A .tar archive is basically only the files cat’ed together, with a header and index added, right?
And a .tar.gz takes forever to modify, because it needs to first extract the .tar.
So why is there no archive format that just cat’es the compressed files together?
Hey, you can add to a tarball without extracting it! Maybe that’s what you’re actually asking?
Anyway, in case it wasn’t, here’s a bit more answer:
A .tar.gz is a file that used to be .tar and was then compressed by gzip.
A .gz.tar is a file that used to be .gz and was was made into a tarball.
I cannot really imagine why someone would want to turn a .gz file into a tarball. Kind of in order to save it on an actual tape drive, maybe? But then it wouldn’t be a tarball. It would be just ones and zeroes physically saved on a tape.
You can save .tar.gz files to actual tapes. As you said, it’s just one and zeros.
Of course, and that is done very often. But why would you want to save a .gz.tar file on a tape?