while (args here) {
    $new_dir = code to figure out correct path...
    $file = code to determine file to work on...
    $ENV{'PATH'} .= ":/home/mysite/documents/daily/$new_dir";
    system("gzip $file") == 0 or die "can't gzip file";
    $ENV{'PATH'} = gets reset to original path here.
    }