Basic Ubuntu Commands

1. Enable Root in Ubuntu

To enable root directory execute the following command in terminal.

sudo passwd root

2. Add New User

To add a new user account execute the following command in terminal.

sudo adduser username

3. Delete User Account

To delete the user account execute the following command in terminal.

sudo deluser username

4. Lock/Unlock the User Account

To lock the user account execute the following command in terminal.

sudo passwd -l username

To Unlock the user account execute the following command in terminal.

sudo passwd -u username

5. Change Permission for File

chmod is a Unix command that lets you tell the system how much (or little) access it should permit to a file. To change the permission you must login in root using su on terminal.

chmod 700 /directory/filename

6. Change Permission for Connection Editor

You can set permission to connection editor using chmod command. To change the permission you must login in root using su on terminal.

chmod 700 /usr/bin/nm-connection-editor

You can remove permission for connection editor by executing the following command in terminal.

chmod 777 /usr/bin/nm-connection-editor

7. Change Permission for Media

You can set permission to media using chmod command. To change the permission you must login in root using su on terminal. After executing the command all the USB connections are get locked.

chmod 700 /media/

You can remove permission for media by executing the following command in terminal.

chmod 777 /media/

8. Change Permission for Appearance

You can set permission to appearance using chmod command. To change the permission you must login in root using su on terminal. After executing the following command desktop background cannot be changed in normal user.

chmod 700 /usr/bin/gnome-appearance-properties/

9. Change Permission for Screensaver 
You can set permission to screensaver  using chmod command. To change the permission you must login in root using su on terminal. After executing the following command screensaver cannot be changed in normal user.

chmod 700 /usr/bin/gnome-screensaver-preferences/

10. Change Permission for Keyboard

You can set permission to keyboard preference  using chmod command. To change the permission you must login in root using su on terminal. After executing the following command keyboard preference cannot be changed in normal user.

chmod 700 /usr/bin/gnome-keyboard-properties