User Management

Adding User

useradd testuser

Adding user with home folder

useradd -d /home/testuser testuser

Adding user without home folder

useradd -M testuser

Changing user password

passwd testuser

Adding user with specific user id

useradd -u 550 testuser

Adding user with specific group

useradd -g 550 testuser

Adding user with specific secondary groups

useradd -G admins,dba,tools testuser

Checking user details

id testuser

Adding user with expiry date

useradd -e 2016-03-25 testuser

Checking age to user account

chage -l testuser

Adding user with full name or comment

useradd -c "Test User" testuser

Adding user with specific shell

useradd -s /bin/bash testuser

Adding user with no login

useradd -s /sbin/nologin testuser

User's default skeleton directory

/etc/skell

Adding user without adding user to any group

useradd -N testuser

Adding user as a system user

useradd -s testuser

Adding user with custom skeleton directory

useradd -k /etc/custom-skell testuser

Files affected on adding a user

/etc/passwd

/etc/group

/etc/shadow

/etc/gshadow

Config files while adding user

/etc/login.defs

/etc/default/useradd

Changing user login name

usermod -l testuser-new testuser

Lock user account

usermod -L testuser

Unlock user account

usermod -U testuser

Creating un-encrypted password for user

usermod -p password testuser

Adding user to other secondary groups

usermod -aG dba testuser

Deleting a user

userdel testuser

Deleting a user with home folder

userdel -r testuser

Checking a user from /etc/password file

grep -E --color testuser /etc/passwd