Shuttleworth: Unity shell will be default desktop in Ubuntu 11.04 (ars technica)

What we need to fix these problems is file tagging via extended attributes. In addition to the 'canonical' file path each file could have a tag cloud of simple text labels, which might if well integrated into a UI come to replace hierarchies for most people's organizational needs.

I was looking around the other day for this because I wanted to start tagging images that are not always JPEGs and I figured someone must, by now, have developed a scheme for using extended attributes for file tagging. What I have found so far is that nothing for this is published anywhere, even if some application or other may implement it, and there's certainly no common standard.

On a *nix system a hard link acts a lot like a tag: One or more names is associated with a file. The down side to hard links is that adding a lot of them, like 20 or more, for a single file purely for the purpose of 'tagging' it becomes a management nightmare. Extended attributes would work nicely for simple label tagging, though it would be nicer if tags could be typed so that dates (date taken, etc) could be stored this way as well.

If file tools knew about tags in extended attributes then it would be a simple matter to add a few to any file and have a VFS which lets me see one directory per tag on any file on the system and drill down to specific files. Some indexing would be required for that, naturally, but even without it we could certainly all benefit from moving MP3 and JPEG tags into metadata where they belong, writing them back to the files only when we're ready to transfer across the network.