Config files : Incomplete option handling

In this case, sh and dash are POSIX-compliant shells where exec options (-c, -l, -a) are not defined.

POSIX is a family of standards, specified by the IEEE, to clarify and make uniform the application programming interfaces and ancillary issues, such as command line shell utilities provided by Unix operating systems.

exec is a command that executes a Shell command without creating a new process. Instead, it replaces the currently open Shell operation.