Skip to content

Latest commit

 

History

History
113 lines (79 loc) · 6.55 KB

AddingAndRemovingUsers.md

File metadata and controls

113 lines (79 loc) · 6.55 KB

Adding and Removing Users

You may go for years (as I have) without needing to add (or remove) a user from your Raspberry Pi. But chances are good that at some point, you will need to do this - if only to have an unprivileged user for testing.

WARNING: There is far too much incorrect guidance that may place highly in your search results. In the best case, this poor guidance will waste your time. At worst, it creates a mess that may get out of hand if not dealt with quickly. Here's the correct way to add a user for RPi OS, but note that this may vary with other distributions:

adduser, or useradd... What's the difference?

  1. Know the difference between adduser and useradd!

  2. Because RPi OS is a derivative of Debian, know that for **routine use **, **adduser ** is a one-stop command solution. It adds the user, prompts you to create a password, and creates a ready-to-use /home directory for the new user. Forget about useradd unless you need something non-routine; e.g. no /home directory, no login password, etc. Here's a preview in which we add a user named stooge:

    $ sudo adduser stooge
Adding user `stooge' ...
Adding new group `stooge' (1001) ...
Adding new user `stooge' (1001) with group `stooge' ...
Creating home directory `/home/stooge' ...
Copying files from `/etc/skel' ...
New password:********         # <-- ENTER PASSWORD
Retype new password:********  # <-- ENTER PASSWORD (CONFIRM)
passwd: password updated successfully
Changing the user information for stooge
Enter the new value, or press ENTER for the default   # <-- ALL VALUES BELOW ARE OPTIONAL
	Full Name []: Moe
	Room Number []:
	Work Phone []:
	Home Phone []:
	Other []:
Is the information correct? [Y/n] Y

  3. At this point, user stooge has been created, along with a matching group - also called stooge. User stooge can log in, has a home directory and other items a user needs to begin using the system. He can also login via SSH.

deluser, or userdel... What's the difference?

As before, owing to its Debian heritage, deluser is the go-to command for routine use in removing a user account. Note that there may be much more work needed to remove a user account than there was creating it - but that depends on the circumstances. If you want a walk-through of the more comprehensive task of removing a user from your system, see the References below. For this recipe, only the actual user account deletion with deluser is covered, but if you take the time to review man deluser you'll see its options cover many tasks associated with account deletion.

We'll use the hapless user stooge as an example again. Since user stooge wasn't a particularly productive user, it was decided not to backup or save any of his files:

$ sudo deluser --remove-all-files stooge 
Looking for files to backup/remove ...
/usr/sbin/deluser: Cannot handle special file /dev/media1
... a long list of files `deluser` can't handle (see Ref. 3 below), and finally:
Removing files ...
Removing user `stooge' ...
Warning: group `stooge' has no more members.
Done.

All of the noise in the output - the Cannot handle... warnings are apparently due to a harmless but annoying bug in deluser.

group membership can be expanded

  1. By default, a "regular" user belongs only to the default group created when the user was added to the system. This may be checked as follows:

    stooge@raspberrypi4b:~$ groups
stooge

    Or, as another user (user pi for example):

    pi@raspberrypi4b:~$ groups stooge
stooge : stooge
pi@raspberrypi4b:~$

  2. A list of all groups in the system is in /etc/group. It may be useful to add the new user to additional groups (e.g. group users). This must be done in a particular way to add group memberships, otherwise you may inadvertently replace one group membership for another. This task will need to be done by a privileged user (pi in this case):

    pi@raspberrypi3b:~ $ sudo usermod -a -G <groupname> <username>

# to add user `stooge` to group `users`:

pi@raspberrypi3b:~ $ sudo usermod -a -G users stooge

    See man usermod for details

    Another way to accomplish this (in Debian at least) is with the adduser command:

    pi@raspberrypi3b:~ $ sudo adduser stooge users
Adding user `stooge' to group `users' ...
Adding user stooge to group users
Done.

    Know this:

    Group membership additions are not instantaneous. Group membership of a user only takes effect on the next login.

strange things re group sudo

Sometimes it seems there are other factors at work. This Q&A is an example of that; the OP seemed to have removed his user from group sudo properly, yet his user continued to have access to sudo?! There are some unanswered questions, but as my hero said once, "new shit has come to light". Specifically in the form of using commands vigr & vigr -s to edit the /etc/group and /etc/gshadow files, andgpasswd and other possibilities covered in this U&L SE Q&A.

References:

  1. The Debian Wiki: SystemGroups
  2. How to Delete a User on Linux (and Remove Every Trace) - a How-To-Geek article
  3. Q&A: Strange output when deleting user - indicates a harmless but annoying bug is responsible
  4. How do I remove a user from a group? - some alternatives
  5. Remove sudo privileges from a user (without deleting the user) - seems the accepted answer is wrong??
  6. Sudo user not in sudo group? - is this related to the mystery?
  7. Sudo still works despite removing my user from group - THE mystery!