[lightbulbjim]

You can just call ‘tar xvf’ and it will detect the compression format.

[necovek]

My question was about how "tar xvzf" should be called "untar".

Your reply might still make sense (i.e. untar could automagically figure it out), but I was highlighting how tar/untar today also means (de)compressing that tar archive using many different compression formats.

[nicoburns]

It should probably be `untar --format gzip`