UNIX User Management

This is one of the blog posts to set something in my mind that I’m always looking up. Linux has lovely tools for adding and managing users, but I can never remember them. I’m old skool and BSD-centric, so I tend to just use vipw, but it’s better to use the tools. So, with no further ado:

Creating a User

Linux

sudo adduser <username>

FreeBSD

sudo adduser

Creating a Group

Linux

sudo groupadd <group>

FreeBSD

sudo pw groupadd <group>

Adding a User to a Group

Linux

sudo usermod -a -G <group> <user>

FreeBSD

sudo pw groupmod <group> -m <user>

Adding a User to Multiple Groups

Linux

sudo usermod -a -G <group1>,<group2>,<group3> <user>

Changing the User’s Primary Group

Linux

sudo usermod -g <group> <user>

FreeBSD

sudo pw usermod -n <user> -g <group>

Deleting a User

Linux

sudo userdel -r <user>

FreeBSD

sudo rmuser <user>

Deleting a Group

Linux

sudo groupdel <group>

FreeBSD

sudo pw groupdel <group>

Details

adduser

With adduser on Linux you just supply a username, you’ll get prompted for everything else, including the username on BSD systems. Confusingly, Linux also has useradd. Unless you’re writting scripts, you probably never want this. It’s not interactive. While running sudo useradd <username> will add the account to the password file, it won’t setup the home directory or copy in init files unless you explicitly tell it to.

usermod for groups

The -a is for add or append. If it’s left off the listed groups will replace the existing ones. This only works with -G.

groupmod

The BSD only pw groupmod simple adds the user to the group. FreeBSD doesn’t have a simple way to add a user to multiple groups in one command. However, the -m option can take multiple, comma separated list of users.

userdel

The -r removes the user’s home directory, without it, the user is removed from the password file, but the it’s files are left intact.

rmuser

rmuser does a lot of additional clean up, like killing running process, deleting email, and removing cron jobs.

groupdel

The Linux groupdel won’t remove a group if it’s the primary group of any user. You must change the user’s group or delete the user first. FreeBSD doesn’t seem to have this feature.

Now maybe I’ll remember next time I need to do user management.