Old XKCD, still relevant ( lemmy.dbzer0.com ) Englisch

arc , vor 2 Monaten

I know tar zxf and xjf off by heart. I probably do 100x as many extracts as creates. Tar is a stupidly antiquated command though.

flying_sheep , vor 2 Monaten

Why remember/include the algorithm? Tar can infer that. It's just bsdtar xf filename.* for everything. (bsdtar handles .zip as well)

Samsy , vor 2 Monaten

The bomb said tar.

flying_sheep , vor 2 Monaten

Yes, and tar works the same, it just doesn't handle zip files.

And even if we're pedantic: bsdtar is Arch Linux’ executable name for a port of the tar command that is shipped by BSDs, so it's also tar.

doggle , vor 2 Monaten

tar --version

You're welcome

bitwaba , vor 2 Monaten

I'd have gone with tar --help

flying_sheep , vor 2 Monaten

It's insane that this isn't consistent.

Any combination of -h, -? and --help exists

FMEEE , vor 2 Monaten

So would have been 1:4

zaphod , vor 2 Monaten

Never seen -?, it's either -h, --help, or -help for programs that just want to be different.

flying_sheep , vor 2 Monaten

One example for it is … tar!

https://www.man7.org/linux/man-pages/man1/tar.1.html

zaphod , vor 2 Monaten

I suppose I usually try -h and if that doesn't work I try the long version or the man page.

Aganim , vor 2 Monaten

Sorry, the bomb was running MacOS. Your command was not valid and you've doomed us all.

Andrew15_5 , vor 2 Monaten

It's literally there at the bottom.

What isn't valid is MacOS, it's macOS now.

EuroNutellaMan , vor 2 Monaten

I memorized tar -cavf file.tar.bz2 directory/* and tar -xavf file.tar.bz2

gandalf_der_12te , vor 2 Monaten

tar -cf file.tar directory/

gandalf_der_12te , vor 2 Monaten

that was 8 seconds.
close one, i saved us all

fonji , vor 2 Monaten

How do you know directory exists? 😨

gandalf_der_12te , vor einem Monat

shit

tisktisk , vor 2 Monaten

tar -xvf or we all kill

lseif , vor 2 Monaten

shouldnt there be a filename argument ?

Enfors , vor 2 Monaten

Yes. However, if you had skipped the -f, it would have been valid. Without the filename argument, it assumes it should extract from the tape drive (TAR = Tape ARchive). The tape device is probably something like /dev/rmt0, but you don't need to specify that. Using the -f is technically an exception which means "instead of extracting from the tape like you'd normally do, pretend that this file is the tape device instead."

barsoap , vor 2 Monaten (Bearbeitet vor 2 Monaten)

GNU tar, at least a modern one, that is the one that happens to come with my system, won't try to read from /dev but stdin and then complain that it's a terminal and refuse.

Quoth POSIX on the f flag:

Use the first file operand [...] as the name of the archive instead of the system-dependent default.

That is GNU is compliant, here, the default is system-dependent. f - is required to be stdin, though, so you can bunzip2 foo.tar.bz2 | tar xf - or such in a portable manner, don't have to rely on tar having a z option (which is nonstandard) or it auto-detecting compression (even more nonstandard). What is not standard either is tar -x: Tar doesn't take leading hyphens. Tar is one of those programs so old its command line syntax got standardised before command line syntax standards were established. OTOH it's not nearly as bad as dd, you can interpret how tar does things in the same way as git pull: It's a subcommand, not a flag.

tisktisk , vor einem Monat

"one of those programs so old its...syntax got standardized before command line syntax standards were established."
--This is wild to learn, but also confusing. How does tar not take leading hyphens, but I've only ever used it as such without error of any kind? Not even bragging I've been doing that for 10+ years too lol

barsoap , vor einem Monat (Bearbeitet vor einem Monat)

Hmm. Actually you prompted me to dig a bit deeper: tar goes all the back to Version 7 UNIX, 1979, but the command line syntax is shared with tap, included in Version 1, man page dated to 1971-11-03. Development of C started 1972. Might've been written in B, you'd have to unearth a source archive I bet it's around somewhere. But anyway if you look through the other Version 1 commands a lot of them don't take hyphen commands, ls does, e.g. rm doesn't on account of only taking file names as arguments.

dd is actually younger, Version 5, 1974, the syntax apparantly comes from IBM's JCL.

Admittedly, that's all before my time.

Both BSD and GNU tar take hyphens, I don't really have any experience with anything else but a short stint with Solaris in the early 2000s (very emphatically before Sun got gobbled up by Oracle) and I don't remember hyphens tripping me up. Much unlike killall. And I'm apparently not alone in that.

tisktisk , vor einem Monat

I definitely still killed us all, but at the same time how are you supposed to know any of the filenames if none are given from the comic?
I guess my real answer is to 'tar -xvf' then hit tab with hopes of decent file completion functionality lol

lseif , vor einem Monat

tar -czf $(ls | head -n1) if we dont trust globs

or run find in /bin or something

recapitated , vor 2 Monaten

ya blew it kid

umbraroze , vor 2 Monaten

Actually this reminds me, what is the deal with tar command recommendations to use or not use dash? I know GNU tar accepts both (e.g.) tar xvf file.tar and tar -xvf file.tar, but at some points people were like "NO! Don't use the dash! It's going to maybe cause issues somewhere, who knows!" and I was like "OK". Something to do with people up designing the Unix specs?

debil , vor 2 Monaten

No idea, but with tar I never use dashes. Just tar xf away.

vox , vor 2 Monaten

idk if it's optional why bother typing it

lseif , vor 2 Monaten

personally, it is a little easier to read, especially in a script. and its more consistent with other commands

ben , vor 2 Monaten

I didn't even know the dash was optional. I guess you learn something new everyday.

MehBlah , vor 2 Monaten

I still use it though. Its how I learned it all those years ago and its ingrained as muscle memory when typing the command.

barsoap , vor 2 Monaten

POSIX. POSIX didn't get designed but documented behaviour that was portable between different UNIX flavours and was then declared a standard.

If you're annoyed by it just consider the xvf in tar xvf to be a subcommand as pull is in git pull. Tar simply has a fancy subcommand syntax. At least it's not dd.

llothar , vor 2 Monaten

tar -xzf stands for tar eXtract Ze Filez

kshade , vor 2 Monaten

I like tar xaf (eXtract All Files) better.

01101000_01101001 , vor 2 Monaten

You can skip the z; tar is smart enough to figure it out on its own

samus12345 , vor 2 Monaten

I'd like to know if there are any XKCDs that are no longer relevant.

xorollo , vor 2 Monaten

I'd like to know if there's an XKCD about an XKCD that's no longer relevant.

DerisionConsulting , vor 2 Monaten

There are some that were wrong to begin with, I remember 622 bothering me.
https://xkcd.com/622/

But it could also just be that in the comic, the professor is wrong.

Faresh , vor 2 Monaten (Bearbeitet vor 2 Monaten)

This one, if by unix he also means modern linux systems. Nowadays you can simply use tar xf my-file.tar.whatever and it should work on most linux systems (it worked on every modern linux system I've tried and every compressed tar file I've tried). I don't think it is hard to remember the xf part.

bradorsomething , vor 2 Monaten

| man tar

faerbit , vor 2 Monaten

This is a valid man command, but not a tar command

bradorsomething , vor 2 Monaten

I’ll use the man page to find a command; it said 10 seconds, not 1 try!

Lime66 , vor 2 Monaten

tar --version

Oderus , vor 2 Monaten

Read my mind. :D

MyFairJulia , vor 2 Monaten

Remember: Just tell tar to Xtract Z File.

holgersson , vor 2 Monaten

Xtract gZipped File

elrik , vor 2 Monaten

How does it verify the command is valid? Does it run what I enter?

If so, just give it an infinite loop followed by some attempt at a tar command:

while true; do :; done; tar -xyz

velvetThunder , vor 2 Monaten

Next time I build a bomb I let the timer continue while the command is running.

Voroxpete , vor 2 Monaten

Yeah, what kind of idiot doesn't parallelize their timer function.

mlg , vor 2 Monaten

Blue Team: "Okay everyone let's make sure this is absolutely the correct input"

Red Team: "Lmao lets try this 90mb list of bash command injection patterns"

lseif , vor 2 Monaten

i assume its looking for exit code of 0

lseif , vor 2 Monaten

echo || tar -xfzhd

kameecoding , vor 2 Monaten

I do tax -xvf filename

WhiskyTangoFoxtrot , vor 2 Monaten

tax

Boom.

kameecoding , vor 2 Monaten

ah fuck, didn't even notice

justme , vor 2 Monaten

quod erat demonstrandum :D

Karyoplasma , vor 2 Monaten

or quod errat demonstrator, both fit.

gandalf_der_12te , vor 2 Monaten

quod erat expectandum?

justme , vor 2 Monaten

Quot expocto patronum!

Bosht , vor 2 Monaten

Christ this comment chain is perfect lmfao

DogWater , vor 2 Monaten

I like the way you pointed that out lmao

Voroxpete , vor 2 Monaten

.... aaaaaand you've killed us all.

Steamymoomilk , vor 2 Monaten

I just use ouch

JackGreenEarth , vor 2 Monaten

tar -h

woelkchen , vor 2 Monaten

Just tar, no arguments. Does nothing, still a valid command, no?

foobaz , vor 2 Monaten

Exit code 2 -> boom

rrconkle , vor 2 Monaten

tar: You must specify one of the '-Acdtrux', '--delete' or '--test-label' options
Try 'tar --help' or 'tar --usage' for more information.

doctorzeromd , vor 2 Monaten

Boom. tar --help for anyone wondering