use strict;
use warnings;

use Compress::Zlib;

# Set up what we want to match.
#
our $reg1 = "Joe Sinclair";
our $reg2 = "Bill Halburg";
our $rxNames = qr{(?:$reg1|$reg2)}

# Open compressed log file.
#
our $logFile = "file.gz";
our $gzInput = gzopen($logFile, "rb")
   or die "gzopen: $gzerrno\n";

# Read line by line into $_ counting bytes read.
#
our $bytesRead;
while($bytesRead = $gzInput->gzreadline($_))
{
    # Print if it matches.
    #
    print if /$rxNames/;
}

# Check that we have read to the end. Close
# file.
#
die "Incomplete read: $gzerrno\n" unless
   $gzerrno == Z_STREAM_END;
$gzInput->close();
[download]

I have not tested this but I have adapted it from a script doing somthing similar.

Cheers,

JohnGG