Allow a normal user to run commands as root in Unix/linux

Use sudo command which is use to execute a command as another user.

The sudo command allows users to do tasks on a Linux system as another user.

Sudo is more  secure then su command.

Log files : /var/log/secure (Red Hat/Fedora / CentOS Linux)  

   /var/log/auth.log (Ubuntu / Debian Linux).

So we can get the details using above log files that which user has perform which task or command using sudo or as privilage user.

Below is the general syntax for /etc/sudoers file

 

USER HOSTNAME=COMMAND

Use of Sudo : 

1) #visudo

2 )Enter this line in open file  sanjay localhost=/sbin/reboot

3 ) Save the file

4 ) Now user sanjay can reboot the server using below command

# sudo /sbin/reboot

You can see the information of this user in /var/log/auth.log  or /var/log/secure file

 

Examples : 

1) Specify multiple commands for user Sanjay:

Sanjay ALL=/sbin/reboot, /etc/init.d/apache2 , /etc/init.d/mysql

2) Allow user Sanjay to run /sbin/reboot without any password 
Sanjay ALL= NOPASSWD: /sbin/reboot

3) Allow user sanjay to run any command from /usr/bin directory on the localhost:
sanjay localhost = /usr/bin/*