var=$(command)to assign output (or quote to assign string).
user=whoami # Want to run whoami and assign output PAGER=cat git log # Want to assign the string "cat"
user=$(whoami) PAGER="cat" git log
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.
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
ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.