lib/util.sh: extern (): use exec to ensure that the executed command is in fact external, and not a shell builtin or other type of non-function command. this also simplifies the code because any shell function for the command does not need to be unset.
lib/util.sh: extern (): use exec to ensure that the executed command is in fact external, and not a shell builtin or other type of non-function command. this also simplifies the code because any shell function for the command does not need to be unset.