Comment by chihuahua - Hacker Neue

chihuahua Dec 12, 2025 parent

I seem to remember "tar xvf filename.tar" from the 1990s, I'll try that out. If I'm wrong, I'll be dead before I even notice anything. That's better than dying of cancer or Alzheimer's.

anyfoo Dec 12, 2025

I still do that at least once a week. Along with "tar xzpvf" or more complex invocations like:

    tar cvf - -C /foo/bar baz | zstd > foo.tar.zstd

tharkun__ Dec 12, 2025

    tar zxvf

Is burnt into my brain. One of my earliest Linux command line experience required untaring zipped tars.

So yeah that xkcd is "not funny" to me in that sense. Of course I couldn't tell you pretty much any other use without a man page.

necovek Dec 12, 2025

z requires it's compressed with gzip and is likely a GNU extension too (it was j for bzip2 iirc). It's also important to keep f the last because it is parametrized and a filename should follow.

So I'd always go with c (create) instead of x (extract), as the latter assumes an existing tar file (zx or xz even a gzipped tar file too; not sure if it's smart enough to autodetect compress-ed .Z files vs .gz either): with create, higher chances of survival in that xkcd.

thaumasiotes Dec 12, 2025

    tar xvzf file.name

is always a valid command, whether file.name exists or not. When the file doesn't exist, tar will exit with status '2', apparently, but that has no bearing on the validity of the command.

Compare these two logs:

    $ tar xvzf read.me
    tar (child): read.me: Cannot open: No such file or directory
    tar (child): Error is not recoverable: exiting now
    tar: Child returned status 2
    tar: Error is not recoverable: exiting now

    $ tar extract read.me
    tar: invalid option -- 'e'
    Try 'tar --help' or 'tar --usage' for more information.

Do you really not understand the difference between "you told me to do something, but I can't" and "you just spouted some meaningless gibberish"?

necovek Dec 12, 2025

The GGP set the benchmark at "returns exit code 0" (for "--help"), and even with XKCD, the term in use is "valid command" which can be interpreted either way.

The rest of your slight is unneccessary, but that's your choice to be nasty.

tharkun__ Dec 14, 2025

Like I said, I was operating on a lot of zipped tars. Not sure what you are replying about.

The other commenter already mentioned that the xkcd just said "valid", not return 0 (which to be fair is what the original non xkcd required so I guess fair on the mixup)

necovek Dec 16, 2025

Oh, just funny mental gymnastics if we are aiming for survival in 10 seconds with a valid, exit code 0 tar command. :)

As tar is a POSIX (ISO standard for "portable operating system interfaces") utility, I am also highlighting what might get us killed as all of us are mostly used to GNU systems with all the GNU extensions (think also bash commands in scripts vs pure sh too).

No offense intended, just the hackers' chat.

tharkun__ Dec 16, 2025

Hehe fair enough in that case. Tho nothing said it had to work on a tar from like 1979 ;)

To me at least POSIX is dead. It's what Windows (before WSL) supported with its POSIX subsystem so it could say it was compatible but of course it was entirely unusable.

    Initial release July 27, 1993; 32 years ago

Like, POSIX: Take the cross section of all the most obscure UNICES out there and declare that you're a UNIX as long as you support that ;)

And yeah I use a Mac at work so a bunch of things I was used to "all my life" so to speak don't work. And they didn't work on AIX either. But that's why you install a sane toolchain (GNU ;) ).

Like sure I was actually building a memory compactification algorithm for MINIX with the vi that comes with MINIX. Which is like some super old version of it that can't do like anything you'd be used to from a VIM. It works. But it's not nice. That's like literally the one time I was using hjkl instead of arrow keys.

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