How to add a group in Linux

How to add a group in Linux

Into this tutorial we will learn how to add group in
Linux using command line mode with different options and commands.

Groups

  •             Users
    are assigned to groups with unique group ID numbers (the GID)
  •             The
    group name and GID are stored in /etc/group
  •             Each
    user is given their own private group
  •             They
    can also be added to their groups to gain additional access
  •             All
    users in a group can share files that belong to the group

Each and every user is a member of at least one
group, called a primary group. In addition, a user can be a member of an
unlimited number of secondary groups. Group membership can be used to control
the files that a user can read and edit. For example, if two users are working
on the same project you might put them in the same group so they can edit a
particular file that other users cannot access.
A users primary group is defined in the /etc/passwd
file and Secondary groups are defined in the /etc/group file.
The primary group is important because files created
by this user will inherit that group affiliation.
Create
a Group with default options:
To  create a group the sysntax is

#
groupadd < name for the group>
#groupadd
linuxelearn
And verify it in /etc/group file with tail
/etc/group
command.
[root@linuxelearn
~]# groupadd linuxelearn
[root@linuxelearn
~]# tail /etc/group
user:x:500:
nagios:x:501:
nagcmd:x:502:apache
rahul:x:503:
ram:x:504:pooja
rpgroup:x:505:rahulp,pooja
ktg:x:506:
admin:x:507:nagios
pooja:x:508:
linuxelearn:x:509:
[root@linuxelearn
~]#
Create
a group with user specified group id (GID)

#
groupadd <option> <name for the group>
#
groupadd –g 595 linuxelearn

Verify it in /etc/group
file
[root@linuxelearn
~]# groupadd -g 510 linuxelearn1
[root@linuxelearn
~]# tail /etc/group
nagios:x:501:
nagcmd:x:502:apache
rahul:x:503:
ram:x:504:pooja
rpgroup:x:505:rahulp,pooja
ktg:x:506:
admin:x:507:nagios
pooja:x:508:
linuxelearn:x:509:
linuxelearn1:x:510:
[root@linuxelearn
~]#
Modifying
the properties of the group

To modify the group properties the syntax is
#groupmod
<option> <arguments> <group name>
The options are
  •             -g to change the group id
  •             -o to override the previous assigned
    id, if it matches with the new one.
  •             -n to change the group name

Change
the GID of the group
  •             #groupmod –g 600 linuxelearn
  •             Verify
    it in /etc/group

[root@linuxelearn
~]# groupmod -g 570 linuxelearn
[root@linuxelearn
~]# tail /etc/group
nagios:x:501:
nagcmd:x:502:apache
rahul:x:503:
ram:x:504:pooja
rpgroup:x:505:rahulp,pooja
ktg:x:506:
admin:x:507:nagios
pooja:x:508:
linuxelearn:x:570:
linuxelearn1:x:510:
[root@linuxelearn
~]#
Changing
the name of the Group
            The
syntax for changing the group name is
            #groupmod –n <new name> <existing
name>
            #groupmod –n linuxelearn rjgroup

[root@linuxelearn
~]# groupmod -n rjgroup linuxelearn
[root@linuxelearn
~]# tail /etc/group
nagios:x:501:
nagcmd:x:502:apache
rahul:x:503:
ram:x:504:pooja
rpgroup:x:505:rahulp,pooja
ktg:x:506:
admin:x:507:nagios
pooja:x:508:
linuxelearn1:x:510:
rjgroup:x:570:
[root@linuxelearn
~]#

In this tutorial we cover all the options of adding
a group in Linux. 

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