@Gilles I've just retagged the last few copy Q's; the tag is now empty

only took ... 2 months? slow & steady :)

@JeffSchaller Bravo.

Hi

Is paranthesis concatenating the results of two commands?

(cat /etc/sudoers-backup; echo "%deployers ALL=(ALL) ALL") > /etc/sudoers

@overexchange The parens doesn't do any concatenation, but the output of the subshell will be the contents of /etc/sudoers-backup directly followed by the line %deployers ALL=(ALL) ALL.

So, yes. You will get concatenation since the commands in the subshell does concatenation in a sense.

... but the parenthesis will not "do concatenation".

I hope that was clear enough.

@Kusalananda when you say subshell, Does shell launch a child process(shell) to execute (cat /etc/sudoers-backup; echo "%deployers ALL=(ALL) ALL")?

and then send the result back to parent shell?

Yes. With (...) a child process may be launched. I suppose that this depends on the implementation of the shell, but I think that in most cases it will launch a new shell.

You may replace (...) with {... ;} to execute the commands in the current shell environment without launching a subshell.

{ cat /etc/sudoers-backup; echo "%deployers ALL=(ALL) ALL"; } >/etc/sudoers

The ; at the end, before }, is mandatory.

Hey @Kusalananda.

Apparently my city is having a flood related emergency. I didn't notice. I really should pay more attention.

@FaheemMitha Ouch.

I don't get out much.

@FaheemMitha I also saw there was a fatal collapse of a building because of it. I hope you're living somewhere slightly elevated.

@Kusalananda No, not really. But buildings collapse here all the time. It's not news.

@FaheemMitha Well, it's front-page news over here... dn.se/nyheter/varlden/manga-doda-hittade-efter-husras

@Kusalananda Your site doesn't like my ad blocker.

Anyway, it's India. Greedy, incompetent, and corrupt builders.

... plus climate change with flooding.

@Kusalananda True, that doesn't help. But properly constructed buildings don't collapse if there is a flood.

@FaheemMitha :-) Even the most well constructed building will collapse if its foundations are washed away.

@Kusalananda Well, ok. But I don't know if that was the case here. And buildings here collapse regularly for no reason.

@FaheemMitha I hear what you're saying.

Mods, there's a potential issue with Peter's comment on unix.stackexchange.com/questions/389383/…

Running this command as root may be destructive.

I flagged it too.

sda0?

I'm not say that doesn't make the unexplained comment dangerous--even if that doesn't work, someone might assume it's a bug and "fix" it before running the command, see a different error message, not understand it, and change it to sda1, etc. If the problem is mangled permissions with /dev (though not its entries) set world-writable, it may even give a false positive--that is, it's not more reliable than other methods. It seems like a joke, at best, and a potentially dangerous one.

But--at least on a GNU/Linux system--I don't think there's ever an sda0 in /dev. It's /dev/sda for the first "sd" disk, /dev/sda1 for the first partition on it.

(I've also flagged the comment, though.)

@Kusalananda @EliahKagan Regardless of how dangerous it is or isn't, it's also not useful. It does not ask for more information or suggest imrpovements. "Answers" should go in answers, not comments. IOW, it should be deleted even if it were perfectly safe.

Good point.

Does apt-get drop privileges under some circumstances? unix.stackexchange.com/questions/389833/…

@Kusalananda maybe related: aptosid.com/…

@JeffSchaller Sounds like it. Care to make a comment on the question?

@Kusalananda done and done :)

@Kusalananda BAM! Go golden hammer go!

(ref: unix.stackexchange.com/q/389837/117549)

I was going to write up an answer, since the OP claims to not understand the dupe

@JeffSchaller That's a dangerous badge to have! I reopened it. I'm also thinking on an answer. Sorry if I interrupted you.

@Kusalananda no worries! I saved my work off, but Stack also saved it; gave me a chance to correct a copy/paste brain-o before posting it.

@JeffSchaller Looks like it'll work too. +1

@JeffSchaller The only thing possibly missing is a test to make sure it's a directory...

I'm not usually one to snipe questions, and he didn't like the Dupe Q, and it's Friday afternoon so that means read-only at work :)

@Kusalananda good point; I'll add it. They claim a certain structure, but always nice to be safe

man, I'm going to have to stop answering. Soon I'll have 20k fake internet points and be a "Trusted User"

can't have that

@JeffSchaller Yes we can! :-)

@Kusalananda I suppose we might eventually :) It's actually a bit of a self-reminder that I have other cleanup I want to do (tags, wikis), and shouldn't be bothering answering questions that other people do just as well

@JeffSchaller You're doing good work.

@Kusalananda thank you; likewise!