hackdaddy has asked for the wisdom of the Perl Monks concerning the following question:

Because my Perl utility script has external dependencies on Unix commands, how can I be sure that the Unix commands will be available in the location I expect them to be? How can I be sure that they will be the versions I expect? How can I be sure the Unix command is not an alias?
/bin/echo /bin/which /bin/df /bin/uname /bin/awk /bin/ls sqlplus grep find gtar
On the Windows platform, there is a standard Windows API for querying the machine's hardware and configuration. When scripting in a Unix environment, how does the programmer ensure standard results when using external Unix commands?