Add documentation for installing rustup completion as non root user

[ArifRoktim]

The instructions for adding rustup completion for bash as a non root
user were missing. Said instructions were already added for the other
shells.

[tesuji]

Strange, this instruction didn't work on my machine.

$ bash --version
GNU bash, version 4.4.19(1)-release (x86_64-pc-linux-gnu)

[ArifRoktim]

Hmm, it works for me when I copy and paste the two commands as-is. I tested it on Fedora 29 and Ubuntu 18.04.2 LTS. The bash version on Ubuntu is the same as yours:

GNU bash, version 4.4.19(1)-release (x86_64-pc-linux-gnu)

Troubleshooting steps:

• Do you have the bash-completion package installed and working?
  • Does your shell source /etc/profile in ~/.bashrc?
  • Did you apply any manual modifications to /etc/profile, the files in /etc/profile.d, or the files in /usr/share/bash-completion/?
• Do you have either of the following environment variables set?
  • $BASH_COMPLETION_USER_DIR
    • Defaults to $XDG_DATA_HOME/bash-completion when not set
  • $XDG_DATA_HOME
    • Defaults to ~/.local/share/ when not set

Also, what OS/Linux distro are you using?

[tesuji]

@ArifRoktim It's my fault for not sourcing /etc/bash_completion in ~/.bashrc.
Maybe you could add that caution in this PR.

It is weird! Last time I used bash interactively, I don't need to source /etc/bash_completion.
In /etc/skel/.bashrc, it states that

# 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 ! 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
  fi
fi

But in /etc/bash.bashrc, those lines has been commented:

# 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
#  fi
#fi

I'm on Ubuntu 18.04.2 (fresh install).

[ArifRoktim]

@lzutao So I spun up a fresh install of Ubuntu in a VM to see if bash completion works by default. After running the rustup completions ... command and opening a new shell, rustup completion worked.

I looked at the default shell config files and at the very end of ~/.bashrc(and also /etc/skel/.bashrc) were the following lines:

# 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 ! 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
  fi
fi

I took a look at /etc/bash.bashrc and also found those commented out lines. I guess Ubuntu decided that it's better to have the completion-enabling code in the user .bashrc to make it easier for users to turn off the feature if they wanted to.
Fedora takes a different approach. The default .bashrc just sources /etc/bashrc. That file then sources all files that fit the glob /etc/profile.d/*.sh, and /etc/profile.d/bash_completion.sh matches that glob.

---

I think in general, bash completion usually "just works" out of the box for most Linux distros. The exact method that the shell uses to enable bash completion is distro specific. Perhaps I should add that users should first check to make sure that completion works for their specific shell?

[bors]

☔ The latest upstream changes (presumably #1704) made this pull request unmergeable. Please resolve the merge conflicts.

[kinnison]

Hi @ArifRoktim

Would you mind rebasing your change rather than having a PR with merge commits in?

I think that if you do that, we should be in a position to merge this pretty soon.

Thanks,

D.

[bors]

☔ The latest upstream changes (presumably #1646) made this pull request unmergeable. Please resolve the merge conflicts.

[kinnison]

Hi @ArifRoktim

I merged some changes which put you in need of a rebase again. Since it was in part my fault for taking so long to process your PR I've rebased it for you and think it's good. Could you please check what I've done and if it's good then we'll try and merge your submission :D

D.

[yodaldevoid]

I might have already covered this with #1646. If I overshadowed your work, I'm sorry.

[ArifRoktim]

@yodaldevoid
Indeed you have. But it's fine, these things happen.
I've also been annoyed by not having cargo completion for a while so I'm happy for your pr being merged 😄

@kinnison
There are some issues with the rebase but since #1646 obsoletes this pr, I'm going to close it instead. Thanks for working with me on this pr even if it is closed.