use Archive::Tar;

# using the cli utility gunzip 
# -c causes the file to be 'cat'ed
open F, "gunzip -c $filename |";

my $tar = Archive::Tar->new(*F);

##</code><code>##

use Archive::Tar;

# using the cli utility compress 
# -c causes the file to be 'cat'ed
open F, "uncompress -c $filename |";
# or use 
# open F, "zcat -c $filename |";

my $tar = Archive::Tar->new(*F);