Look at \Q and \E in perlre. 
$string = '(.asdf[0-9])$';
$foo = '(.asdf[0-9])$';
if ( $foo =~ m/$string/ ) {
    print "won't work\n";
}
if ( $foo =~ m/\Q$string\E/ ) {
    print "will work\n";
}

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In reply to Re: Sanitizing strings as regexes by mr_mischief
in thread Sanitizing strings as regexes by carenas2

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