I can certainly understand the impulse to something like this, but as other posters pointed out, your case statement is incomplete, and will continue to become

I can certainly understand the impulse to something like this, but as other posters pointed out, your case statement is incomplete, and will continue to become more so as new tools become available. Personally, I consciously avoid using the internal decompression features of tar, both out of habit and to avoid unexpected results. As such, I generally use command lines like: bunzip2 -c <tar.bz2 file> |tar xvf - instead of relying on tar xvjf I don't see it as wrong or bad to use tar's decompression features, it's more about my own preferences and experience. Being able to perform similar actions in multiple ways is one of the things I've always appreciated about the shell and the Unix/GNU userland.