111 lines
3.4 KiB
Markdown
111 lines
3.4 KiB
Markdown
---
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c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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Long: variable
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Arg: <[%]name=text/@file>
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Help: Set variable
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Category: curl
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Added: 8.3.0
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Multi: append
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See-also:
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- config
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Example:
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- --variable name=smith --expand-url "$URL/{{name}}"
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---
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# `--variable`
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Set a variable with `name=content` or `name@file` (where `file` can be stdin
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if set to a single dash (`-`)). The name is a case sensitive identifier that
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must consist of no other letters than a-z, A-Z, 0-9 or underscore. The
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specified content is then associated with this identifier.
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Setting the same variable name again overwrites the old contents with the new.
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The contents of a variable can be referenced in a later command line option
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when that option name is prefixed with `--expand-`, and the name is used as
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`{{name}}`.
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--variable can import environment variables into the name space. Opt to either
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require the environment variable to be set or provide a default value for the
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variable in case it is not already set.
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--variable %name imports the variable called `name` but exits with an error if
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that environment variable is not already set. To provide a default value if
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the environment variable is not set, use --variable %name=content or
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--variable %name@content. Note that on some systems - but not all -
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environment variables are case insensitive.
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Added in curl 8.12.0: you can get a byte range from the source by appending
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`[start-end]` to the variable name, where *start* and *end* are byte offsets
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to include from the contents. For example, asking for offset "2-10" means
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offset two to offset ten, inclusive, resulting in 9 bytes in total. `2-2`
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means a single byte at offset 2. Not providing a second number implies to the
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end of data. The start offset cannot be larger than the end offset. Asking for
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a range that is outside of the file size makes the variable contents empty.
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For example, getting the first one hundred bytes from a given file:
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curl --variable "fraction[0-99]@filename"
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Given a byte range that has no data results in an empty string. Asking for a
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range that is larger than the content makes curl use the piece of the data
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that exists.
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To assign a variable using contents from another variable, use
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--expand-variable. Like for example assigning a new variable using contents
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from two other:
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curl --expand-variable "user={{firstname}} {{lastname}}"
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When expanding variables, curl supports a set of functions that can make the
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variable contents more convenient to use. You apply a function to a variable
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expansion by adding a colon and then list the desired functions in a
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comma-separated list that is evaluated in a left-to-right order. Variable
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content holding null bytes that are not encoded when expanded, causes an
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error.
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Available functions:
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## `trim`
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removes all leading and trailing white space.
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Example:
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curl --expand-url https://example.com/{{var:trim}}
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## `json`
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outputs the content using JSON string quoting rules.
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Example:
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curl --expand-data {{data:json}} https://example.com
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## `url`
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shows the content URL (percent) encoded.
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Example:
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curl --expand-url https://example.com/{{path:url}}
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## `b64`
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expands the variable base64 encoded
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Example:
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curl --expand-url https://example.com/{{var:b64}}
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## `64dec`
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decodes a base64 encoded character sequence. If the sequence is not possible
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to decode, it instead outputs `[64dec-fail]`
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Example:
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curl --expand-url https://example.com/{{var:64dec}}
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(Added in 8.13.0)
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