Fix ShellCheck warnings
This commit fixes ShellCheck warnings.
Also see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=981663 and https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1058658.
This commit fixes ShellCheck warnings.
Also see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=981663 and https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1058658.