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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. 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 or TFTP. The command is designed
to work without user interaction.

curl offers a busload of useful tricks like proxy support, user authentication, FTP upload,
HTTP post, SSL connections, cookies, file transfer resume and more. As you will see below,
the number of features will make your head spin.

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.

You can specify multiple URLs or parts of URLs by writing part sets within braces and quoting
the URL as in:

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

or you can get sequences of alphanumeric series by using [] as in:

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

"ftp://ftp.example.com/file[001-100].txt" (with leading zeros)

"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 any amount of URLs on the command line. They will be fetched in a sequential
manner in the specified order. You can specify command line options and URLs mixed and in any
order on the command line.

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 '*'.

Provide the IPv6 zone index in the URL with an escaped percentage sign and the interface
name. Like in

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

If you specify URL without protocol:// prefix, curl will attempt to guess what protocol you
might want. It will then default to HTTP but try other protocols based on often-used host
name prefixes. For example, for host names starting with "ftp." curl will assume you want to
speak FTP.

curl will do its best to use what you pass to it as a URL. It is not trying to validate it as
a syntactically correct URL by any means but is fairly liberal with what it accepts.

curl will attempt to re-use connections for multiple file transfers, so that getting many
files from the same server will not do multiple connects / handshakes. This improves speed.
Of course this is only done on files specified on a single command line and cannot be used
between separate curl invocations.

OUTPUT
If not told otherwise, curl writes the received data to stdout. It can be instructed to in‐
stead 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
options 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 using the native UNC approach will work.

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 options and the correct command line op‐
tions.

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 "subscribe" 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 server 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 trans‐
ferred data, transfer speeds and estimated time left, etc. The progress meter displays number
of bytes and the speeds are 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.

OPTIONS
Options start with one or two dashes. Many of the options require an additional value next to
them.

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 "dou‐
ble-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.

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

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 will be used. After a completed transfer, the cache
will be 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 will load contents from all the files but
the last one will be used for saving.

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 se‐
cure one the remote site claims to support. This is done by first doing a request and
checking the response-headers, thus possibly inducing an extra network round-trip.
This is used instead of setting a specific authentication 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 will fail.

Used together with -u, --user.

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 makes curl append to the target file instead
of overwriting it. If the remote file does not exist, it will be created. Note that
this flag is ignored by some SFTP servers (including OpenSSH).

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

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

--aws-sigv4 <provider1[:provider2[:region[:service]]]>
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 col‐
lection (region-code) when the region name is omitted from the endpoint.

The service argument is a string that points to a function provided by a cloud (ser‐
vice-code) when the service name is omitted from the endpoint.

Example:
curl --aws-sigv4 "aws:amz: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 remote host. This is the
default and this option is usually pointless, unless you use it to override a previ‐
ously set option that sets a different authentication method (such as --ntlm, --di‐
gest, or --negotiate).

Used together with -u, --user.

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