Use
groupadd command in linux is used to create a new group with values specified on command line plus the default values mentioned in the system.
Synopsis
groupadd [Options] group
Example
The list of existing groups in the system is available in /etc/group file. We create a new group named Centos and check the entry in this file.
![After groupadd command in linux](https://dextutor.com/wp-content/uploads/2019/09/groupadd-1.jpg)
The Centos group is created with a default GID 1009.
Options available with groupadd command in linux
1. To assign GID of choice
-g : options assigns a GID of user’s choice to the newly created group. The mentioned GID must be free to use i.e., no exiting group should have that GID.
For Example: We create a new group Ubuntu having GID 2025.
![](https://dextutor.com/wp-content/uploads/2019/09/g-2.jpg)
2. Overriding /etc/login.defs default values
-K : option overrides the default values (such as GID_MIN, GID_MAX) specified in the /etc/login.defs file.
3. Create a system group
-r : option creates a group with GID from SYS_GID_MIN-SYS_GID_MAX (check the values in /etc/login.defs file)
![After -r option with groupadd](https://dextutor.com/wp-content/uploads/2019/09/r-1.jpg)
4. Create groups with same GID
-o : option allows you to create a group with non-unique GID i.e., there will be multiple groups with the same GID.
![Before -o option with groupadd](https://dextutor.com/wp-content/uploads/2019/09/before-o.jpg)
The group Ubuntu has the GID 2025. Now, we will create another group Redhat with the same GID.
![Using -o option with groupadd command in linux](https://dextutor.com/wp-content/uploads/2019/09/o-1.jpg)
The contents of /etc/group shows that now two groups Ubuntu and Redhat have the same GID.
![After -o option with groupadd command in linux](https://dextutor.com/wp-content/uploads/2019/09/after-o.jpg)
PPT on groupadd command
Video on groupadd command
Other useful commands in Linux
Some helpful questions
Q1. Write the command to create a group named Cars whose GID is 3030.
Q2. Which file contains the information related to the existing groups in the system?
Q3. What is the difference between a normal group and a system group?