-auto-client-cert https://example.com

Added in 7.77.0. See also --proxy-ssl-auto-client-cert.

--ssl-no-revoke

(TLS) (Schannel) Disable certificate revocation checks. WARNING: this option loosens the SSL security, and by using this flag you ask for exactly that.

Providing --ssl-no-revoke multiple times has no extra effect. Disable it again with --no-ssl-no-revoke.

Example:

curl --ssl-no-revoke https://example.com

See also --crlfile.

--ssl-reqd

(FTP IMAP POP3 SMTP LDAP) Require SSL/TLS for the connection - often referred to as STARTTLS or STLS because of the involved commands. Terminates the connection if the transfer cannot be upgraded to use SSL/TLS.

This option is handled in LDAP (added in 7.81.0). It is fully supported by the OpenLDAP backend and rejected by the generic ldap backend if explicit TLS is required.

This option is unnecessary if you use a URL scheme that in itself implies immediate and implicit use of TLS, like for FTPS, IMAPS, POP3S, SMTPS and LDAPS. Such a transfer always fails if the TLS handshake does not work.

This option was formerly known as --ftp-ssl-reqd.

Providing --ssl-reqd multiple times has no extra effect. Disable it again with --no-ssl-reqd.

Example:

curl --ssl-reqd ftp://example.com

See also --ssl and -k, --insecure.

--ssl-revoke-best-effort

(TLS) (Schannel) Ignore certificate revocation checks when they failed due to missing/offline distribution points for the revocation check lists.

Providing --ssl-revoke-best-effort multiple times has no extra effect. Disable it again with --no-ssl-revoke-best-effort.

Example:

curl --ssl-revoke-best-effort https://example.com

Added in 7.70.0. See also --crlfile and -k, --insecure.

-2, --sslv2

(SSL) This option previously asked curl to use SSLv2, but is now ignored (added in 7.77.0). SSLv2 is widely considered insecure (see RFC 6176).

Providing --sslv2 multiple times has no extra effect.

Example:

curl --sslv2 https://example.com

-2, --sslv2 requires that libcurl is built to support TLS. This option is mutually exclusive with -3, --sslv3, -1, --tlsv1, --tlsv1.1 and --tlsv1.2. See also --http1.1 and --http2.

-3, --sslv3

(SSL) This option previously asked curl to use SSLv3, but is now ignored (added in 7.77.0). SSLv3 is widely considered insecure (see RFC 7568).

Providing --sslv3 multiple times has no extra effect.

Example:

curl --sslv3 https://example.com

-3, --sslv3 requires that libcurl is built to support TLS. This option is mutually exclusive with -2, --sslv2, -1, --tlsv1, --tlsv1.1 and --tlsv1.2. See also --http1.1 and --http2.

--stderr

Redirect all writes to stderr to the specified file instead. If the filename is a plain '-', it is instead written to stdout.

This option is global and does not need to be specified for each use of --next.

If --stderr is provided several times, the last set value is used.

Example:

curl --stderr output.txt https://example.com

See also -v, --verbose and -s, --silent.

--styled-output

Enable automatic use of bold font styles when writing HTTP headers to the terminal. Use --no-styled-output to switch them off.

Styled output requires a terminal that supports bold fonts. This feature is not present on curl for Windows due to lack of this capability.

This option is global and does not need to be specified for each use of --next.

Providing --styled-output multiple times has no extra effect. Disable it again with --no-styled-output.

Example:

curl --styled-output -I https://example.com

Added in 7.61.0. See also -I, --head and -v, --verbose.

--suppress-connect-headers

When -p, --proxytunnel is used and a CONNECT request is made do not output proxy CONNECT response headers. This option is meant to be used with -D, --dump-header or -i, --show-headers which are used to show protocol headers in the output. It has no effect on debug options such as -v, --verbose or --trace, or any statistics.

Providing --suppress-connect-headers multiple times has no extra effect. Disable it again with --no-suppress-connect-headers.

Example:

curl --suppress-connect-headers --show-headers -x proxy https://example.com

See also -D, --dump-header, -i, --show-headers and -p, --proxytunnel.

--tcp-fastopen

Enable use of TCP Fast Open (RFC 7413). TCP Fast Open is a TCP extension that allows data to get sent earlier over the connection (before the final handshake ACK) if the client and server have been connected previously.

Providing --tcp-fastopen multiple times has no extra effect. Disable it again with --no-tcp-fastopen.

Example:

curl --tcp-fastopen https://example.com

See also --false-start.

--tcp-nodelay

Turn on the TCP_NODELAY option. See the curl_easy_setopt(3) man page for details about this option.

curl sets this option by default and you need to explicitly switch it off if you do not want it on.

Providing --tcp-nodelay multiple times has no extra effect. Disable it again with --no-tcp-nodelay.

Example:

curl --tcp-nodelay https://example.com

See also -N, --no-buffer.

-t, --telnet-option <opt=val>

Pass options to the telnet protocol. Supported options are:

TTYPE=

Sets the terminal type.

XDISPLOC=

Sets the X display location.

NEW_ENV=<var,val>

Sets an environment variable.

--telnet-option can be used several times in a command line

Example:

curl -t TTYPE=vt100 telnet://example.com/

See also -K, --config.

--tftp-blksize

(TFTP) Set the TFTP BLKSIZE option (must be 512 or larger). This is the block size that curl tries to use when transferring data to or from a TFTP server. By default 512 bytes are used.

If --tftp-blksize is provided several times, the last set value is used.

Example:

curl --tftp-blksize 1024 tftp://example.com/file

See also --tftp-no-options.

--tftp-no-options

(TFTP) Do not to send TFTP options requests. This improves interop with some legacy servers that do not acknowledge or properly implement TFTP options. When this option is used --tftp-blksize is ignored.

Providing --tftp-no-options multiple times has no extra effect. Disable it again with --no-tftp-no-options.

Example:

curl --tftp-no-options tftp://192.168.0.1/

See also --tftp-blksize.

-z, --time-cond

(HTTP FTP) Request a file that has been modified later than the given time and date, or one that has been modified before that time. The date expression can be all sorts of date strings or if it does not match any internal ones, it is treated as a filename and curl tries to get the modification date (mtime) from that file instead. See the curl_getdate(3) man pages for date expression details.

Start the date expression with a dash (-) to make it request for a document that is older than the given date/time, default is a document that is newer than the specified date/time.

If provided a non-existing file, curl outputs a warning about that fact and proceeds to do the transfer without a time condition.

If --time-cond is provided several times, the last set value is used.

Examples:

curl -z "Wed 01 Sep 2021 12🔞00" https://example.com curl -z "-Wed 01 Sep 2021 12🔞00" https://example.com curl -z file https://example.com

See also --etag-compare and -R, --remote-time.

--tls-earlydata

(TLS) Enable the use of TLSv1.3 early data, also known as '0RTT' where possible. This has security implications for the requests sent that way.

This option is used when curl is built to use GnuTLS.

If a server supports this TLSv1.3 feature, and to what extent, is announced as part of the TLS "session" sent back to curl. Until curl has seen such a session in a previous request, early data cannot be used.

When a new connection is initiated with a known TLSv1.3 session, and that session announced early data support, the first request on this connection is sent before the TLS handshake is complete. While the early data is also encrypted, it is not protected against replays. An attacker can send your early data to the server again and the server would accept it.

If your request contacts a public server and only retrieves a file, there may be no harm in that. If the first request orders a refrigerator for you, it is probably not a good idea to use early data for it. curl cannot deduce what the security implications of your requests actually are and make this decision for you.

WARNING: this option has security implications. See above for more details.

Providing --tls-earlydata multiple times has no extra effect. Disable it again with --no-tls-earlydata.

Example:

curl --tls-earlydata https://example.com

Added in 8.11.0. See also --tlsv1.3 and --tls-max.

--tls-max

(TLS) VERSION defines maximum supported TLS version. The minimum acceptable version is set by tlsv1.0, tlsv1.1, tlsv1.2 or tlsv1.3.

If the connection is done without TLS, this option has no effect. This includes QUIC-using (HTTP/3) transfers.

default

Use up to recommended TLS version.

1.0

Use up to TLSv1.0.

1.1

Use up to TLSv1.1.

1.2

Use up to TLSv1.2.

1.3

Use up to TLSv1.3.

If --tls-max is provided several times, the last set value is used.

Examples:

curl --tls-max 1.2 https://example.com curl --tls-max 1.3 --tlsv1.2 https://example.com

--tls-max requires that libcurl is built to support TLS. See also --tlsv1.0, --tlsv1.1, --tlsv1.2 and --tlsv1.3.

--tls13-ciphers

(TLS) Specifies which cipher suites to use in the connection if it negotiates TLS 1.3. The list of ciphers suites must specify valid ciphers. Read up on TLS 1.3 cipher suite details on this URL:

https://curl.se/docs/ssl-ciphers.html

This option is used when curl is built to use OpenSSL 1.1.1 or later, Schannel, wolfSSL, or mbedTLS 3.6.0 or later.

Before curl 8.10.0 with mbedTLS or wolfSSL, TLS 1.3 cipher suites were set by using the --ciphers option.

If --tls13-ciphers is provided several times, the last set value is used.

Example:

curl --tls13-ciphers TLS_AES_128_GCM_SHA256 https://example.com

Added in 7.61.0. See also --ciphers, --proxy-tls13-ciphers and --curves.

--tlsauthtype

(TLS) Set TLS authentication type. Currently, the only supported option is "SRP", for TLS-SRP (RFC 5054). If --tlsuser and --tlspassword are specified but --tlsauthtype is not, then this option defaults to "SRP". This option works only if the underlying libcurl is built with TLS-SRP support, which requires OpenSSL or GnuTLS with TLS-SRP support.

If --tlsauthtype is provided several times, the last set value is used.

Example:

curl --tlsauthtype SRP https://example.com

See also --tlsuser.

--tlspassword

(TLS) Set password to use with the TLS authentication method specified with --tlsauthtype. Requires that --tlsuser is set.

This option does not work with TLS 1.3.

If --tlspassword is provided several times, the last set value is used.

Example:

curl --tlspassword pwd --tlsuser user https://example.com

See also --tlsuser.

--tlsuser

(TLS) Set username for use with the TLS authentication method specified with --tlsauthtype. Requires that --tlspassword also is set.

This option does not work with TLS 1.3.

If --tlsuser is provided several times, the last set value is used.

Example:

curl --tlspassword pwd --tlsuser user https://example.com

See also --tlspassword.

-1, --tlsv1

(TLS) Use at least TLS version 1.x when negotiating with a remote TLS server. That means TLS version 1.0 or higher

Providing --tlsv1 multiple times has no extra effect.

Example:

curl --tlsv1 https://example.com

-1, --tlsv1 requires that libcurl is built to support TLS. This option is mutually exclusive with --tlsv1.1, --tlsv1.2 and --tlsv1.3. See also --http1.1 and --http2.

--tlsv1.0

(TLS) Forces curl to use TLS version 1.0 or later when connecting to a remote TLS server.

In old versions of curl this option was documented to allow _only_ TLS 1.0. That behavior was inconsistent depending on the TLS library. Use --tls-max if you want to set a maximum TLS version.

Providing --tlsv1.0 multiple times has no extra effect.

Example:

curl --tlsv1.0 https://example.com

See also --tlsv1.3.

--tlsv1.1

(TLS) Forces curl to use TLS version 1.1 or later when connecting to a remote TLS server.

In old versions of curl this option was documented to allow _only_ TLS 1.1. That behavior was inconsistent depending on the TLS library. Use --tls-max if you want to set a maximum TLS version.

Providing --tlsv1.1 multiple times has no extra effect.

Example:

curl --tlsv1.1 https://example.com

See also --tlsv1.3 and --tls-max.

--tlsv1.2

(TLS) Forces curl to use TLS version 1.2 or later when connecting to a remote TLS server.

In old versions of curl this option was documented to allow _only_ TLS 1.2. That behavior was inconsistent depending on the TLS library. Use --tls-max if you want to set a maximum TLS version.

Providing --tlsv1.2 multiple times has no extra effect.

Example:

curl --tlsv1.2 https://example.com

See also --tlsv1.3 and --tls-max.

--tlsv1.3

(TLS) Forces curl to use TLS version 1.3 or later when connecting to a remote TLS server.

If the connection is done without TLS, this option has no effect. This includes QUIC-using (HTTP/3) transfers.

Note that TLS 1.3 is not supported by all TLS backends.

Providing --tlsv1.3 multiple times has no extra effect.

Example:

curl --tlsv1.3 https://example.com

See also --tlsv1.2 and --tls-max.

--tr-encoding

(HTTP) Request a compressed Transfer-Encoding response using one of the algorithms curl supports, and uncompress the data while receiving it.

Providing --tr-encoding multiple times has no extra effect. Disable it again with --no-tr-encoding.

Example:

curl --tr-encoding https://example.com

See also --compressed.

--trace

Save a full trace dump of all incoming and outgoing data, including descriptive information, in the given output file. Use "-" as filename to have the output sent to stdout. Use "%" as filename to have the output sent to stderr.

Note that verbose output of curl activities and network traffic might contain sensitive data, including usernames, credentials or secret data content. Be aware and be careful when sharing trace logs with others.

This option is global and does not need to be specified for each use of --next.

If --trace is provided several times, the last set value is used.

Example:

curl --trace log.txt https://example.com

This option is mutually exclusive with -v, --verbose and --trace-ascii. See also --trace-ascii, --trace-config, --trace-ids and --trace-time.

--trace-ascii

Save a full trace dump of all incoming and outgoing data, including descriptive information, in the given output file. Use "-" as filename to have the output sent to stdout. Use "%" as filename to send the output to stderr.

This is similar to --trace, but leaves out the hex part and only shows the ASCII part of the dump. It makes smaller output that might be easier to read for untrained humans.

Note that verbose output of curl activities and network traffic might contain sensitive data, including usernames, credentials or secret data content. Be aware and be careful when sharing trace logs with others.

This option is global and does not need to be specified for each use of --next.

If --trace-ascii is provided several times, the last set value is used.

Example:

curl --trace-ascii log.txt https://example.com

This option is mutually exclusive with --trace and -v, --verbose. See also -v, --verbose and --trace.

--trace-config

Set configuration for trace output. A comma-separated list of components where detailed output can be made available from. Names are case-insensitive. Specify 'all' to enable all trace components.

In addition to trace component names, specify "ids" and "time" to avoid extra --trace-ids or --trace-time parameters.

See the curl_global_trace(3) man page for more details.

This option is global and does not need to be specified for each use of --next.

--trace-config can be used several times in a command line

Example:

curl --trace-config ids,http/2 https://example.com

Added in 8.3.0. See also -v, --verbose and --trace.

--trace-ids

Prepends the transfer and connection identifiers to each trace or verbose line that curl displays.

This option is global and does not need to be specified for each use of --next.

Providing --trace-ids multiple times has no extra effect. Disable it again with --no-trace-ids.

Example:

curl --trace-ids --trace-ascii output https://example.com

Added in 8.2.0. See also --trace and -v, --verbose.

--trace-time

Prepends a time stamp to each trace or verbose line that curl displays.

This option is global and does not need to be specified for each use of --next.

Providing --trace-time multiple times has no extra effect. Disable it again with --no-trace-time.

Example:

curl --trace-time --trace-ascii output https://example.com

See also --trace and -v, --verbose.

--unix-socket

(HTTP) Connect through this Unix domain socket, instead of using the network.

If --unix-socket is provided several times, the last set value is used.

Example:

curl --unix-socket socket-path https://example.com

See also --abstract-unix-socket.

-T, --upload-file

Upload the specified local file to the remote URL.

If there is no file part in the specified URL, curl appends the local file name to the end of the URL before the operation starts. You must use a trailing slash (/) on the last directory to prove to curl that there is no filename or curl thinks that your last directory name is the remote filename to use.

When putting the local filename at the end of the URL, curl ignores what is on the left side of any slash (/) or backslash (\) used in the filename and only appends what is on the right side of the rightmost such character.

Use the filename "-" (a single dash) to use stdin instead of a given file. Alternately, the filename "." (a single period) may be specified instead of "-" to use stdin in non-blocking mode to allow reading server output while stdin is being uploaded.

If this option is used with an HTTP(S) URL, the PUT method is used.

You can specify one -T, --upload-file for each URL on the command line. Each -T, --upload-file + URL pair specifies what to upload and to where. curl also supports globbing of the -T, --upload-file argument, meaning that you can upload multiple files to a single URL by using the same URL globbing style supported in the URL.

When uploading to an SMTP server: the uploaded data is assumed to be RFC 5322 formatted. It has to feature the necessary set of headers and mail body formatted correctly by the user as curl does not transcode nor encode it further in any way.

--upload-file is associated with a single URL. Use it once per URL when you use several URLs in a command line.

Examples:

curl -T file https://example.com curl -T "img[1-1000].png" ftp://ftp.example.com/ curl --upload-file "{file1,file2}" https://example.com curl -T file -T file2 https://example.com https://example.com

See also -G, --get, -I, --head, -X, --request and -d, --data.

--url

Specify a URL to fetch or send data to.

If the given URL is missing a scheme (such as "http://" or "ftp://" etc) curl guesses which scheme to use based on the hostname. If the outermost subdomain name matches DICT, FTP, IMAP, LDAP, POP3 or SMTP case insensitively, then that protocol is used, otherwise it assumes HTTP. Scheme guessing can be avoided by providing a full URL including the scheme, or disabled by setting a default protocol, see --proto-default for details.

To control where the contents of a retrieved URL is written instead of the default stdout, use the -o, --output or the -O, --remote-name options. When retrieving multiple URLs in a single invoke, each provided URL needs its own dedicated destination option unless --remote-name-all is used.

On Windows, "file://" accesses can be converted to network accesses by the operating system.

--url can be used several times in a command line

Example:

curl --url https://example.com

See also -:, --next and -K, --config.

--url-query

(all) Add a piece of data, usually a name + value pair, to the end of the URL query part. The syntax is identical to that used for --data-urlencode with one extension:

If the argument starts with a '+' (plus), the rest of the string is provided as-is unencoded.

The query part of a URL is the one following the question mark on the right end.

--url-query can be used several times in a command line

Examples:

curl --url-query name=val https://example.com curl --url-query =encodethis http://example.net/foo curl --url-query name@file https://example.com curl --url-query @fileonly https://example.com curl --url-query "+name=%20foo" https://example.com

Added in 7.87.0. See also --data-urlencode and -G, --get.

-B, --use-ascii

(FTP LDAP) Enable ASCII transfer mode. For FTP, this can also be enforced by using a URL that ends with ";type=A". This option causes data sent to stdout to be in text mode for Win32 systems.

Providing --use-ascii multiple times has no extra effect. Disable it again with --no-use-ascii.

Example:

curl -B ftp://example.com/README

See also --crlf and --data-ascii.

-u, --user user:password

Specify the username and password to use for server authentication. Overrides -n, --netrc and --netrc-optional.

If you simply specify the username, curl prompts for a password.

The username and passwords are split up on the first colon, which makes it impossible to use a colon in the username with this option. The password can, still.

On systems where it works, curl hides the given option argument from process listings. This is not enough to protect credentials from possibly getting seen by other users on the same system as they still are visible for a moment before cleared. Such sensitive data should be retrieved from a file instead or similar and never used in clear text in a command line.

When using Kerberos V5 with a Windows based server you should include the Windows domain name in the username, in order for the server to successfully obtain a Kerberos Ticket. If you do not, then the initial authentication handshake may fail.

When using NTLM, the username can be specified simply as the username, without the domain, if there is a single domain and forest in your setup for example.

To specify the domain name use either Down-Level Logon Name or UPN (User Principal Name) formats. For example, EXAMPLE\user and user@example.com respectively.

If you use a Windows SSPI-enabled curl binary and perform Kerberos V5, Negotiate, NTLM or Digest authentication then you can tell curl to select the username and password from your environment by specifying a single colon with this option: "-u :".

If --user is provided several times, the last set value is used.

Example:

curl -u user:secret https://example.com

See also -n, --netrc and -K, --config.

-A, --user-agent

(HTTP) Specify the User-Agent string to send to the HTTP server. To encode blanks in the string, surround the string with single quote marks. This header can also be set with the -H, --header or the --proxy-header options.

If you give an empty argument to -A, --user-agent (""), it removes the header completely from the request. If you prefer a blank header, you can set it to a single space (" ").

By default, curl uses curl/VERSION, such as User-Agent: curl/8.11.1.

If --user-agent is provided several times, the last set value is used.

Example:

curl -A "Agent 007" https://example.com

See also -H, --header and --proxy-header.

--variable <[%]name=text/@file>

Set a variable with "name=content" or "name@file" (where "file" can be stdin if set to a single dash ("-")). The name is a case sensitive identifier that must consist of no other letters than a-z, A-Z, 0-9 or underscore. The specified content is then associated with this identifier.

Setting the same variable name again overwrites the old contents with the new.

The contents of a variable can be referenced in a later command line option when that option name is prefixed with "--expand-", and the name is used as "{{name}}".

--variable can import environment variables into the name space. Opt to either require the environment variable to be set or provide a default value for the variable in case it is not already set.

--variable %name imports the variable called "name" but exits with an error if that environment variable is not already set. To provide a default value if the environment variable is not set, use --variable %name=content or --variable %name@content. Note that on some systems - but not all - environment variables are case insensitive.

When expanding variables, curl supports a set of functions that can make the variable contents more convenient to use. You apply a function to a variable expansion by adding a colon and then list the desired functions in a comma-separated list that is evaluated in a left-to-right order. Variable content holding null bytes that are not encoded when expanded, causes an error.

Available functions:

trim

removes all leading and trailing white space.

json

outputs the content using JSON string quoting rules.

url

shows the content URL (percent) encoded.

b64

expands the variable base64 encoded

--variable can be used several times in a command line

Example:

curl --variable name=smith --expand-url "https://example.com/{{name}}"

Added in 8.3.0. See also -K, --config.

-v, --verbose

Makes curl verbose during the operation. Useful for debugging and seeing what's going on under the hood. A line starting with > means header data sent by curl, < means header data received by curl that is hidden in normal cases, and a line starting with * means additional info provided by curl.

If you only want HTTP headers in the output, -i, --show-headers or -D, --dump-header might be more suitable options.

Since curl 8.10, mentioning this option several times in the same argument increases the level of the trace output. However, as before, a single -v, --verbose or --no-verbose reverts any additions by previous "-vv" again. This means that "-vv -v" is equivalent to a single -v. This avoids unwanted verbosity when the option is mentioned in the command line and curl config files.

Using it twice, e.g. "-vv", outputs time (--trace-time) and transfer ids (--trace-ids), as well as enable tracing for all protocols (--trace-config protocol).

Adding a third verbose outputs transfer content (--trace-ascii %) and enable tracing of more components (--trace-config read,write,ssl).

A forth time adds tracing of all network components. (--trace-config network).

Any addition of the verbose option after that has no effect.

If you think this option does not give you the right details, consider using --trace or --trace-ascii instead. Or use it only once and use --trace-config to trace the specific components you wish to see.

Note that verbose output of curl activities and network traffic might contain sensitive data, including usernames, credentials or secret data content. Be aware and be careful when sharing trace logs with others.

This option is global and does not need to be specified for each use of --next.

Providing --verbose multiple times has no extra effect. Disable it again with --no-verbose.

Example:

curl --verbose https://example.com

This option is mutually exclusive with --trace and --trace-ascii. See also -i, --show-headers, -s, --silent, --trace and --trace-ascii.

-V, --version

Displays information about curl and the libcurl version it uses.

The first line includes the full version of curl, libcurl and other 3rd party libraries linked with the executable.

The second line (starts with "Release-Date:") shows the release date.

The third line (starts with "Protocols:") shows all protocols that libcurl reports to support.

The fourth line (starts with "Features:") shows specific features libcurl reports to offer. Available features include:

alt-svc

Support for the Alt-Svc: header is provided.

AsynchDNS

This curl uses asynchronous name resolves. Asynchronous name resolves can be done using either the c-ares or the threaded resolver backends.

brotli

Support for automatic brotli compression over HTTP(S).

CharConv

curl was built with support for character set conversions (like EBCDIC)

Debug

This curl uses a libcurl built with Debug. This enables more error-tracking and memory debugging etc. For curl-developers only.

ECH

ECH support is present.

gsasl

The built-in SASL authentication includes extensions to support SCRAM because libcurl was built with libgsasl.

GSS-API

GSS-API is supported.

HSTS

HSTS support is present.

HTTP2

HTTP/2 support has been built-in.

HTTP3

HTTP/3 support has been built-in.

HTTPS-proxy

This curl is built to support HTTPS proxy.

IDN

This curl supports IDN - international domain names.

IPv6

You can use IPv6 with this.

Kerberos

Kerberos V5 authentication is supported.

Largefile

This curl supports transfers of large files, files larger than 2GB.

libz

Automatic decompression (via gzip, deflate) of compressed files over HTTP is supported.

MultiSSL

This curl supports multiple TLS backends.

NTLM

NTLM authentication is supported.

NTLM_WB

NTLM delegation to winbind helper is supported. This feature was removed from curl in 8.8.0.

PSL

PSL is short for Public Suffix List and means that this curl has been built with knowledge about "public suffixes".

SPNEGO

SPNEGO authentication is supported.

SSL

SSL versions of various protocols are supported, such as HTTPS, FTPS, POP3S and so on.

SSPI

SSPI is supported.

TLS-SRP

SRP (Secure Remote Password) authentication is supported for TLS.

TrackMemory

Debug memory tracking is supported.

Unicode

Unicode support on Windows.

UnixSockets

Unix sockets support is provided.

zstd

Automatic decompression (via zstd) of compressed files over HTTP is supported.

Example:

curl --version

See also -h, --help and -M, --manual.

--vlan-priority

(All) Set VLAN priority as defined in IEEE 802.1Q.

This field is set on Ethernet level, and only works within a local network.

The valid range for is 0 to 7.

If --vlan-priority is provided several times, the last set value is used.

Example:

curl --vlan-priority 4 https://example.com

Added in 8.9.0. See also --ip-tos.

-w, --write-out

Make curl display information on stdout after a completed transfer. The format is a string that may contain plain text mixed with any number of variables. The format can be specified as a literal "string", or you can have curl read the format from a file with "@filename" and to tell curl to read the format from stdin you write "@-".

The variables present in the output format are substituted by the value or text that curl thinks fit, as described below. All variables are specified as %{variable_name} and to output a normal % you just write them as %%. You can output a newline by using \n, a carriage return with \r and a tab space with \t.

The output is by default written to standard output, but can be changed with %{stderr} and %output{}.

Output HTTP headers from the most recent request by using %header{name} where name is the case insensitive name of the header (without the trailing colon). The header contents are exactly as sent over the network, with leading and trailing whitespace trimmed (added in 7.84.0).

Select a specific target destination file to write the output to, by using %output{name} (added in curl 8.3.0) where name is the full filename. The output following that instruction is then written to that file. More than one %output{} instruction can be specified in the same write-out argument. If the filename cannot be created, curl leaves the output destination to the one used prior to the %output{} instruction. Use %output{>>name} to append data to an existing file.

This output is done independently of if the file transfer was successful or not.

If the specified action or output specified with this option fails in any way, it does not make curl return a (different) error.

NOTE: On Windows, the %-symbol is a special symbol used to expand environment variables. In batch files, all occurrences of % must be doubled when using this option to properly escape. If this option is used at the command prompt then the % cannot be escaped and unintended expansion is possible.

The variables available are:

certs

Output the certificate chain with details. Supported only by the OpenSSL, GnuTLS, Schannel and Secure Transport backends. (Added in 7.88.0)

conn_id

The connection identifier last used by the transfer. The connection id is unique number among all connections using the same connection cache. (Added in 8.2.0)

content_type

The Content-Type of the requested document, if there was any.

errormsg

The error message. (Added in 7.75.0)

exitcode

The numerical exit code of the transfer. (Added in 7.75.0)

filename_effective

The ultimate filename that curl writes out to. This is only meaningful if curl is told to write to a file with the -O, --remote-name or -o, --output option. It is most useful in combination with the -J, --remote-header-name option.

ftp_entry_path

The initial path curl ended up in when logging on to the remote FTP server.

header_json

A JSON object with all HTTP response headers from the recent transfer. Values are provided as arrays, since in the case of multiple headers there can be multiple values. (Added in 7.83.0)

The header names provided in lowercase, listed in order of appearance over the wire. Except for duplicated headers. They are grouped on the first occurrence of that header, each value is presented in the JSON array.

http_code

The numerical response code that was found in the last retrieved HTTP(S) or FTP(s) transfer.

http_connect

The numerical code that was found in the last response (from a proxy) to a curl CONNECT request.

http_version

The http version that was effectively used.

json

A JSON object with all available keys. (Added in 7.70.0)

local_ip

The IP address of the local end of the most recently done connection - can be either IPv4 or IPv6.

local_port

The local port number of the most recently done connection.

method

The http method used in the most recent HTTP request. (Added in 7.72.0)

num_certs

Number of server certificates received in the TLS handshake. Supported only by the OpenSSL, GnuTLS, Schannel and Secure Transport backends. (Added in 7.88.0)

num_connects

Number of new connects made in the recent transfer.

num_headers

The number of response headers in the most recent request (restarted at each redirect). Note that the status line IS NOT a header. (Added in 7.73.0)

num_redirects

Number of redirects that were followed in the request.

num_retries

Number of retries actually performed when "--retry" has been used. (Added in 8.9.0)

onerror

The rest of the output is only shown if the transfer returned a non-zero error. (Added in 7.75.0)

proxy_ssl_verify_result

The result of the HTTPS proxy's SSL peer certificate verification that was requested. 0 means the verification was successful.

proxy_used

Returns 1 if the previous transfer used a proxy, otherwise 0. Useful to for example determine if a "NOPROXY" pattern matched the hostname or not. (Added in 8.7.0)

redirect_url

When an HTTP request was made without -L, --location to follow redirects (or when --max-redirs is met), this variable shows the actual URL a redirect would have gone to.

referer

The Referer: header, if there was any. (Added in 7.76.0)

remote_ip

The remote IP address of the most recently done connection - can be either IPv4 or IPv6.

remote_port

The remote port number of the most recently done connection.

response_code

The numerical response code that was found in the last transfer (formerly known as "http_code").

scheme

The URL scheme (sometimes called protocol) that was effectively used.

size_download

The total amount of bytes that were downloaded. This is the size of the body/data that was transferred, excluding headers.

size_header

The total amount of bytes of the downloaded headers.

size_request

The total amount of bytes that were sent in the HTTP request.

size_upload

The total amount of bytes that were uploaded. This is the size of the body/data that was transferred, excluding headers.

speed_download

The average download speed that curl measured for the complete download. Bytes per second.

speed_upload

The average upload speed that curl measured for the complete upload. Bytes per second.

ssl_verify_result

The result of the SSL peer certificate verification that was requested. 0 means the verification was successful.

stderr

From this point on, the -w, --write-out output is written to standard error. (Added in 7.63.0)

stdout

From this point on, the -w, --write-out output is written to standard output. This is the default, but can be used to switch back after switching to stderr. (Added in 7.63.0)

time_appconnect

The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed.

time_connect

The time, in seconds, it took from the start until the TCP connect to the remote host (or proxy) was completed.

time_namelookup

The time, in seconds, it took from the start until the name resolving was completed.

time_posttransfer

The time it took from the start until the last byte is sent by libcurl. In microseconds. (Added in 8.10.0)

time_pretransfer

The time, in seconds, it took from the start until the file transfer was just about to begin. This includes all pre-transfer commands and negotiations that are specific to the particular protocol(s) involved.

time_redirect

The time, in seconds, it took for all redirection steps including name lookup, connect, pretransfer and transfer before the final transaction was started. "time_redirect" shows the complete execution time for multiple redirections.

time_starttransfer

The time, in seconds, it took from the start until the first byte is received. This includes time_pretransfer and also the time the server needed to calculate the result.

time_total

The total time, in seconds, that the full operation lasted.

url

The URL that was fetched. (Added in 7.75.0)

url.scheme

The scheme part of the URL that was fetched. (Added in 8.1.0)

url.user

The user part of the URL that was fetched. (Added in 8.1.0)

url.password

The password part of the URL that was fetched. (Added in 8.1.0)

url.options

The options part of the URL that was fetched. (Added in 8.1.0)

url.host

The host part of the URL that was fetched. (Added in 8.1.0)

url.port

The port number of the URL that was fetched. If no port number was specified and the URL scheme is known, that scheme's default port number is shown. (Added in 8.1.0)

url.path

The path part of the URL that was fetched. (Added in 8.1.0)

url.query

The query part of the URL that was fetched. (Added in 8.1.0)

url.fragment

The fragment part of the URL that was fetched. (Added in 8.1.0)

url.zoneid

The zone id part of the URL that was fetched. (Added in 8.1.0)

urle.scheme

The scheme part of the effective (last) URL that was fetched. (Added in 8.1.0)

urle.user

The user part of the effective (last) URL that was fetched. (Added in 8.1.0)

urle.password

The password part of the effective (last) URL that was fetched. (Added in 8.1.0)

urle.options

The options part of the effective (last) URL that was fetched. (Added in 8.1.0)

urle.host

The host part of the effective (last) URL that was fetched. (Added in 8.1.0)

urle.port

The port number of the effective (last) URL that was fetched. If no port number was specified, but the URL scheme is known, that scheme's default port number is shown. (Added in 8.1.0)

urle.path

The path part of the effective (last) URL that was fetched. (Added in 8.1.0)

urle.query

The query part of the effective (last) URL that was fetched. (Added in 8.1.0)

urle.fragment

The fragment part of the effective (last) URL that was fetched. (Added in 8.1.0)

urle.zoneid

The zone id part of the effective (last) URL that was fetched. (Added in 8.1.0)

urlnum

The URL index number of this transfer, 0-indexed. Unglobbed URLs share the same index number as the origin globbed URL. (Added in 7.75.0)

url_effective

The URL that was fetched last. This is most meaningful if you have told curl to follow location: headers.

xfer_id

The numerical identifier of the last transfer done. -1 if no transfer has been started yet for the handle. The transfer id is unique among all transfers performed using the same connection cache. (Added in 8.2.0)

If --write-out is provided several times, the last set value is used.

Example:

curl -w '%{response_code}\n' https://example.com

See also -v, --verbose and -I, --head.

--xattr

When saving output to a file, tell curl to store file metadata in extended file attributes. Currently, "curl" is stored in the "creator" attribute, the URL is stored in the "xdg.origin.url" attribute and, for HTTP, the content type is stored in the "mime_type" attribute. If the file system does not support extended attributes, a warning is issued.

Providing --xattr multiple times has no extra effect. Disable it again with --no-xattr.

Example:

curl --xattr -o storage https://example.com

See also -R, --remote-time, -w, --write-out and -v, --verbose.

Files

~/.curlrc

Default config file, see -K, --config for details.

Environment

The environment variables can be specified in lower case or upper case. The lower case version has precedence. "http_proxy" is an exception as it is only available in lower case.

Using an environment variable to set the proxy has the same effect as using the -x, --proxy option.

http_proxy [protocol://][:port]

Sets the proxy server to use for HTTP.

HTTPS_PROXY [protocol://][:port]

Sets the proxy server to use for HTTPS.

[url-protocol]_PROXY [protocol://][:port]

Sets the proxy server to use for [url-protocol], where the protocol is a protocol that curl supports and as specified in a URL. FTP, FTPS, POP3, IMAP, SMTP, LDAP, etc.

ALL_PROXY [protocol://][:port]

Sets the proxy server to use if no protocol-specific proxy is set.

NO_PROXY <comma-separated list of hosts/domains>

list of hostnames that should not go through any proxy. If set to an asterisk '*' only, it matches all hosts. Each name in this list is matched as either a domain name which contains the hostname, or the hostname itself.

This environment variable disables use of the proxy even when specified with the -x, --proxy option. That is

NO_PROXY=direct.example.com curl -x http://proxy.example.com http://direct.example.com

accesses the target URL directly, and

NO_PROXY=direct.example.com curl -x http://proxy.example.com http://somewhere.example.com

accesses the target URL through the proxy.

The list of hostnames can also be include numerical IP addresses, and IPv6 versions should then be given without enclosing brackets.

IP addresses can be specified using CIDR notation: an appended slash and number specifies the number of "network bits" out of the address to use in the comparison (added in 7.86.0). For example "192.168.0.0/16" would match all addresses starting with "192.168".

APPDATA

On Windows, this variable is used when trying to find the home directory. If the primary home variable are all unset.

COLUMNS

If set, the specified number of characters is used as the terminal width when the alternative progress-bar is shown. If not set, curl tries to figure it out using other ways.

CURL_CA_BUNDLE

If set, it is used as the --cacert value. This environment variable is ignored if Schannel is used as the TLS backend.

CURL_HOME

If set, is the first variable curl checks when trying to find its home directory. If not set, it continues to check XDG_CONFIG_HOME

CURL_SSL_BACKEND

If curl was built with support for "MultiSSL", meaning that it has built-in support for more than one TLS backend, this environment variable can be set to the case insensitive name of the particular backend to use when curl is invoked. Setting a name that is not a built-in alternative makes curl stay with the default.

SSL backend names (case-insensitive): bearssl, gnutls, mbedtls, openssl, rustls, schannel, secure-transport, wolfssl

HOME

If set, this is used to find the home directory when that is needed. Like when looking for the default .curlrc. CURL_HOME and XDG_CONFIG_HOME have preference.

QLOGDIR

If curl was built with HTTP/3 support, setting this environment variable to a local directory makes curl produce qlogs in that directory, using file names named after the destination connection id (in hex). Do note that these files can become rather large. Works with the ngtcp2 and quiche QUIC backends.

SHELL

Used on VMS when trying to detect if using a DCL or a Unix shell.

SSL_CERT_DIR

If set, it is used as the --capath value. This environment variable is ignored if Schannel is used as the TLS backend.

SSL_CERT_FILE

If set, it is used as the --cacert value. This environment variable is ignored if Schannel is used as the TLS backend.

SSLKEYLOGFILE

If you set this environment variable to a filename, curl stores TLS secrets from its connections in that file when invoked to enable you to analyze the TLS traffic in real time using network analyzing tools such as Wireshark. This works with the following TLS backends: OpenSSL, LibreSSL (TLS 1.2 max), BoringSSL, GnuTLS and wolfSSL.

USERPROFILE

On Windows, this variable is used when trying to find the home directory. If the other, primary, variable are all unset. If set, curl uses the path "$USERPROFILE\Application Data".

XDG_CONFIG_HOME

If CURL_HOME is not set, this variable is checked when looking for a default .curlrc file.

Proxy protocol prefixes

The proxy string may be specified with a protocol:// prefix to specify alternative proxy protocols.

If no protocol is specified in the proxy string or if the string does not match a supported one, the proxy is treated as an HTTP proxy.

The supported proxy protocol prefixes are as follows:

http://

Makes it use it as an HTTP proxy. The default if no scheme prefix is used.

https://

Makes it treated as an HTTPS proxy.

socks4://

Makes it the equivalent of --socks4

socks4a://

Makes it the equivalent of --socks4a

socks5://

Makes it the equivalent of --socks5

socks5h://

Makes it the equivalent of --socks5-hostname

Exit codes

There are a bunch of different error codes and their corresponding error messages that may appear under error conditions. At the time of this writing, the exit codes are:

0

Success. The operation completed successfully according to the instructions.

1

Unsupported protocol. This build of curl has no support for this protocol.

2

Failed to initialize.

3

URL malformed. The syntax was not correct.

4

A feature or option that was needed to perform the desired request was not enabled or was explicitly disabled at build-time. To make curl able to do this, you probably need another build of libcurl.

5

Could not resolve proxy. The given proxy host could not be resolved.

6

Could not resolve host. The given remote host could not be resolved.

7

Failed to connect to host.

8

Weird server reply. The server sent data curl could not parse.

9

FTP access denied. The server denied login or denied access to the particular resource or directory you wanted to reach. Most often you tried to change to a directory that does not exist on the server.

10

FTP accept failed. While waiting for the server to connect back when an active FTP session is used, an error code was sent over the control connection or similar.

11

FTP weird PASS reply. Curl could not parse the reply sent to the PASS request.

12

During an active FTP session while waiting for the server to connect back to curl, the timeout expired.

13

FTP weird PASV reply, Curl could not parse the reply sent to the PASV request.

14

FTP weird 227 format. Curl could not parse the 227-line the server sent.

15

FTP cannot use host. Could not resolve the host IP we got in the 227-line.

16

HTTP/2 error. A problem was detected in the HTTP2 framing layer. This is somewhat generic and can be one out of several problems, see the error message for details.

17

FTP could not set binary. Could not change transfer method to binary.

18

Partial file. Only a part of the file was transferred.

19

FTP could not download/access the given file, the RETR (or similar) command failed.

21

FTP quote error. A quote command returned error from the server.

22

HTTP page not retrieved. The requested URL was not found or returned another error with the HTTP error code being 400 or above. This return code only appears if -f, --fail is used.

23

Write error. Curl could not write data to a local filesystem or similar.

25

Failed starting the upload. For FTP, the server typically denied the STOR command.

26

Read error. Various reading problems.

27

Out of memory. A memory allocation request failed.

28

Operation timeout. The specified time-out period was reached according to the conditions.

30

FTP PORT failed. The PORT command failed. Not all FTP servers support the PORT command, try doing a transfer using PASV instead.

31

FTP could not use REST. The REST command failed. This command is used for resumed FTP transfers.

33

HTTP range error. The range "command" did not work.

34

HTTP post error. Internal post-request generation error.

35

SSL connect error. The SSL handshaking failed.

36

Bad download resume. Could not continue an earlier aborted download.

37

FILE could not read file. Failed to open the file. Permissions?

38

LDAP cannot bind. LDAP bind operation failed.

39

LDAP search failed.

41

Function not found. A required LDAP function was not found.

42

Aborted by callback. An application told curl to abort the operation.

43

Internal error. A function was called with a bad parameter.

45

Interface error. A specified outgoing interface could not be used.

47

Too many redirects. When following redirects, curl hit the maximum amount.

48

Unknown option specified to libcurl. This indicates that you passed a weird option to curl that was passed on to libcurl and rejected. Read up in the manual.

49

Malformed telnet option.

52

The server did not reply anything, which here is considered an error.

53

SSL crypto engine not found.

54

Cannot set SSL crypto engine as default.

55

Failed sending network data.

56

Failure in receiving network data.

58

Problem with the local certificate.

59

Could not use specified SSL cipher.

60

Peer certificate cannot be authenticated with known CA certificates.

61

Unrecognized transfer encoding.

63

Maximum file size exceeded.

64

Requested FTP SSL level failed.

65

Sending the data requires a rewind that failed.

66

Failed to initialize SSL Engine.

67

The username, password, or similar was not accepted and curl failed to log in.

68

File not found on TFTP server.

69

Permission problem on TFTP server.

70

Out of disk space on TFTP server.

71

Illegal TFTP operation.

72

Unknown TFTP transfer ID.

73

File already exists (TFTP).

74

No such user (TFTP).

77

Problem reading the SSL CA cert (path? access rights?).

78

The resource referenced in the URL does not exist.

79

An unspecified error occurred during the SSH session.

80

Failed to shut down the SSL connection.

82

Could not load CRL file, missing or wrong format.

83

Issuer check failed.

84

The FTP PRET command failed.

85

Mismatch of RTSP CSeq numbers.

86

Mismatch of RTSP Session Identifiers.

87

Unable to parse FTP file list.

88

FTP chunk callback reported error.

89

No connection available, the session is queued.

90

SSL public key does not matched pinned public key.

91

Invalid SSL certificate status.

92

Stream error in HTTP/2 framing layer.

93

An API function was called from inside a callback.

94

An authentication function returned an error.

95

A problem was detected in the HTTP/3 layer. This is somewhat generic and can be one out of several problems, see the error message for details.

96

QUIC connection error. This error may be caused by an SSL library error. QUIC is the protocol used for HTTP/3 transfers.

97

Proxy handshake error.

98

A client-side certificate is required to complete the TLS handshake.

99

Poll or select returned fatal error.

100

A value or data field grew larger than allowed.

XX

More error codes might appear here in future releases. The existing ones are meant to never change.

Bugs

If you experience any problems with curl, submit an issue in the project's bug tracker on GitHub: https://github.com/curl/curl/issues

Authors

Daniel Stenberg is the main author, but the whole list of contributors is found in the separate THANKS file.

Www

https://curl.se

See also

ftp (1), wget (1)

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