Here is where your problem lies (reformatted for readability):

foreach $line (@lines)
{
    if($line =~ /test/)
    { 
        $1 =~ s/<p>//gi; 
        print $1;
    }

    if($line =~ /meta/)
    {
        print "$line"
    };
}
[download]

You're looping through all of the lines of content. You test each line to see if it contains the sequence 'test'. If so, you perform a substitution on $1, which contains the first capture of the most recent successful regular expression. Unfortunately, there have been no captures. You print the modified variable, which is doubly-odd, as it's a read-only value. If the line contains the sequence 'meta', you print it with no substitutions.

It's unclear what you're trying to do, unless you just want to strip out opening paragraph tags. That might be:

if ($line =~ /test/)
{
    $line =~ s/<p>//g;
    print $line;
}
[download]

I think you'll have to give an example of what might be in $line before you scrub it and an example of the scrubbed version, though.