Ingo Karkat
2013-04-29 19:35:36
In GVIM, you can customize the tab labels with the 'guitablabel' option.
In terminal Vim; there's no 'guitablabel' equivalent; one has to render the entire 'tabline'. Fortunately, the Vim help has an example which delegates the label rendering to a separate function, so re-using your custom function is pretty easy.
The help pages for the mentioned options link to examples; you probably have to use fnamemodify() to canonicalize all buffers' paths to full absolute paths, find the common base directory, and then strip that off the paths.
On the other hand, if it's okay for you to :cd to the base directory, you'll get that kind of tab label pretty much out-of-the-box.