2.4 KiB
#Basic Information
Let's get some entries with 'getent', e.g. passwd or group.
getent passwd
getent group
Obviously:
getent shadow
will require sudo.
Examples
sudo adduser maestro
add user 'maestro'
This depends upon the settings in the /etc/default/useradd file and /etc/login.defs
sudo useradd -m pinkie
add user 'pinkie' with a home directory
sudo adduser -m -e 2017-04-25 temp
add expiry date to user
userdel maestro
delete maestro
userdel -r maestro
delete maestro and hir homefolder
groups
find which group you are in
id
same
id -Gn maestro
Find which groups maestro is in
deluser --remove-home maestro
delete user maestro
usermod -aG sudo maestro
add user maestro to group sudo
cat /etc/passwd
list users' passwords (and therefore users)
groupadd awesome
create the group 'awesome'
passwords are stored in /etc/shadow.
there are user accounts for processes such as 'bin' and 'nobody' which are locked, so they're unusable.
passwd -l bin
lock the user 'bin'
more /etc/passwd | grep games
we find the name, password and user id of the user 'games'. I.e. the password is 'x', and the user id is '5'. The password is an impossible hash, so no input password could match.
groupdel learners | delete the group 'learners'
gpasswd -d pi games | remove user 'pi' from the group 'games'
id games
find the id number of group 'games' (60)
usermod -aG sudo maestro
add user to group 'maestro'
user info is stored in /etc's passwd, shadow, group and gshadow
Defaults
The default new user profiles are under /etc/skel.
Shells
A list of shells is in /etc/shells.
Only root can run shells not listed in /etc/shells
To change a user's shell:
usermod --shell /bin/bash user1
Alternatively, change the shell in /etc/passwd.
Usermod also lets you change a user's username:
usermod -l henry mark
However, this will not change the home directory.
Lock a user out of an account:
usermod -L henry
More Arguments
-G or -groups adds the user to other groups:
usermod -G sudo henry
-s adds the user to a shell.
-u let's you manually specifiy a UID.
Groups
In /etc/group, a group file may look like this:
sudo:x:27:mike,steve
We can use groupmod, like like usermod, e.g. to change a name:
groupmod -n frontoffice backoffice
Delte a group:
groupdel frontoffice