set var=42 set var 42
set is not used to set or assign variables in Bourne shells. It's used to set shell options and positional parameters.
To assign variables, use
var=value with no
set or other qualifiers.
If you actually do want to set positional parameters, simply quoting them or using
-- will make shellcheck stop warning, e.g.
set -- var1 var2 or
ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.