use strict;
my $str = '@font-face {
src: url(\'../some-font.eot?v=4.6.3\');
}';
my $regex = qr/eot\?[^'"]+/p;
my $subst = 'eot';
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