bash autocomplete feature doesn't work when I create function for emacs

Question

Details about my system: I am running Ubuntu 12.04.4 LTS on Oracle Virtual Box 4.3.6, from Windows 8.1 installed on an Asus Laptop. I'm using bash_completion version 1.3 release (I got this from the comments on the /etc/bash_completion file)

I thought bash always did auto complete for files and directories after a command. But after a google search and reading more about the bash_completion thing, I realized that this was different for different commands. But I'm facing a problem with this auto-completion feature of bash when using an alternate way to invoke emacs -nw.

I have defined ee as a function in my ~/.bash_aliases file. I know this is not an alias, but I am just using a function to do what an alias would do:

function ee () {
    emacs -nw "$@"
}

export -f ee

I thought that I could still use tab completion with the ee function if I typed a partial file name. This just doesn't seem to work. Whereas if I typed in emacs -nw followed by a partial file name the tab completion works perfectly. I really don't understand what is missing here. I checked the output of the command complete -p and I get the following for both emacs and ee:

eakangk@eakan-u-vbox:~$ complete -p | grep 'ee'
complete -F _filedir_xspec ee
eakangk@eakan-u-vbox:~$ complete -p | grep 'emacs'
complete -F _filedir_xspec emacs

Wouldn't that mean both commands should give me the same sort of behaviour when attempting auto completion? Edit: I hadn't seen the ee line in the /etc/bash_completion file when posting the question. But now I know it is there. But the /etc/bash_completion file has the following lines:

complete -f -X '!*.@(gif|jp?(e)g|miff|tif?(f)|pn[gm]|p[bgp]m|bmp|xpm|ico|xwd|tga|pcx)' ee
complete -f -X '*.@(o|so|so.!(conf)|a|[rs]pm|gif|jp?(e)g|mp3|mp?(e)g|avi|asf|ogg|class)' vi vim gvim rvim view rview rgvim rgview gview emacs xemacs sxemacs kate kwrite

What am I doing wrong here?

Answer 1

This has to do with the bash-completion package. It has some custom completion set for emacs, and apparently that same completion fails when the command name is different.

I don't use bash-completion myself, but I did a quick look at the source, and found this:

_install_xspec '*.@(o|so|so.!(conf|*/*)|a|[rs]pm|gif|jp?(e)g|mp3|mp?(e)g|avi|asf|ogg|class)' vi vim gvim rvim view rview rgvim rgview gview emacs xemacs sxemacs kate kwrite

which is probably used to say "for these commands, do not complete files ending with .gif, .mp3, .avi etc", and I'm guessing that if there's no _install_xspec line for your ee command, it doesn't complete anything.

Looking at the _install_xspec function, it simply puts these values in an associative array named _xspecs using command name as key, so if you run, _xspecs[ee]=${_xspecs[emacs]}, the ee command should get the same completions as emacs gets.