Can you tell me what the difference is between
All I know so far is that cat is used for displaying contents of file and concatenation.
Ask Ubuntu is a question and answer site for Ubuntu users and developers. It only takes a minute to sign up.Sign up to join this community
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
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.
Cat is a standard unix utiliy and a most frequently used command which concatenate files and print on the standard output.
You may open a terminal (press CTRL+ATL+T) & type
man cat to know more about the command and its usage.
Further, the difference between
cat & using
-rw------- 2 root root 4096 996 Feb 6 20:39 log.txt
Above seen is a file which only a root user (or a user who's within root group) can read/write. In such situation you will need to use
sudo cat filename to print the output.
Assume it helped you to understand more.!