use strict;
my $str = '<img style="cursor:pointer;" onclick="S("lightfly")" src="chat/smiles/smiles_lightfly.gif"> <img style="cursor:pointer;" onclick="S("laugh")" src="chat/smiles/smiles_laugh.gif">';
my $regex = qr/<img(.*?)\/(.*?)\/(.*?)\.gif">/mp;
my $subst = ':$3:';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html