On handy way to create and manage files on your *nix servers it to use tar files to store and back up your data. One thing that you might find you need, however, is a way to use PHP to create a dynamic archive of some files - either for downloads or backups - and this new article from DevShed can show you how.

They introduce you to the Archive_Tar class (a part of PEAR) to create dynamic GZIP, BZIP, and TAR archives. It even allows you to add files to an archive that already exists, making the update and recompression a snap.

It really is quite a fun little tool, especially if you've been looking for a way to create an archive/package on the fly of files from your site. I could really see a site, something like SourceForge or Freshmeat, using this kind of functionality to allow people to create revisions and packages from the sets of files that are sitting in their FTP directory.