You need a regular expression in your if-test. Start by doing:

   perldoc perl
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at a command prompt. You'll notice if you page down a little that there are these 2 perldocs listed for regular expressions:

   perlre              Perl regular expressions, the rest of the story
   perlreref           Perl regular expressions quick reference
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So, if you want to read the 1st one, you would do

   perldoc perlre
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at a command prompt. The 1st response to your question gave you a regular expression to try. Read the perldocs, try a regular expression, and post back if you still have problems.

HTH.