h2-mod/deps/curl/docs/cmdline-opts/page-header

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.TH curl 1 "%DATE" "curl %VERSION" "curl Manual"
.SH NAME
curl \- transfer a URL
.SH SYNOPSIS
.B curl [options / URLs]
.SH 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.
.SH 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 --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 connects 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 option or
its argument, curl assumes is a URL and treats it as such.
.SH 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"

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 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 --globoff.
.SH 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 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 default value if it is not set, use
--variable %name=content or --variable %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 content holding null bytes that are
not encoded when expanded cause error.

Example: get the contents of a file called $HOME/.secret into a variable
called "fix". Make sure that the content is trimmed and percent-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.
.SH 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 --output or
--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.
.SH PROTOCOLS
curl supports numerous protocols, or put in URL terms: schemes. Your
particular build may not support them all.
.IP DICT
Lets you lookup words using online dictionaries.
.IP 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
works.
.IP FTP(S)
curl supports the File Transfer Protocol with a lot of tweaks and levers. With
or without using TLS.
.IP GOPHER(S)
Retrieve files.
.IP 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 options.
.IP IMAP(S)
Using the mail reading protocol, curl can "download" emails for you. With or
without using TLS.
.IP LDAP(S)
curl can do directory lookups for you, with or without TLS.
.IP 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).
.IP POP3(S)
Downloading from a pop3 server means getting a mail. With or without using
TLS.
.IP RTMP(S)
The **Realtime Messaging Protocol** is primarily used to serve streaming media
and curl can download it.
.IP RTSP
curl supports RTSP 1.0 downloads.
.IP SCP
curl supports SSH version 2 scp transfers.
.IP SFTP
curl supports SFTP (draft 5) done over SSH version 2.
.IP SMB(S)
curl supports SMB version 1 for upload and download.
.IP SMTP(S)
Uploading contents to an SMTP server means sending an email. With or without
TLS.
.IP 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.
.IP TFTP
curl can do TFTP downloads and uploads.
.SH "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 (>), --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
--silent option.
.SH 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 incarnation:
https://curl.se/docs/manpage.html
.SH 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, --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:
%GLOBALS.