SC2209 – ShellCheck Wiki

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Use var=$(command) to assign output (or quote to assign string).

Problematic code:

user=whoami         # Want to run whoami and assign output

PAGER=cat git log   # Want to assign the string "cat"

Correct code:

user=$(whoami)

PAGER="cat" git log

Rationale:

Putting var= in front of a command will not assign its output. Use var=$(my command here) to execute the command and capture its output.

If you do want to assign a literal string, use quotes to make this clear to shellcheck and humans alike.

Exceptions:

None.

Quoting a single command (as in PAGER="cat" above) doesn't change how the script works. It's purely to show shellcheck (and humans) that a literal assignment of a command name is intentional.

This warning triggers generally when a variable is assigned an unquoted command name (from a list of hard coded names). See related warning SC2037 which detects the same kind of error through the patterns var=value -flag and var=value *glob*.

Related resources:

• BashFaq: How can I store the return value and/or output of a command in a variable?
• StackOverflow: How to set a variable to the output from a command in Bash

ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.