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I have just came across something that is really bothering me. Autocompletion on ubuntu works like a charm but when I login as root, e.g. su I get tab autocompletion only sometimes.

Why does it work like that? Can one change that?

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Are you actually logging in as root, or using sudo su? – Marty Fried Feb 12 '12 at 19:08
@MartyFried Yes I am diong sudo su. What is the difference? – Patryk Feb 12 '12 at 19:19
It seems to work for me, can you provide us with a specific instance of when it does not work, something that we can replicate. – ste_kwr Feb 12 '12 at 20:20
@lordmonkey: Maybe none, I'm not really sure. I think su or sudo su by itself is a little different in some way that I don't remember, so I wanted to make sure that I could check this under the same conditions. It seems like it works, but you said "sometimes", so I can only suggest you double-check and try to make it reproducible, or just make sure there's not something else happening that is fooling you - ie, user error - hey, it happens to everyone! :) – Marty Fried Feb 12 '12 at 20:48
up vote 17 down vote accepted

Check your /root/.bashrc file for these lines

if [ -f /etc/bash_completion ]; then
  . /etc/bash_completion

If they do not exist add them to the end of the file using your favorite text editor.

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Mine .bashrc contained the mentioned lines but they were commented out; uncommented the lines and sourced the new .bashrc ; things look pretty good now . – Ankit Jul 10 '12 at 2:30

You haven't mentioned which Ubuntu version you use.

  • Check if you have the bash-completion package installed:

    sudo apt-get install bash-completion
  • Mine works if I login using: sudo -i

share|improve this answer
What's the point of removing root's .bashrc? – geirha Jun 27 '12 at 11:09
I think it will regenerate the default .bashrc upon next logout/login. Or perhaps it could contain some kind of "deactivation" for autocompletion (don't know if it's possible). I can't remember the actual reason I wrote it down though. – medigeek Jun 27 '12 at 13:23
No, a new .bashrc will not be created, and /etc/bash_completion will not be sourced, only bash's default completion will be available. – geirha Jun 27 '12 at 13:35
OK, edited and removed. Thank you for your input! Though I wonder if ~/.bashrc can "unsource" a file or if disable-completion is still available:… – medigeek Jun 28 '12 at 4:34

For Ubuntu 13.10, check /etc/bash.bashrc for

# enable bash completion in interactive shells
if ! shopt -oq posix; then
  if [ -f /usr/share/bash-completion/bash_completion ]; then
    . /usr/share/bash-completion/bash_completion
  elif [ -f /etc/bash_completion ]; then
    . /etc/bash_completion

They might be commented. Un-commenting them works.

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Found that this worked (similar to the answers above but with a twist)

The file that needs to be edited (at least in my case with 12.04) was /root/.bashrc. This makes sense in my case, given that my regular user was autocompleting just fine but my root wasn't.

Anyway in said file I found all the necessary code but it was commented out:

# enable programmable completion features (you don't need to enable
# this, if it's already enabled in /etc/bash.bashrc and /etc/profile
# sources /etc/bash.bashrc).
#if [ -f /etc/bash_completion ] && ! shopt -oq posix; then
    #. /etc/bash_completion

Just un-commented it:

# enable programmable completion features (you don't need to enable
# this, if it's already enabled in /etc/bash.bashrc and /etc/profile
# sources /etc/bash.bashrc).
if [ -f /etc/bash_completion ] && ! shopt -oq posix; then
    . /etc/bash_completion

Saved, and it worked just fine.

Hope this helps someone.

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