| <!-- Copyright (C) Daniel Stenberg, <[email protected]>, 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 access and expand environment variables by first importing them. You | |
| 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`. | |
| To apply functions 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 when | |
| 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. | |