11

Asking because of curiosity. :)

When I type 

sudo su

It asks for my user password. And when I type just 

su

It asks for the root user password. But both the commands directs me to the root terminal. Then why is there such a difference?

Anonymous Platypus
  • 3,730
  • 10
  • 33
  • 51
  • 1
    @muru The OP is asking difference between `su` and `sudo su` not `sudo -s` or `sudo -s` – Maythux May 08 '15 at 07:58
  • 2
    @NewUSer read again. – muru May 08 '15 at 07:59
  • 1
    There is never a good reason to run `sudo su`. I've always wondered why this is so commonly suggested in the Ubuntu world. It is clumsy, inelegant and adds needless overhead. Just run `su` if you've set up the root account or `sudo -i` if you haven't. `sudo su` is just silly. – terdon May 08 '15 at 08:43
  • 1
    @terdon Usually when the user is on a corporate LAN the system administrators may not share the root user password with all the employees. In such a scenario its easier for a user to become root by putting `sudo su` and inserting user password. Since majority of Linux users are workers under corporates, say IT, I guess this could be a reason. :) – Anonymous Platypus May 08 '15 at 09:16
  • 1
    @AnonymousPlatypus no, that's when you use `sudo -i`, or `sudo -s`, you might also want to use `-E`, depending on what you want to do. What you don't want is `sudo su`. Both because there's no reason to run two programs when one is enough and because that way you can control the resulting environment much better. – terdon May 08 '15 at 09:27

1 Answers1

19

sudo su means run the command su as sudo which means as root. Here the system will ask you for your password since you are a sudoer. After you enter your password, you now have root privileges. So su command won't ask for a password. It's same as if you are a root then su to any other user will not ask for password because you are a root.

When you just run the command su, you are running it as a regular user. Since su means switch to user root, you will be asked for the root password.

Community
  • 1
Maythux
  • 82,867
  • 54
  • 239
  • 271
  • 2
    This is a good answer so I wont write another but would like to include the following detailed blog post I found http://johnkpaul.tumblr.com/post/19841381351/su-vs-sudo-su-vs-sudo-u-i – Mark Kirby May 08 '15 at 08:01