758
tar -vczfx123 ought to do it
(imgs.xkcd.com)
img title="I don't know what's worse--the fact that after 15 years of using tar I still can't keep the flags straight, or that after 15 years of technological advancement I'm still mucking with tar flags that were 15 years old when I started."
Only works for tar.gz. Remember there's also tar.xz, tar.bz, tar.bz2 and half have their own extractor flag. FUN. It's usually J.
The post only calls for "a valid tar command", not that it has to work for any specific circumstance.
xaf(extract a file) auto-detects the format.Extract Any File
Extract All Files
I don't remember the last time I had to worry about the compression. I simply run
tar xf myfile.tar.whateverand it works every time.