OpenPeta » User and Group Management

How to change user name in Linux

admin — Mon, 10 Mar 2008 05:27:00 +0000

Sometime you may want to change the user login name into different one,
In that case you can use two options

(Login or switch to root mode – su)

Method 1: ( Using usermod command )
usermod -l newname oldname

Example
#usermod -l anthoniraj antony

Here the user antony has been changed to anthoniraj

Method 2 : ( Using chfn command )
chfn -f newname oldname

Example
#chfn -f thiraviam thiravi

Here the user thiravi has been changed to thiraviam

Note : The old user name should exists in /etc/passwd file .
These above two commands will only change the user name, not user home directory.

Group Management

admin — Thu, 18 Oct 2007 08:40:00 +0000

1) The “groupadd” command creates a new group account
[root@MB327SCS068 ~]# groupadd netadmin
groupadd: group netadmin exists
[root@MB327SCS068 ~]# groupadd network

2) Adding users into network group
[root@MB327SCS068 ~]# useradd antony -g network
useradd: user antony exists
[root@MB327SCS068 ~]# useradd antonyraj -g network
[root@MB327SCS068 ~]# useradd ligory -g network
[root@MB327SCS068 ~]# useradd basha -g network

3) Setting and changing group password (gpasswd)
[root@MB327SCS068 ~]# gpasswd network
Changing the password for group network
New Password:
Re-enter new password:

4) Using “groupmod” command , we can change the group id (option -g) and name (-n)
[root@MB327SCS068 ~]# groupmod -n admin network

4) Deleting Group “groupdel” – You may not remove the primary group of any existing user. You must remove the user before you remove the group.
[root@MB327SCS068 ~]# groupdel admin
groupdel: cannot remove user’s primary group.
[root@MB327SCS068 ~]# userdel antonyraj
[root@MB327SCS068 ~]# userdel
usage: userdel [-r] name
[root@MB327SCS068 ~]# userdel ligory
[root@MB327SCS068 ~]# userdel basha
[root@MB327SCS068 ~]# groupdel admin

Commands for Managing Users

admin — Thu, 20 Sep 2007 03:58:00 +0000

The following commands are used to manage the users on your Linux OS
1. useradd – Create a new user or update default new user information
Example :
[root@myserver ~]# useradd admin

2. passwd – Used to change the user passwd
Example :
[root@myserver ~]# passwd admin
Changing password for user admin.
New UNIX password:
Retype new UNIX password:
passwd: all authentication tokens updated successfully.
(For full details – Refer User Creation Article)

3. userpasswd – A graphical tool to allow users to change their passwords.
Example :
[root@myserver ~]# userpasswd (display one GUI window for changing password)

4. userdel – Delete a user account and related files
Example :
[root@myserver ~]# userdel -r admin
[root@myserver ~]#
The -r option
All user details will be removed from /etc/passwd , /etc/group and /etc/shadow .

5. userinfo – A graphical equivilient to chfn.
Example :
[root@myserver ~]# userinfo

6. usermod – Modify a user account
Example :
i) Changing User home directory
usermod -d /usr/antony
ii) Changing user shell
usermod -s /bin/csh
iii) Setting user expiry date (Date format : YYYY/MM/DD)
usermod -e 2007/09/30

7. usernetctl – allow a user to manipulate a network interface if permitted
Example :
[root@myserver ~]# usernetctl
usage: usernetctl
[root@myserver ~]# usernetctl eth0 report
[root@myserver ~]# usernetctl eth0 up
[root@myserver ~]#

8. users – print the user names of users currently logged in to the current host
Example :
[root@myserver ~]# users
root raj exam1
[root@myserver ~]#

Changing User Information

admin — Tue, 11 Sep 2007 07:24:00 +0000

Using ‘chfn’ command (In Redhat EL4) , we can enter the user information, the same thing you can do with GUI mode using ‘userinfo -a ‘ command

[root@MB327SCS068 ~]# chfn root
Changing finger information for root.
Name [root]: root
Office [vit]: vit
Office Phone []: 1234567
Home Phone []: 1234567

Finger information changed.

Using finger command you can view the user information

[root@MB327SCS068 ~]# finger root
Login: root Name: root
Directory: /root Shell: /bin/bash
Office: vit, 123-4567 Home Phone: 123-4567
On since Tue Sep 11 10:27 (IST) on :0 (messages off)
On since Tue Sep 11 12:22 (IST) on pts/1 from 192.168.0.106
New mail received Mon Sep 10 14:13 2007 (IST)
Unread since Thu Sep 6 11:20 2007 (IST)
No Plan.

Locking and Unlocking User Password

admin — Sat, 25 Aug 2007 05:23:00 +0000

Some times the administrator can lock or unlock the user password
means , the user cannot change the password if administrator set the lock option.
the syntax is

passwd -l / -u username

l – lock the password (user cannot change their password)
u – unlock the password (user can change their password)

Eg :

[root@MB327SCS068 ~]# passwd -l antony
Locking password for user antony.
passwd: Success

[root@MB327SCS068 ~]# passwd -u antony
Unlocking password for user antony.
passwd: Success.

Finding All Users and Groups In Linux Machine

admin — Sat, 25 Aug 2007 05:02:00 +0000

We have lot of commands for user management like useradd ,passwd but there is no separate command for finding all users in our Linux machine , But one powerful
command is ‘cut’ with some options we can find all users on our system

1) Displaying All users (need root mode)

cut -d : -f 1 /etc/passwd

2) Displaying all groups

cut -d : -f 1 /etc/groups