use Compress::Zlib;

my $fil = shift || die ("need compressed file, stopped");

die "$fil not a gz'd file, stopped" 
unless (($fil =~ /.gz$/) || ($fil =~ /.Z$/));

(my $rootfil = $fil) =~ s/.gz$//;

open OOTFIL, ">$rootfil" or die ("cannot open file for gunzip");

binmode OOTFIL or die ("cannot binmode $rootfil");

$gz = gzopen($fil, "rb") or die ("can't open $fil, $gzerrno, stopped");

my $buffer;

print OOTFIL $buffer while $gz->gzread($buffer) > 0;

die "Error reading from file $file: $gzerrno\n" if $gzerrno != Z_STREAM_END;

$gz->gzclose();

close(OOTFIL);