user and group administration in linux with examples step by step.

User's & Group's Administration

http://linuxserverworldadmin.blogspot.in/2015/03/user-administration-in-linux.html

Scenario
There are two groups :

1)salesgrp : salesgrp ID=2000

Sales users should exist in salesgrp

2)fingrp : fingrp ID=3000

Finance users should exist in fingrp 
tom
joy

Now create the users with following parameters:
ali u - 2001
tom c - "Mang of Sales Dept" ram d - /sa lesdept
shyam s - /bi n/ksh
joy g - salesgrp/2000

Create user abdul with following parameters
u - 2002
c - "Di rector of Sales Dept"
d - / salesdept
s - / bin/csh
g - salesgrp/2000
G - f ingrp,mrkgrp


Create a user ali whose user id is 2001
[root@server~]# useradd -u 2001 ali 
[root@server~]# grep ali /etc/passwd
Create a user tom whose comment is "Mang of Sales Dept"
[root@server~]# useradd -c "Mang of Sales Dept" tom [root@server~]# grep tom /etc/passwd
Create a user ram whose home directory exist in /salesdept folder
[root@server~]# mkdir /salesdept
[root@server~]# useradd -d /salesdept/ram ram [root@server~]# grep ram /etc/passwd

Create a user shyam whose shell is ksh
[root@server~]# cat /etc/shells
[root@server~]# useradd -s /bin/ksh shyam 
[root@server~]# grep shyam /etc/passwd
Create a user joy/jack whose primary group id is 2000/salesgrp
[root@server~]# groupadd -g 2000 salesgrp
[root@server~]# grep salesgrp /etc/group

[root@server~]# useradd -g 2000 joy 
or
[root@server~]# useradd -g salesgrp jack

[root@server~]# grep 2000 /etc/passwd
Create a user abdul with all parameters as in scenario
[root@server~]# useradd -u 2000 -g salesgrp -c "Director of Sales Dept"
-d /salesdept/abdul -s /bin/csh abdul
[root@server~]# grep abdul /etc/passwd
abdul:x:2000:2000:Director of Sales Dept:/salesdept/abdul:/bin/csh
To Modify the parameter of existing user abdul
[root@server ~]# usermod -u 3000 -g fingrp -c "Mang of fin Dept" -d /findept/abdul -m -s /bin/ksh abdul
[root@server ~]# grep abdul /etc/passwd
abdul:x:3000:3000:Mang of fin Dept:/findept/abdul:/bin/ksh
[root@server ~]# useradd scott

[root@server ~]# grep scott /etc/passwd 
scott:x:3001:3001::/home/scott:/bin/bash

To change login name

[root@server ~]# usermod -l tiger scott

[root@server ~]# grep tiger /etc/passwd 
tiger:x:3001:3001::/home/scott:/bin/bash

To lock the Account
[root@server ~]# passwd tom
[root@server ~]# usermod -L tom
login & check


To Unlock the Account
[root@server ~]# usermod -U tom
login & check
To delete only users account but not home directory & mail account.
[root@server ~]# userdel tom
[root@server ~]# ls /home
To delete users account along with home directory & mail account.
[root@server ~]# userdel -r tom
[root@server ~]# ls /home
Adding groups
Adding a new group
[root@server ~]# groupadd amerpetgrp
[root@server ~]# grep amerpet /etc/group amerpetgrp:x:3002:
adding a new group with gid 5000
[root@server ~]# groupadd -g 5000 banjaragrp

[root@server ~]# grep banjaragrp /etc/group
banjaragrp:x:5000:
modifying group with gid
[root@server ~]# groupmod -g 6000 banjaragrp
[root@server ~]# grep banjaragrp /etc/group
banjaragrp:x:6000:
Changing the name of a existing group
[root@server ~]# groupmod -n banjarahills banjaragrp
[root@server ~]# grep banjarahills /etc/group
banjarahills:x:6000:
[root@server ~]# groupmod -g 6000 banjaragrp
[root@server ~]# grep banjaragrp /etc/group
banjaragrp:x:6000:


To delete group account

[root@server ~]# groupdel banjaragrp
[root@server ~]# grep banjarahills /etc/group
Adding Multi users into group salesgrp
[root@server ~]# useradd jack
[root@server ~]# useradd shyam 
[root@server ~]# useradd wiliam
[root@server ~]# gpasswd -M jack,shyam,wiliam salesgrp
To Check the Status:
[root@server ~]# grep salesgrp /etc/group salesgrp:x:2000:jack,shyam,wiliam
Removing user wiliam from group salesgrp
[root@server ~]# gpasswd -d wiliam salesgrp
To Check the Status:
[root@server ~]# grep salesgrp /etc/group salesgrp:x:2000:jack,shyam
Adding New user wiliam to group salesgrp
[root@server ~]# gpasswd -a wiliam salesgrp
To Check the Status
root@server ~]# grep salesgrp /etc/group
salesgrp:x:2000:jack,shyam,wiliam
[root@server ~]# chage -l jack
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^OUTPUT^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Last password change : Jul 14, 2008
Password expires : never
Password inactive : never
Account expires : never
Minimum number of days between password change : 0
Maximum number of days between password change : 99999
Number of days of warning before password expires : 7
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[root@server ~]# system-config-users &