Tests could easily be marked "skip" because the user doesn't want to run them in their environment, and in this common case the set of tests will be non-nil
and modify text to command function to support this.
Shell builtins fail the binary command lookup test which result in a
WARN. Audit commands which include shell builtins must use the form:
"/bin/sh -c 'sh-builtin arg'"
So they are executed properly. Additionally Go will fail to execute
commands involving shell builtins if they are not in the above format.
