/dev/chat

8:45 AM

Is there a meta post which describes how one should learn linux?

9:06 AM

@ahorn Well probably no but I'm no expert on meta site. This could be an idea however this is very opinion based and not really answerable.

Rui F Ribeiro

@Kiwy Salut.

Kiwy

9:31 AM

@RuiFRibeiro bom dia

Rui F Ribeiro

10:06 AM

@Kiwy ça va?

Faheem Mitha

10:26 AM

@ahorn There is no such prescription.

And "learn linux" isn't a well-defined procedure, anyway.

Rui F Ribeiro

11:14 AM

@FaheemMitha I disagree learning Linux is not a well defined procedure. You just take a pill or ask for a spell from a Linux necromancer in any Internet board ;) We also have revive spells for hard disks and USB media. ;)

Faheem Mitha

@RuiFRibeiro Please introduce me to your friendly neighborhood Linux necromancer.

Archemar

I think I know the name of the most famous Linux necromancer,

his name is Kali, Kali Linux.

αғsнιη

11:31 AM

Hi

anyone is using GNU 'ls' v8.28?

Stephen Kitt

@αғsнιη specifically, or “or newer”? I’ve got 8.30

αғsнιη

can you create a file named with 'afile with null'$'\0'' character' and then do \ls afile* and tell us if it correctly shows $'\0' when doing \ls ?

please

Stephen Kitt

@αғsнιη yes, it does

αғsнιη

OK, so seems it's issue with 8.28 specific

thank you Sir

Stephen Kitt

How did you create your file?

terdon

11:43 AM

and what is the issue?

αғsнιη

touch 'a file with null'$'\0'' character'

and my below ls doesn't show '$'\0'' in filename

Stephen Kitt

@αғsнιη that’s because your filename doesn’t have null in it

Note that POSIX file names can’t contain null...

terdon

@StephenKitt Thank you. I was wondering what you meant when you said your ls was showing a NULL in the file name.

αғsнιη

$'\0' doesn't print null character you mean?

Stephen Kitt

@αғsнιη it does, but touch creates a file named “afile with null”.

I thought you were talking about a file with all those characters in its name, escaped...

So touch "'afile with null'$'\0'' character'" works, and creates a file whose name contains all those characters.

terdon

11:47 AM

27

A: Newlines in filenames

I've never seen a file name with a newline other than ones deliberately created to test applications that manipulate file names. File names containing newlines can appear because: Some bug or user error (e.g. a bad copy-paste) resulted in an unintended file name. Some filesystem corruption affe...

Stephen Kitt

But touch 'afile with null'$'\0'' character' stops at the null character.

terdon

> The characters composing the name may be selected from the set of all character values excluding the slash character and the null byte.

Kiwy

@RuiFRibeiro ça va très bien et toi ?

αғsнιη

@StephenKitt but I can crate any other file with newline or tabs or any special character with C-style escaping $''

terdon

@StephenKitt It's actually stripped. At least on my bash: touch 'a'$'\0''b will just create ab. So it doesn't stop at the NULL, it just ignores it.

Kiwy

11:49 AM

My Portuguese is really limited

terdon

@αғsнιη Yes. The issue is that file names cannot contain NULL or /

Any other character is fine.

αғsнιη

@terdon aha

Kiwy

Newline in filename is an aberration of nature . It should never have been a possibility

Stephen Kitt

@terdon hmm, weird, in my test it stops at the null (which makes sense)

terdon

@StephenKitt It does, yes. But not what I'm seeing:

terdon@tpad foo $ bash --version
GNU bash, version 5.0.2(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2019 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
terdon@tpad foo $ touch  'a'$'\0''b'
terdon@tpad foo $ ls
ab

αғsнιη

11:50 AM

mine also ignore NULL charater

Stephen Kitt

@terdon OK, with Bash 4.4.23(1) and coreutils 8.30 I get a only.

terdon

Hang on though, this can't depend on the bash version. Bash just expands it correctly. Presumably, it is being stripped by whatever filesystem function touch calls to create the file.

$ touch --version
touch (GNU coreutils) 8.31

Stephen Kitt

ext4 here

terdon

same here

αғsнιη

I'm on WSL, touch version is GNU 8.28

Stephen Kitt

11:52 AM

@terdon yes, it can — strace touch ... shows that touch is execed with a only, here.

terdon

@StephenKitt Really? And so does set -x, right?

Stephen Kitt

oh wait I’m in zsh

terdon

Ah-ha!

(the band)

Kiwy

I wish that initiative was already true dwheeler.com/essays/fixing-unix-linux-filenames.html

Stephen Kitt

Yup, bash creates ab

So... zsh v. bash, round 3896

terdon

11:55 AM

@StephenKitt Um. No? Stripping illegal characters makes more sense to me than stopping at them.

I mean, yes, OK, zsh is indeed better and I need to learn to use it at some point, but this doesn't seem like a point in its favor.

Stephen Kitt

@terdon yes, I’m not saying zsh is right, I’m saying it’s another of those obscure differences in behaviour

terdon

Ah, sorry, I read that as "zsh vs bash 3896 to naught" or something.

Interestingly, dash also strips it:

scratch that, looks like dash doesn't even get $'\0'

But ksh creates ab

And yep, zsh creates a for me too.

Kiwy

@terdon @StephenKitt Hello both of you. I think no command should assume thing you didn't meant, touch should just output an error with illegal caracter

Stephen Kitt

@Kiwy touch doesn’t get the illegal character.

Kiwy

@StephenKitt then bash shouldn't strip it :D

Stephen Kitt

12:00 PM

@Kiwy think about what the null character means in argv...

Kiwy

@StephenKitt Does it mean end of argument ? if so then it's a correct behaviour I guess

Stephen Kitt

@Kiwy yes, it does; which behaviour? ;-)

Kiwy

however I feel like those filename with fancy characters should have been illegal years ago.
@StephenKitt well not passing null string to touch argument

Stephen Kitt

@Kiwy but we’ve been discussing two different approaches to that

Kiwy

well I miss something :D

if null character is suppose to mean end of arguments it should just not send argument after and send those before to a command, however null isn't really printable which could lead to lots of issue (specially when some copy/paste happen)...
Huuu.... that's puzzling

terdon

12:24 PM

@Kiwy But it's a perfectly valid character. It's only an issue if you try to use it as part of a file name. As part of a string, it's fine:

$ printf 'a\0b' | od -a
0000000   a nul   b
0000003

But:

$ echo $(printf 'a\0b')
bash: warning: command substitution: ignored null byte in input
ab

Kiwy

💻:~:🦄 echo $(printf 'a\0b' | od -a)
0000000 a nul b 0000003
💻:~:🦄 echo $(printf 'a\0b')
bash: warning: command substitution: ignored null byte in input
ab

Behaviour is varying depending on the context => that sucks

it should be one or the other but it should not be a bit of both, we're not living in Hannah Montana's world and we can't get the best of both world :D

if you don't have the reference (it's OK and you should not have it anyway)

Also my prompt does have a computer and a unicorn emoji in it I know. When I go root I even have a 🔥 emoji...

Rui F Ribeiro

1:09 PM

@Kiwy I had 9 years of french as a pre-teen....can folllow it pretty well, but have not tried to use it for decades ;)

@Kiwy ça va bien merci

Kiwy

@RuiFRibeiro I have to confess I never learned Portuguese in any way...

Rui F Ribeiro

@Kiwy In my parents time French was the language for the Europe, at least from our point of view...then it shifted for English when I was a kid.

Kiwy

And I I had Spanish lessons, my level is limited to : "Holà que tal ?"

Both are really nice languages . I love them both (English and French), but I'm pretty sure each language has its specificities that makes it unique and enjoyable .

Rui F Ribeiro

@Kiwy Spanish served me for a while for computer initiation, but then English has served me quite well throughout the years.

derobert

5:35 PM

Tilde expansion, why oh why do you have to come after variable expansion?

grumble getent passwd "$user" | cut -d: -f6 grumble

Interesting, Google for that line lead me to a question here where I got to point out a security flaw in an answer :-D

Faheem Mitha

5:58 PM

@derobert Upgrading now. Hope I get to reboot. The installation made noises about my card not being supported by the nvidia driver, and said I should install the legacy driver instead. But apt won't install the legacy driver.

derobert

@FaheemMitha that's odd, why won't it install the legacy one?

sounds like you have something for an installation report, though

Faheem Mitha

@derobert reportbug installation-reports?

Here's what it looks like:

root@orwell:/home/faheem# apt-get install nvidia-legacy-390xx-driver
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
libdpkg-perl : Depends: perl:any

derobert

@FaheemMitha upgrade-reports is what the release update said

Faheem Mitha

@derobert Oh, sorry.

derobert

I'd try it again after the rest of the packages are upgraded, before rebooting. X is unlikely to work without it, unless you can switch to the open source drivers.

Faheem Mitha

6:05 PM

@derobert reportbug upgrade-reports isn't giving me a template. Not very helpful.

About halfway through a dist-upgrade now.

derobert

And soon, you'll get to have the fun of re-learning years of muscle memory to change su to su - :-/

Faheem Mitha

@derobert ?

derobert

without the -, Buster's su does nothing useful.

Faheem Mitha

6:30 PM

@derobert Syntax change? That's unusual.

Kusalananda

@derobert - is listed as deprecated and equivalent to -l in the OpenBSD manual.

-l does a full login.

derobert

su used to be useful, in that it'd set up some things like a full login (e.g., PATH), but leave others alone (like CWD). They made it no longer useful (e.g., no longer sets up PATH). su - / su -l / su --login of course winds up with CWD set to ~root

Faheem Mitha

@derobert I didn't use it enough to notice. Recently, at least.

Sounds like someone should have a word with them.

derobert

It's because Debian switched to a different su implementation, apparently.

You should have gotten a NEWS entry from apt-listchanges

Faheem Mitha

@derobert Oh

Faheem Mitha

7:01 PM

There are an awful lot of packages on my system I have no idea of the purpose of.

news.ycombinator.com/item?id=14579080

terdon

@derobert I don't think I've used su since I began using systems with sudo by default.

derobert

@terdon A lot of my workstations didn't used to have sudo set up to allow unrestricted root. (Now, they pretty much all do, because that change is annoying).

terdon

7:19 PM

@derobert I think I only discovered sudo when I first tried Ubuntu. So my years of RH, Fedora, SuSe and openSuSe were all su-based.

I just don't find myself using su anymore at all.

Oh and Mandrake! I had a few years of Mandrake. I forgot about that.

Faheem Mitha

8:03 PM

@derobert Do I need to do anything for EFI on upgrade?

derobert

@FaheemMitha shouldn't have to do anything special

Faheem Mitha

@derobert Ok. I guess I'll try doing a reboot now. I hope I can get back up. I installed the legacy Nvidia driver after dist-upgrade.

derobert

... and he was never seen again :-(

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