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curl(1) curl Manual curl(1)

NAME
curl - transfer a URL

SYNOPSIS
curl [options / URLs]

DESCRIPTION
curl is a tool for transferring data from or to a server using URLs. It
supports these protocols: DICT, FILE, FTP, FTPS, GOPHER, GOPHERS, HTTP,
HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, POP3, POP3S, RTMP, RTMPS, RTSP,
SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET, TFTP, WS and WSS.

curl is powered by libcurl for all transfer-related features. See
libcurl(3) for details.

URL
The URL syntax is protocol-dependent. You find a detailed description
in RFC 3986.

If you provide a URL without a leading protocol:// scheme, curl guesses
what protocol you want. It then defaults to HTTP but assumes others
based on often-used host name prefixes. For example, for host names
starting with "ftp." curl assumes you want FTP.

You can specify any amount of URLs on the command line. They are
fetched in a sequential manner in the specified order unless you use
-Z, --parallel. You can specify command line options and URLs mixed and
in any order on the command line.

curl attempts to reuse connections when doing multiple transfers, so
that getting many files from the same server do not use multiple con-
nects and setup handshakes. This improves speed. Connection reuse can
only be done for URLs specified for a single command line invocation
and cannot be performed between separate curl runs.

Provide an IPv6 zone id in the URL with an escaped percentage sign.
Like in

"http://[fe80::3%25eth0]/"

Everything provided on the command line that is not a command line op-
tion or its argument, curl assumes is a URL and treats it as such.

GLOBBING
You can specify multiple URLs or parts of URLs by writing lists within
braces or ranges within brackets. We call this "globbing".

Provide a list with three different names like this:

"http://site.{one,two,three}.com"

Do sequences of alphanumeric series by using [] as in:

"ftp://ftp.example.com/file[1-100].txt"

With leading zeroes:

"ftp://ftp.example.com/file[001-100].txt"

With letters through the alphabet:

"ftp://ftp.example.com/file[a-z].txt"

Nested sequences are not supported, but you can use several ones next
to each other:

"http://example.com/archive[1996-1999]/vol[1-4]/part{a,b,c}.html"

You can specify a step counter for the ranges to get every Nth number
or letter:

"http://example.com/file[1-100:10].txt"

"http://example.com/file[a-z:2].txt"

When using [] or {} sequences when invoked from a command line prompt,
you probably have to put the full URL within double quotes to avoid the
shell from interfering with it. This also goes for other characters
treated special, like for example '&', '?' and '*'.

Switch off globbing with -g, --globoff.

VARIABLES
curl supports command line variables (added in 8.3.0). Set variables
with --variable name=content or --variable name@file (where "file" can
be stdin if set to a single dash (-)).

Variable contents can be expanded in option parameters using "{{name}}"
(without the quotes) if the option name is prefixed with "--expand-".
This gets the contents of the variable "name" inserted, or a blank if
the name does not exist as a variable. Insert "{{" verbatim in the
string by prefixing it with a backslash, like "\{{".

You an access and expand environment variables by first importing them.
You can select to either require the environment variable to be set or
you can provide a default value in case it is not already set. Plain
--variable %name imports the variable called 'name' but exits with an
error if that environment variable is not already set. To provide a de-
fault value if it is not set, use --variable %name=content or --vari-
able %name@content.

Example. Get the USER environment variable into the URL, fail if USER
is not set:

--variable '%USER'
--expand-url = "https://example.com/api/{{USER}}/method"

When expanding variables, curl supports a set of functions that can
make the variable contents more convenient to use. It can trim leading
and trailing white space with trim, it can output the contents as a
JSON quoted string with json, URL encode the string with url or base64
encode it with b64. You apply function to a variable expansion, add
them colon separated to the right side of the variable. Variable con-
tent holding null bytes that are not encoded when expanded cause error.

Example: get the contents of a file called $HOME/.secret into a vari-
able called "fix". Make sure that the content is trimmed and per-
cent-encoded sent as POST data:

--variable %HOME
--expand-variable fix@{{HOME}}/.secret
--expand-data "{{fix:trim:url}}"
https://example.com/

Command line variables and expansions were added in in 8.3.0.

OUTPUT
If not told otherwise, curl writes the received data to stdout. It can
be instructed to instead save that data into a local file, using the
-o, --output or -O, --remote-name options. If curl is given multiple
URLs to transfer on the command line, it similarly needs multiple op-
tions for where to save them.

curl does not parse or otherwise "understand" the content it gets or
writes as output. It does no encoding or decoding, unless explicitly
asked to with dedicated command line options.

PROTOCOLS
curl supports numerous protocols, or put in URL terms: schemes. Your
particular build may not support them all.

DICT Lets you lookup words using online dictionaries.

FILE Read or write local files. curl does not support accessing
file:// URL remotely, but when running on Microsoft Windows us-
ing the native UNC approach works.

FTP(S) curl supports the File Transfer Protocol with a lot of tweaks
and levers. With or without using TLS.

GOPHER(S)
Retrieve files.

HTTP(S)
curl supports HTTP with numerous options and variations. It can
speak HTTP version 0.9, 1.0, 1.1, 2 and 3 depending on build op-
tions and the correct command line options.

IMAP(S)
Using the mail reading protocol, curl can "download" emails for
you. With or without using TLS.

LDAP(S)
curl can do directory lookups for you, with or without TLS.

MQTT curl supports MQTT version 3. Downloading over MQTT equals "sub-
scribe" to a topic while uploading/posting equals "publish" on a
topic. MQTT over TLS is not supported (yet).

POP3(S)
Downloading from a pop3 server means getting a mail. With or
without using TLS.

RTMP(S)
The Realtime Messaging Protocol is primarily used to serve
streaming media and curl can download it.

RTSP curl supports RTSP 1.0 downloads.

SCP curl supports SSH version 2 scp transfers.

SFTP curl supports SFTP (draft 5) done over SSH version 2.

SMB(S) curl supports SMB version 1 for upload and download.

SMTP(S)
Uploading contents to an SMTP server means sending an email.
With or without TLS.

TELNET Telling curl to fetch a telnet URL starts an interactive session
where it sends what it reads on stdin and outputs what the
server sends it.

TFTP curl can do TFTP downloads and uploads.

PROGRESS METER
curl normally displays a progress meter during operations, indicating
the amount of transferred data, transfer speeds and estimated time
left, etc. The progress meter displays the transfer rate in bytes per
second. The suffixes (k, M, G, T, P) are 1024 based. For example 1k is
1024 bytes. 1M is 1048576 bytes.

curl displays this data to the terminal by default, so if you invoke
curl to do an operation and it is about to write data to the terminal,
it disables the progress meter as otherwise it would mess up the output
mixing progress meter and response data.

If you want a progress meter for HTTP POST or PUT requests, you need to
redirect the response output to a file, using shell redirect (>), -o,
--output or similar.

This does not apply to FTP upload as that operation does not spit out
any response data to the terminal.

If you prefer a progress "bar" instead of the regular meter, -#,
--progress-bar is your friend. You can also disable the progress meter
completely with the -s, --silent option.

VERSION
This man page describes curl %VERSION. If you use a later version,
chances are this man page does not fully document it. If you use an
earlier version, this document tries to include version information
about which specific version that introduced changes.

You can always learn which the latest curl version is by running

curl https://curl.se/info

The online version of this man page is always showing the latest incar-
nation: https://curl.se/docs/manpage.html

OPTIONS
Options start with one or two dashes. Many of the options require an
additional value next to them. If provided text does not start with a
dash, it is presumed to be and treated as a URL.

The short "single-dash" form of the options, -d for example, may be
used with or without a space between it and its value, although a space
is a recommended separator. The long "double-dash" form, -d, --data for
example, requires a space between it and its value.

Short version options that do not need any additional values can be
used immediately next to each other, like for example you can specify
all the options -O, -L and -v at once as -OLv.

In general, all boolean options are enabled with --option and yet again
disabled with --no-option. That is, you use the same option name but
prefix it with "no-". However, in this list we mostly only list and
show the --option version of them.

When -:, --next is used, it resets the parser state and you start again
with a clean option state, except for the options that are "global".
Global options retain their values and meaning even after -:, --next.

The following options are global: --fail-early, --libcurl, --paral-
lel-immediate, -Z, --parallel, -#, --progress-bar, --rate, -S,
--show-error, --stderr, --styled-output, --trace-ascii, --trace-config,
--trace-ids, --trace-time, --trace and -v, --verbose.

--abstract-unix-socket <path>
(HTTP) Connect through an abstract Unix domain socket, instead
of using the network. Note: netstat shows the path of an ab-
stract socket prefixed with '@', however the <path> argument
should not have this leading character.

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

Example:
curl --abstract-unix-socket socketpath https://example.com

See also --unix-socket. Added in 7.53.0.

--alt-svc <file name>
(HTTPS) This option enables the alt-svc parser in curl. If the
file name points to an existing alt-svc cache file, that gets
used. After a completed transfer, the cache is saved to the file
name again if it has been modified.

Specify a "" file name (zero length) to avoid loading/saving and
make curl just handle the cache in memory.

If this option is used several times, curl loads contents from
all the files but the last one is used for saving.

--alt-svc can be used several times in a command line

Example:
curl --alt-svc svc.txt https://example.com

See also --resolve and --connect-to. Added in 7.64.1.

--anyauth
(HTTP) Tells curl to figure out authentication method by itself,
and use the most secure one the remote site claims to support.
This is done by first doing a request and checking the re-
sponse-headers, thus possibly inducing an extra network
round-trip. This is used instead of setting a specific authenti-
cation method, which you can do with --basic, --digest, --ntlm,
and --negotiate.

Using --anyauth is not recommended if you do uploads from stdin,
since it may require data to be sent twice and then the client
must be able to rewind. If the need should arise when uploading
from stdin, the upload operation fails.

Used together with -u, --user.

Providing --anyauth multiple times has no extra effect.

Example:
curl --anyauth --user me:pwd https://example.com

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

-a, --append
(FTP SFTP) When used in an upload, this option makes curl append
to the target file instead of overwriting it. If the remote file
does not exist, it is created. Note that this flag is ignored by
some SFTP servers (including OpenSSH).

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

Example:
curl --upload-file local --append ftp://example.com/

See also -r, --range and -C, --continue-at.

--aws-sigv4 <provider1[:provider2[:region[:service]]]>
(HTTP) Use AWS V4 signature authentication in the transfer.

The provider argument is a string that is used by the algorithm
when creating outgoing authentication headers.

The region argument is a string that points to a geographic area
of a resources collection (region-code) when the region name is
omitted from the endpoint.

The service argument is a string that points to a function pro-
vided by a cloud (service-code) when the service name is omitted
from the endpoint.

If --aws-sigv4 is provided several times, the last set value is
used.

Example:
curl --aws-sigv4 "aws:amz:us-east-2:es" --user "key:secret" https://example.com

See also --basic and -u, --user. Added in 7.75.0.

--basic
(HTTP) Tells curl to use HTTP Basic authentication with the re-
mote host. This is the default and this option is usually point-
less, unless you use it to override a previously set option that
sets a different authentication method (such as --ntlm, --di-
gest, or --negotiate).

Used together with -u, --user.

Providing --basic multiple times has no extra effect.

Example:
curl -u name:password --basic https://example.com

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