$ echo 'package Tom;' > foo.pl

$ chmod u+x foo.pl

$ ./foo.pl              
package: not found
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This is where splain comes in handy.

$ ./foo.pl 2>&1 | splain
package: not found (#1)
    (A) You've accidentally run your script through the
    Bourne shell instead of Perl.  Check the #! line, or
    manually feed your script into Perl yourself.
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Your mistake in posting was to say "my code looks something like this, it gives some errors" and then go into a long tangent about what you THINK might be causing the errors. Much better is to say "here's the exact code, here is what I expected it to do, and here is the exact error I got." Smart Questions HOWTO.

(The mystery of how somebody who doesn't understand that #! is parsed by the shell got a job adminning 800 Linux boxes is left as an exercise to the reader.)