Bootstrap FreeKB - Linux Commands - sudo
Linux Commands - sudo

Updated:   |  Linux Commands articles

This assumes you are familiar with the /etc/sudoers file

In this example, john.doe attempts to issue the reboot command without sudo, and gets Permission denied. This is expected, as the reboot command requires elevated privileges.

[john.doe@server1 ~]# reboot
reboot: Permission denied

 

On a systemd system, the systemctl command is used to reboot the system, and only root has permission to execute the systemctl command.

[john.doe@server1 ~]# ls -l /bin/systemctl
-rwxr-xr-x. 1 root root 717568 Feb  4 10:30 /bin/systemctl

 

sudo is used to issue a command with elevated privileges. Let's say john.doe uses sudo to invoke the reboot command.

[john.doe@server1 ~]# sudo reboot

 

If john.doe has not been added to the /etc/sudoers file, the following will be displayed.

john.doe is not in the sudoers file. This incident will be reported.

 

If john.doe has been added to the /etc/sudoers file, but has not been granted permission to the command being issued, the following will be displayed.

john.doe is not allowed to run sudo on server1.  This incident will be reported.

 

John Doe can be granted permission to the reboot command (or any other command).

 

If John Doe is granted sudo permission with password, John will be prompted to provide his password, like this.

[john.doe@server1 ~]# sudo reboot
Password for john.doe: ******

 

If John Doe is granted sudo permission with the NOPASSWD option, John will not be prompted to provide his password and the system will reboot.

[john.doe@server1 ~]# sudo reboot

 




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