curl/docs/cmdline-opts/variable.md
Daniel Stenberg 2494b8dd51
docs/cmdline: change to .md for cmdline docs
- switch all invidual files documenting command line options into .md,
   as the documentation is now markdown-looking.

 - made the parser treat 4-space indents as quotes

 - switch to building the curl.1 manpage using the "mainpage.idx" file,
   which lists the files to include to generate it, instead of using the
   previous page-footer/headers. Also, those files are now also .md
   ones, using the same format. I gave them underscore prefixes to make
   them sort separately:
   _NAME.md, _SYNOPSIS.md, _DESCRIPTION.md, _URL.md, _GLOBBING.md,
   _VARIABLES.md, _OUTPUT.md, _PROTOCOLS.md, _PROGRESS.md, _VERSION.md,
   _OPTIONS.md, _FILES.md, _ENVIRONMENT.md, _PROXYPREFIX.md,
   _EXITCODES.md, _BUGS.md, _AUTHORS.md, _WWW.md, _SEEALSO.md

 - updated test cases accordingly

Closes #12751
2024-01-23 14:30:15 +01:00

1.9 KiB

c SPDX-License-Identifier Long Arg Help Category Added Multi See-also Example
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. curl variable <[%]name=text/@file> Set variable curl 8.3.0 append
config
--variable name=smith $URL

--variable

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}}" (without the quotes).

--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