Custom bash tab completion

Question

I have my custom console utility cooltool with list of options

fooOption
barOption

What should I do to able bash autocomplete the options by pressing the tab key?

I mean the user typed

$ ./cooltool foo_

then pressed tab. And then

$ ./cooltool fooOption _

appeared.

Answer 1

Write a bash completion script for cooltool. The bash-completion package comes with scripts for many popular programs, which you can use as examples.

Answer 2

The simplest way is to add the following to your .bashrc.

_cooltool()
{
    local cur=${COMP_WORDS[COMP_CWORD]}
    COMPREPLY=( $(compgen -W "fooOption barOption" -- $cur) )
}
complete -F _cooltool cooltool

Whenever you type cooltool f[TAB][TAB], the _cooltool() function is invoked. It will work out what your current partial word is and then compgen will work out which options match. These are stored in an array called COMPREPLY which is then displayed. Look at man complete and man compgen for details.

For a nice tutorial check out: Writing your own Bash Completion Function

Answer 3

You might want to take a closer look inside your /etc/bash_completion.d directory on your system.

Also you should read this introduction. The second part of the introduction is the one you need.

Answer 4

Here is the code that is used for git bash completion

Answer 5

In addition to dogbane's answer, you could also do:

complete -W "fooOption barOption" cooltool

if you simply want to match a list of words from the beginning of the string. It seems that complete and compgen share most options. I've only noticed "beginning of string" matching in the commands I use, so I found it neat that you can do other things in the _cooltool function like:

COMPREPLY=( $(grep "$cur" ~/my_potential_args.txt) )

to match anywhere in the option name.