from, perlretut
If $pattern won't be changing over the lifetime of the script, we can 
+add the "//o" modifier, which directs Perl to
       only perform variable substitutions once:

           #!/usr/bin/perl
           #    Improved simple_grep
           $regexp = shift;
           while (<>) {
               print if /$regexp/o;  # a good deal faster
           }

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In reply to Re: A regular expression (or regex) by suhailck
in thread A regular expression (or regex) by anakin30

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