Here's a simple modification to the example code that will show what the regex matched when you typed it in:

#!/usr/bin/perl
while(<>) {
     chomp; # chomp so this next output is pretty.
            # newlines aren't discarded when you <>
     print "\"$1\" was matched out of \"$_\"" if m/(your_pattern)/;
}
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Be sure to include the parenthesis around the entire regex that way it will save what it matches in $1.

Do recall that while the regex operators are greedy by default you can suffix them with ? and they'll go to nongreedy. An example:

#!/usr/bin/perl

while(<>) {
        chomp;
        print "\"$1\" was matched out of \"$_\"\n" if m/(\w{5}?)/;
}
[download]

This will match "mywor" out of "myword"

Have fun regexing.