Why do scripts define common commands in variables?

Question

I see this all the time at my place of work:

#!/bin/sh

.....

CAT=/usr/bin/cat                                  # An alias for cat
MAIL=/usr/bin/mail                                # An alias for mail
WC=/usr/bin/wc                                    # An alias for word count
GREP=/usr/bin/grep                                # An alias for grep
DIRNAME=/usr/bin/dirname                          # An alias for dirname
RM=/usr/bin/rm                                    # An alias for rm
MV=/usr/bin/mv                                    # An alias for mv

.....

Is it just my company that does this? Is there a reason why you would want to spell out where these extremely common commands are? Why would I want $CAT to refer to /usr/bin/cat when cat already refers to /usr/bin/cat? Am I missing something? It seems like its needlessly redundant.

Answer 1

Using the full pathname ensures that the script operates correctly even if it's run by a user who customizes their PATH environment variable so that it finds different versions of these commands than the script expects.

Using variables simplifies writing the script, so you don't have to write the full pathname of a command each time it appears in the script.