curl/docs/cmdline-opts/_VARIABLES.md
RainRat 2cd78f525c misc: Fix typos in docs and lib
This fixes miscellaneous typos and duplicated words in the docs, lib
and test comments and a few user facing errorstrings.

Author: RainRat on Github
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Dan Fandrich <dan@coneharvesters.com>
Closes: #13019
2024-03-01 09:59:48 +01:00

45 lines
2.0 KiB
Markdown

<!-- Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. -->
<!-- SPDX-License-Identifier: curl -->
# 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}}` 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 8.3.0.