This post provides some Linux commands that can be utilized for user and group related assignments. with this commands, you can add,remove,delete users and groups. To run certain commands you should have root or sudo level rights on Linux machine.
Following are the commands in depth:
Id commands provides the number of active users and their IDs. Using this command can get the users login and group information.
# id uid=0(root) gid=0(root) groups=0(root)
last command is used to get the last login user detail on the system.
# last reboot system boot 2.6.32-042stab08 Sun Jul 5 13:54 - 12:54 (801+23:00) reboot system boot 2.6.32-042stab08 Fri Mar 7 03:21 - 13:53 (485+09:31) reboot system boot 2.6.32-042stab05 Mon Sep 17 22:37 - 13:53 (1020+15:15) reboot system boot 2.6.32-042stab05 Mon Sep 17 20:07 - 22:36 (02:28) reboot system boot 2.6.32-042stab05 Tue Apr 24 20:06 - 20:07 (146+00:00) reboot system boot 2.6.32-042stab05 Thu Apr 12 22:14 - 20:07 (157+21:52) reboot system boot 2.6.18-194.8.1.e Mon Apr 2 10:06 - 22:13 (10+12:06) reboot system boot 2.6.32-042stab03 Tue Feb 21 10:41 - 03:30 (40+15:49) wizap pts/1 c-68-51-136-80.h Sun Nov 20 11:16 - 12:00 (00:43) reboot system boot 2.6.32-042stab03 Mon Nov 7 06:52 - 03:30 (146+19:38)
Who command display the current logged in user on the system.
# who prashant tty8 2017-10-03 12:20 (:0) prashant pts/10 2017-11-02 13:40 (:0)
Whois command provides the name of the user by which you are currently logged on the system.
# whoami root
This command used to create a group on the system. Before running this command make sure a are logged in as a root otherwise you get “permission denied” error.
# groupadd dba
Useradd command used to create a user on the system. Type the below command create a new user and add that user to the dba group.
# useradd -c "Rahul Sharma " -g admin -m rahul
You can check a group of “rahul” user with id command like below:
# id rahul uid=81(rahul) gid=81(dba) groups=81(dba)
This command used modify or change the setting of existing user account. Only root user can modify the existing user account. Using usermod –help you can get more options.
# usermod -a -G Groupname Username
This command used to modify or change the setting of existing group. Only root user can modify the existing group. This command works similarly to usremoad command.
# groupmod -A Username Groupname
This command is used to delete the user from the system.
# userdel rahul
This command works same as useradd command but it is more interactive command. It is also user friendly and interactive. This command is also prompt to set a password for the user.
# adduser neo Adding user `neo' ... Adding new group `neo' (1007) ... Adding new user `neo' (1006) with group `neo' ... Creating home directory `/home/neo' ... Copying files from `/etc/skel' ... Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully Changing the user information for joe Enter the new value, or press ENTER for the default Full Name : Room Number : Work Phone : Home Phone : Other : Is the information correct? [Y/n] y
This command used to delete the user from the system.
# rmuser neo
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