use CGI;
use Archive::Tar;
use Compress::Zlib;

$tar=Archive::Tar->new();
$tar->add_files("my","list","of","files");
$gz=Compress::Zlib::memGzip($tar->write());

print "Content-type: application/x-gzip\r\n";
print header(-type => 'application/x-gzip');
print $gz;
[download]

You can use a Content-disposition header for the default filename:

print "Content-disposition: attachment; filename=foobar.tar.gz\n";
[download]



[ ar0n ]

open(TAR, "tar <options> |") or die "couldn't tar";
print while <TAR>;
[download]

2) The webservers I've used will let you trick the browser into thinking a file has a different name by treating the script as a directory. For example, if you have a script at "http://here.com/cgi/download.cgi", you could have the browser pop up with "thisfile.tar.gz" by showing the user the URL "http://here.com/cgi/download.cgi/thisfile.tar.gz". Also make sure you send the appropriate content-type header. Check your webserver docs and give it a shot, though your mileage may vary.

The first part of answering any problem is asking the full question:

• How often will the contents change?
• How many times will this be called?
• How many users?
• How large are the files?
• Is there any reason (from the questions above) that you can't just use a cron job to create tar files periodically, saving system power, and user time?

J. J. Horner
Linux, Perl, Apache, Stronghold, Unix
jhorner@knoxlug.org http://www.knoxlug.org/

I think there should be no problem, as your script can simply attach itself to tars output. There come some problems with that, too, as your download cannot be resumed, but I guess you can live with that. Here is some code how I would try it - I've never done this myself, so a look into perlipc could maybe help you a bit more.

  $blocksize = 4096;

  open( BACKUP, "tar cz $directory |" ) or die "can't fork tar: $!\n";
  binmode BACKUP; # just to be on the safe side

  do {  
    $read = read( BACKUP, $data, $blocksize ) or die "can't read: $!\n
+";
    if ($read) {
      print $data;
    };
  } while $read;

  close BACKUP;
[download]

As with your second problem, the "wrong" filename, you can either instruct your webserver to treat your script as a directory and everything following the script name as a parameter to your script (look in the Apache documentation, as it's been a long time since I did this, I guess under SCRIPTEXEC), and issue a redirect from your script (if called without parameters) to an URL with the parameters :

  http://invalid.com/cgi-bin/backup.cgi
  -> http://invalid.com/cgi-bin/backup.cgi/backup.tar.gz
[download]