The “root” super user is the king of users in Linux/Unix. Having root access grants full and unlimited access to the Linux box. I will show you how to allow root access to a user in a Linux system. Typically, root level access is used in system administration. So it is always a pain to give root access to other users. You need to be careful and should withdraw the access once the need to do so is over.
According to Linux file system permissions, root or super user has full permission to read(r), write (w) and execute(x) any file. By default root user id is '0'.
I am going to create two users namely user1 and user2. Then I will show you how to give root access to user1 .
Method 1: Adding to Root Group using usermod
Let see how we can grant normal user root access by adding to root group.
[[email protected] Desktop]# adduser user1
[[email protected] Desktop]# adduser user2
[[email protected] Desktop]# groupadd test
These are the groups I have in my Linux box.
[[email protected] /]# groups
root bin daemon sys adm disk wheel
I am going to add user1 to root group as follows:
[[email protected] Desktop]# usermod -G root user1
The command given below provides the existing user with the root privilege
[[email protected] Desktop]# usermod -g 0 -o root_user
Method 2: Adding to Root Group using Useradd Command
I have added a new user, 'user3' to the root group using one single command:
[[email protected] /]# useradd -m -G root user3
[[email protected] /]# groups user3
user3 : user3 root
Another option using useradd command
Useradd -c “Imitation Root” -d /home/root_user -m -k /etc/skel -s /bin/bash -u 0 -o -g root root_user
Method 3: Editing /etc/passwd file
Edit /etc/passwd for the particular user. Change the user's UID and GID to '0'. This will give root permissions to user.
Now, temproot user should have root privilege:
Note: This is not the recommended method for granting root access
Method 4: Setting as Sudo User
The sudo configuration file is /etc/sudoers and you can edit this file using visudo command: # visudo.
Using visudo protects from conflicts and guarantees that the right syntax is used.
To give full access to specific users
Add the entry given below in the file:
bob, tom ALL=(ALL) ALL
Following this method is not a good idea because this allows both bob and tom to use the su command to grant themselves permanent root privileges. Thereby skipping the command logging features of sudo.
Granting access to specific files to one particular user
This entry allows bob and all the other members of the group operator to gain access to all the program files in the /sbin and /usr/sbin directories, as well as the privilege of running the command /usr/oracle/backup.pl.
bob, %operator ALL= /sbin/, /usr/sbin, /usr/oracle/backup.pl
If you have any questions or thoughts to share on this topic, use the feedback form.