Ask Ubuntu is a question and answer site for Ubuntu users and developers. It's 100% free.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I'm new to Ubuntu 12.04 LTS. My problem is described below.

My terminal prompt is the $ sign only. It's not showing like kaushik-kaushik-pc -$.

My second problem is that when I try to become the super user by sudo su, it prompts for my password but after that, it shows Authentication Fail.

When I'm trying to use previous commands by using the key, it prints this ^[[a, nor does it work for the or keys.

share|improve this question
I have also experienced that but in a guest account, check to make sure you are using an account with privilege. – tmwanik Mar 3 '13 at 11:34
Welcome to Ask Ubuntu! It is preferred if you can post separate questions instead of combining your questions into one. That way, it helps the people answering your question and also others hunting for atleast one of your questions. Thanks! – guntbert Mar 3 '13 at 19:07
We need more information: please edit your question and show us the output of id. – guntbert Mar 4 '13 at 20:29
up vote 1 down vote accepted

I am answering only the authentication question.

sudo su is completely unnecessary.

For a single command (like cat /etc/shadow) you just type sudo cat /etc/shadow and then you give your own password. This will by default only be possible for the first user (the one created during installation).

If you are really convinced that you need a real root shell then type sudo -i, run the commands you need and don't forget to leave that shell again by pressing CTRLD.

share|improve this answer
When i'm typing 'sudo -i' it is giving an error message: sudo: /bin/bash: command not found. – Kaushik Kishore Mar 4 '13 at 8:19

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.