case $input in ) echo "Reading from stdin..." ;; - $output ) echo "Input should be different from output" ;; esac
case $input in ) echo "Reading from stdin..." ;; - "$output" ) echo "Input should be different from output" ;; esac
When unquoted variables and command expansions are used in case branch patterns, they will be interpreted as globs.
This can lead to some surprising behavior, such as
case $x in $x) trigger;; esac not triggering in some cases, such as when
x='Pride and Prejudice .epub'.
To match the literal content of the variable or expansion, make sure to double quote the expansion.
If you intended to match a dynamically generated pattern, you can ignore this suggestion with a directive.
[[ $x = $x ]].
ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.