-ain place of
(or "In dash, ... is not supported." when using
#!/bin/sh if [ -a file.txt ] then echo "file.txt exists" fi
#!/bin/sh if [ -e file.txt ] then echo "file.txt exists" fi
-a was used in some shells to check for the existence of a file, but the POSIX standard and better supported equivalent is
If you only intend to target shells that supports this feature, you can change the shebang to a shell that guarantees support, or ignore this warning.
You can use
# shellcheck disable=SC3000-SC4000 to ignore all such compatibility warnings.
ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.