How to complete a bash function with multiple parameters/options?

Question

I defined a function alias for a command: aa and I defined a _complete_aa function which is used as a suggestion for the aa command via complete -F _complete_aa aa (See code below)

aa(){
    anothercommand ${@}
}

_complete_aa(){
    COMPREPLY=($(compgen -W "clean build start" "${COMP_WORDS[1]}"))
}

complete -F _complete_aa aa

When I use the function I have an unexpected behavior:

When I type aa cle and press TAB the prompt correctly completes my input into aa clean

But, when I type aa clean bui and press TAB, the prompt completes my inuput into aa clean clean, while I expect it should change into aa clean build.

I guess my error is in the below completion function, Which does not take care of the index of the current word under completion.

_complete_aa(){
    COMPREPLY=($(compgen -W "clean build start" "${COMP_WORDS[1]}"))
}

Question: how I should change the body of the _complete_aa function so that I get completion of the current word into clean build start for each new option/parameter I am typing ?

Benjamin W. · Accepted Answer · 2020-02-25 14:08:17Z

1

The completion function gets positional parameters, of which $2 is the "word being completed", so you could do this:

_complete_aa(){
    COMPREPLY=($(compgen -W "clean build start" "$2"))
}

If your completion really is just the selection of given words, you can use the simpler -W completion instead:

complete -W 'clean build start' aa

answered Feb 25, 2020 at 14:08

Benjamin W.

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1 Comment

psuzzi Over a year ago

Awesome. Clear explaination, and both the proposed solutions works. Thanks!

KamilCuk · Accepted Answer · 2020-02-25 14:05:05Z

1

Index COMP_WORDS with current word index.

aa() {
    anothercommand "$@"
}

_complete_aa() {
    COMPREPLY=($(compgen -W "clean build start" "${COMP_WORDS[$COMP_CWORD]}"))
}

complete -F _complete_aa aa

The "${COMP_WORDS[1]}" is always going to be the first word after the command.

answered Feb 25, 2020 at 14:05

KamilCuk

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1 Comment

psuzzi Over a year ago

Also this solution works. This solution goes more in the details, and it is more useful in case one wants to write a complex function that deals with the current position of the word.

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