Linux @lemmy.ml exu @feditown.com 1y ago

Documenting commands # or $ before sudo?

This might be a stupid question, but hear me out.
I regularly document steps to install various software for myself on my wiki
More recently, I managed to use different custom text in the source markdown to prepend # and $ automatically, so commands can be copied more easily while still clarifying if it should be run as a normal user or as root.

Run command as user

$ some cool command

Run command as root/superuser with sudo

# some dangerous command

I usually remove and sudo and use the # prefix. However, in some cases, the sudo actually does something different that needs to be highlighted. For example, I might use it to execute a command as the user www-data

sudo -u www-data cp /var/www/html/html1 /var/www/html/html2

I often use $ as a prefix, but # would also make sense.
How would you prefix that line?

28 comments

I don't work much with Linux systems these days, but I would vote for $ sudo over #. Two reasons:

It's easy to overlook the prompt. That part is basically "some characters before the actual command", so I don't normally pay attention to it.

# is also used for comments. I think it would be confusing to use the same character for two wildly different things.
- So $ sudo in general any time I need to run something as root?
  I'll have to think about that some more. I think I rather dislike "forcing" sudo on all commands as root.
  
  Ok, maybe I misunderstood your question. I though you were proposing # instead of $ sudo and I meant to say that being explicit is better.
I have a fairly opinionated stance on this. Except in your sudo example where you’re specifically using sudo for a reason, I document all commands as non-root, and do not instruct them to raise privs. Whether or not they have, want or need privs, and how they raise them, is their system not mine.

It’s not exactly user friendly, but I don’t like to encourage people to blindly copy & paste commands that raise privs. That should be a conscious decision where they stop and ask themselves if & why it’s necessary.
I dislike when documentations add sudo because what if I am root already or what if sudo is not installed on my machine and I cannot just copy and paste the lines because I have to avoid pasting sudo.

Also fyi ArchWiki also uses the # approach.
- Can't you just select the text without the sudo prefix..?
Neither because it makes it hard to copy paste. If you have to pick one then $ because # is for comments in bash.
- You can just get around this by using some css tricks to display the dollar and pound signs.
- It's not actually part of the command, just some css to add the prefix visually.
  
  That's OK then. If you can double click the text field the the prefix is not highlighted, then I'm happy :)
I would use $ too for the example you’ve posted - it is just assuming a different user.

As long as it is not root, I wouldn’t put it with #.
# is a standard shell prompt for root, and only for root. For commands executed by any other user, including sudo, use $.

In general it is a bad practice to use sudo in documentation because in many distros it is not available by default. I would use su for your example. However system users have no passwords, so you need to become root first, and only after that change user to avoid prompting a password. So I would write

# su -s /bin/bash www-data $ cp /var/www/html/html1 /var/www/html/html2

or

# su -s /bin/sh -c 'cp /var/www/html/html1 /var/www/html/html2' www-data

But if you are sure that sudo is installed and configured on a user's machine, you may write

$ sudo -u www-data cp /var/www/html/html1 /var/www/html/html2
- I disagree completely.
  
  The bad practice is running commands directly as root. It's fine if you prefer for your own environment but sudo is the best practice.
  
  Additionally, which distro doesn't have sudo? I'm sure there are some but by far the majority of distos have and use sudo.
  
  Bad practice is not using sudo (I do use it), but assuming that everyone has sudo installed and configured the same way as you have.
  
  Additionally, which distro doesn’t have sudo? I’m sure there are some but by far the majority of distos have and use sudo.
  
  Almost all distros have sudo. But many of them don't install it by default. Most popular distros except Ubuntu (I mean Debian, Fedora and RHEL clones) provide a choice to user at install time: set the root password or install sudo and enable it for the admin user. In OpenSUSE sudo is installed by default, however it is configured in slightly different way than usually. Etc., etc.
- Agreed that it's bad practice to use sudo.
  Very good idea using su. I never thought of using it like that before.
Edit: looks like this is wrong lol, that's what I get for not verifying. So maybe $ does make more sense!

Original message:

I think I'd go with #.

The non-root user probably doesn't have permission to run the sudo command as www-data user, but root does.

Unless you previously set permissions for the non-root user to sudo as www-data.
- The non-root user probably doesn’t have permission to run the sudo command as www-data user, but root does.
  
  You are wrong. E. g. in Debian (and Ubuntu) the default sudoers file contains
  
  %sudo ALL=(ALL:ALL) ALL
  
  that means that any user in the sudo group is permitted to execute any command as any other user. The same for redhat/fedora, but the group name is wheel there.
  
  lol thanks for the correction
I seem to be in the minority here but I personally prefer using $ and # to denote root. I like this because not everyone uses sudo and might not even have it installed.

That being said, if you already have other commands that are using sudo -u ... to run commands as a different user then it might be best to just be consistent and prefix everything with it, but if there is only a few of those maybe a # cp foo bar && chown www-data bar is an alternative.
- Yeah, being consistent is definitely important. I can avoid sudo in many cases, but there are other pages where half the commands need to be executed as some user.
  My Nextcloud page has that problem where php scripts need to be executed by the right user. But it also contains the installation instructions and there I can avoid using sudo. It's like a 50/50 split between using # and sudo -u on that page :/
Personally i prefer the $ sudo because honestly i don't always notice the symbol at the beginning but sudo is really easy to keep track of whats root and what isn't
- I hadn't thought of it like that. Thanks
You should consider who your audience is, are they all CLI experts familiar with the difference in syntax? That seems unlikely.

I'd always write documentation in a way that's accessible to most users. The difference between $ and # syntax is highly esoteric.

sudo on the other hand is familiar to almost everyone. It's one of the first things mentioned in beginners guides.

I wouldn't even prefix your commands with $ as an experienced user is quite likely to include that when copying the command.

A lot of people are citing the arch wiki as a standard that uses # but isn't the entire meme around arch that its a notably complex system?
- It's ok if you prefix with $ and # IF it's not selectable. It should only be a visual reference for those who know and only helps keep your documentation complete.

28 comments