Linux users and groups CRUD

Creating, deleting and updating users and groups is something I always struggle with remembering. After all I am not a sysadmin so I don't do it too often I guess. So I'm putting together a cheat sheet/article of my own.

Create normal user

When I say normal user I mean as opposed to system user, which I will write some commands for as well.
Typically for a normal user we would also set home folder and a default bash.

For adding users there are two of confusingly similar commands that are used. useradd being the "low level" command and adduser being the "high level" command, which is suppose to mean more user friendly. And well, of course, some distros have GUI as well 😃

useradd

man page
here you need specify:

• create home folder -m
• assign to a main group -g
• bash as default shell for user -s - or else it might be /bin/sh

and then set password in second command

useradd -m -g users -s /bin/bash testuser
passwd testuser

adduser

man page
this command will prompt you for password and fullname and some other stuff
it will create a group with same name as user and assign the OS default shell

adduser testuser

Delete user

There is also a low level userdel and high level command deluser for deleting. But really the low level version is enough to know about, it's more than simple enough.

userdel

man page specify -r to remove users home directory and mail spool

userdel -r testuser

List users

less /etc/passwd

Create group

groupadd newgroup

Add user to group

usermod -a -G newgroup testuser

List groups

cat /etc/group

Create service user

useradd -r serviceuser

show user ids

id testuser