I'm confused with a negative lookahead. Here's some example code. I want it to match on $needs and to not match on $has. The examples 3 and 4 are only as a reference to a fixed string, but I basically want ^($start(.*?))(?!$end)$. Any ideas?

#!/usr/bin/perl
use strict;
use warnings;

my $start = "log4j.rootLogger=";
my $startlong = "log4j.rootLogger=INFO, FILE";
my $end = ", SYSLOG";

my $needs = 'log4j.rootLogger=INFO, FILE';
my $has = $needs . ', SYSLOG';

print "needs_matched $needs\n" if $needs =~ /^($start(\w+(,\s)?)+)(?!$
+end)$/;
print "has_matched $has\n" if $has =~ /^($start(\w+(,\s)?)+)(?!$end)$/
+;
print "needs_matched $needs\n" if $needs =~ /^(log4j.rootLogger=INFO, 
+FILE)(?!, SYSLOG)$/;
print "has_matched $has\n" if $has =~ /^(log4j.rootLogger=INFO, FILE)(
+?!, SYSLOG)$/;
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