Can you tell me what the difference is between cat and sudo cat?
All I know so far is that cat is used for displaying contents of file and concatenation.
For a little humour I would say that cat is an animal and sudo cat is a feline with superpowers. :D
sudo is a command that you use to obtain root privileges. root is a special user that manages the machine, and for this he/she has superpowers. For example, if there is a file that only root can see its contents, and you are logged in as a normal user, you can use
$ sudo cat name_of_the_file
to read it. Also if there is a program that only root can run, like the reboot command:
$ reboot
warning: must be root!
$ sudo reboot
rebooting...........
THE CATCH IS: you must be specially (and manually) assigned by root to have permission to use sudo. The permission is given in a file called /etc/sudoers. In Ubuntu, the first user, the one created during install, is automatically a sudoer. But the subsequent users are not. You have to add them manually to the group sudo whose members are allowed to use the command sudo.
By the way, /etc/sudoers is a file that only root can see. So if you do
$ cat /etc/sudoers
you will not be able to see its contents. But if you do:
$ sudo cat /etc/sudoers
you are good.
Hope this helps.
