PATHis the shell search path. Use another name.
PATH=/my/dir cat "$PATH/myfile"
Good practice: always use lowercase for unexported variables.
path=/my/dir cat "$path/myfile"
Bad practice: use another uppercase name.
MYPATH=/my/dir cat "$MYPATH/myfile"
PATH is where the shell looks for the commands it executes. By inadvertently overwriting it, the shell will be unable to find commands (like
cat in this case).
You get this warning when ShellCheck suspects that you didn't meant to overwrite it (because it's a single path with no path separators).
Best shell scripting practice is to always use lowercase variable names to avoid accidentally overwriting exported and internal variables.
If you're aware of the above and really do want to set your shell search path to
/my/dir, you can ignore this warning.
ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.