Links

• http://freshtutorial.com/add-users-groups-change-password-linux-terminal/
• http://webtools.live2support.com/linux/passwd.php

Maintain #

Do not edit passwd and groups directly

groups markus				# show groups of a user
id markus				# show groups of user with ids
sudo usermod -g markus markus		# change primary group of an user
sudo usermod -aG groupname markus 	# add user to a group
sudo usermod -rG groupname markus 	# remove user from a group
sudo gpasswd -d markus groupname	# remove group of a auser

/etc/passwd#

• contains all Users
• Benutzer:Passwort:User-ID:Group-ID:Kommentar:home-Verzeichnis:Shell
• there is a shadow file under /etc/shadow

/etc/group#

• contains all groups

Editing the files above is not suggested, use following commands to maintain users and groups

who
who -a
users
w
cat /etc/passwd
cat /etc/group
usermod -G deploy,root root
usermod -a -G groupname username
usermod -d /path/to/new/homedir/ username
useradd
chown -R <user> *|change owner for whole subfolder
chmod <rights> <file>|x=1 w=2 r=4, oga = owner group all
chgrp
adduser username
passwd username
addgroup groupname
userdel username
deluser user group
groupdel groupname
vipw -s : Edit /etc/passwd file
vigr -s : Edit /etc/group file

chage

change user password expiry information

chage -l username
chage -E 03/31/2014 -m 5 -M 90 -I 30 -W 14 username

Lock/Unlock user

passwd -l <username>	Lock user
passwd -u <username>	Unlock user
passwd -a -S	Show list

List columns:

1	login name
2	locked password (L) / has no password (NP) usable password (P).
3	date of the last password change
4-7	password: minimum age, maximum age, warning period, inactivity period in days