Bash completion: command not found

[blahgeek]

I'm using xonsh 0.4.5 on OS X, with bash-completion 1.3 installed with homebrew.

My $BASH_COMPLETIONS is set to ['/usr/local/etc/bash_completion'], but bash completion does not working. So I looked at the code at completers/bash.py and tested the following code:

bash -c 'source "/usr/local/etc/bash_completion.d/ssh"\nCOMP_WORDS=(ssh M)\nCOMP_LINE=\'ssh M\'\nCOMP_POINT=${#COMP_LINE}\nCOMP_COUNT=6\nCOMP_CWORD=1\n_ssh ssh M ssh\nfor ((i=0;i<${#COMPREPLY[*]};i++)) do echo ${COMPREPLY[i]}; done\n'
/usr/local/etc/bash_completion.d/ssh: line 3: have: command not found
/bin/bash: line 6: _ssh: command not found

The have command in bash_completion.d/ssh is defined in bash_completion which is not loaded. I also checked bash-completion 2.3.5 in archlinux, its completions/ssh also uses some functions like _init_completion in bash_completion.

I have source /usr/local/etc/bash_completion in my .bashrc but it wont load while running bash by bash -c.

Did I do anything wrong or it may be a bug? Thanks!

[scopatz]

I don't think that you are doing anything wrong. I think it is just that you completions may be out of date. If I look at the defintion of have() on my Ubuntu box, I see:

# Backwards compatibility for compat completions that use have().
# @deprecated should no longer be used; generally not needed with dynamically
#             loaded completions, and _have is suitable for runtime use.
have()
{
    unset -v have
    _have $1 && have=yes
}

However, we could modify our bash completer to also source the /usr/local/etc/bash_completion first too. Basically, we'd look for a bash_completion file in the corresponding directory and that to the source command. Would you be willing to take a stab at that @blahgeek?

[blahgeek]

Thanks for your reply~

Yes the completions installed by homebrew is a little bit outdated. But still, if I ran that command on my linux box (with bash-completion 2.3.5 installed), it prints:

/usr/share/bash-completion/completions/ssh: line 158: _init_completion: command not found

It seems that, one way or another, individual completion scripts will depend on the "main" script bash_completion.

I thought about fixing this issue by sourcing the bash_completion first in complete_from_bash function, but then I realized that may not be a good idea, since bash_completion loads all scripts under bash_completion.d and can take quite a while.

A good way to fix this can be modifying complete_from_bash to maintain a long-running background bash process, so it only loads all the scripts at startup and we can use pipes to get completions from it. Though it will need a almost complete rewrite of completers/bash.py.

Any ideas? @scopatz

[scopatz]

bash_completion loads all scripts under bash_completion.d and can take quite a while

Yeah, how slow is it though really? Do you have any timings?

A good way to fix this can be modifying complete_from_bash to maintain a long-running background bash process, so it only loads all the scripts at startup and we can use pipes to get completions from it. Though it will need a almost complete rewrite of completers/bash.py

I think that this would be too fragile, personally. It also seems excessive for their to be a bash process open for every xonsh process in practice.

If loading all the scripts really is too slow (and I can see how it would be), I think a better strategy would be:

1. the first time we load all the completers via bash_completion, we also grab the source code for all of the bash functions in the bash_completion file. Bash does make this relatively easy to do. We store these in some internal cache.
2. When a completer is executed, we glue the function definitions from bash_completion into the script we are going to run prior to the `source "completer/file.sh" call.

This would make sure that those functions are available. Alternatively, we could

1. have an internal copy of bash_completion with just the function defs that xonsh always prepends, or
2. figure out a ways to dynamically comment out the completer loading in bash_completion prior to sourcing it directly.

I'd be pretty happy with an implementation of any of the above strategies.

[blahgeek]

How about that?

I set BASH_COMPLETION_DIR and BASH_COMPLETION_COMPAT_DIR to prevent bash_completion to loading every scripts in completions.d

[scopatz]

I set BASH_COMPLETION_DIR and BASH_COMPLETION_COMPAT_DIR to prevent bash_completion to loading every scripts in completions.d

Awesome!