bash autocomplete bash-completion compgen

Simulate Bash's COMPREPLY response without actually completing it

Steps to reproduce

Create directory on tmp, add 1 file inside.

mkdir /tmp/testdir && touch /tmp/testdir/examplefile

Paste below script on /tmp/completion.sh

# BEGIN AUTOCOMPLETE
function _foo_complete() {
local comnum cur opts
[[ "${COMP_WORDS[@]}" == *"-"* ]] && comnum=2 || comnum=1;
COMPREPLY=()
cur="${COMP_WORDS[COMP_CWORD]}"
opts="--help --restart -h -r"
if (( COMP_CWORD > comnum )); then
 COMPREPLY=( $(for filename in "/tmp/testdir/"*; do echo ${filename##*/}; done) )
 return
fi
if [[ ${cur} == -* ]]; then
 COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
 return 0
else
 COMPREPLY=( $(for filelist in /tmp/testdir/"$2"*; do echo ${filelist##*/}; done) )
fi
}
complete -F _foo_complete foo.sh
# END AUTOCOMPLETE

Source it then.
```
. /tmp/completion.sh
```

Expected result

$ foo.sh --restart examplefile <tab><tab>
examplefile           
$ foo.sh --restart examplefile <tab><tab>
examplefile        
$ foo.sh --restart examplefile <tab><tab>
examplefile     
$ foo.sh --restart examplefile <tab><tab>

What happen instead

$ foo.sh --restart examplefile <tab><tab> examplefile <tab><tab> examplefile <tab><tab> examplefile <tab><tab> examplefile <tab><tab> examplefile

I want the suggestion to appear as possible completion, but without actually completing it (for display purposes). This question has been asked before, but to this date no answer is given.

Regarding `-o nosort`

I look into that option and it's only available at Bash 4.4+, I tried on my 16.04 machine and it fail. Looking for more globalish solution

Solution

Try the following compspec.sh (based on OP's code):

function _foo_complete()
{
    local comnum cur opts

    [[ "${COMP_WORDS[@]}" == *"-"* ]] && comnum=2 || comnum=1;

    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    opts="--help --restart -h -r"

    if (( COMP_CWORD > comnum )); then
        COMPREPLY=( $(for filename in "/tmp/testdir/"*; do echo ${filename##*/}; done) )
        if [[ ${#COMPREPLY[@]} -gt 0 ]]; then
            #
            # you can try COMPREPLY+=( zzz ) and see what's happening
            #
            COMPREPLY+=( ' ' )
        fi
        return
    fi

    if [[ ${cur} == -* ]]; then
        COMPREPLY=( $( compgen -W "${opts}" -- ${cur} ) )
        return 0
    else
        COMPREPLY=( $( for filelist in /tmp/testdir/"$2"*; do echo ${filelist##*/}; done ) )
    fi
}

complete -F _foo_complete foo.sh

enter image description here

UPDATE:

is it possible to move the empty string to end of completion, so it doesn't look like there are empty space?

You can use complete -o nosort ^{(requires Bash 4.4+)} if you can sort the completion candidates all by yourself.