my $archive = "/some/dir/archive.tar.gz";

# Split the filename off of the directory using a regular expression
my ($dir, $filename) = $archive =~ m#^(.*)/([^/]+)$#;

# Switch in to the directory with the archive
chdir($dir) || die "Invalid path $dir\n";

# Extract the archive using 'tar'
system("tar","-xvzf",$filename);