User Information

# useradd user_name [to add a new user]

# passwd user_name [to set user password]

# userdel user_name [to delete a user]

# passwd -d user_name [to delete user password]

# groupadd group_name [to add a new group]

# groupdel group_name [to delete a group]

*When an user is created , it makes five new changes-

1. /etc/password [contains user id, group id etc]

2. /etc/group [contains group information]

3. /etc/shadow [password encryption]

4. /home/user_directory [new directory is created]

5. /var/spool/mail/user_directory [user mail box is created]

# cat /etc passwd or group or shadow [to show password/shodow/group]

*Arif : X : 532 : 535 : : /home/arif/bin/bash

UserName UserID User Group ID

# usermod -c “ “ user_name [to write comment between password]

Arif : X : 532 : 535 : : /home/arif/bin/bash

# id -u user_name [to show user ID]

# usermod -u 700 user_name [to change user ID as 700]

# id -g user_name [to show user group ID as 800]

# groupmod -g 800 user_name [to change group ID]

# passwd -l user_name [to lock a user]

# passwd -u user_name [to unlock a user]