Properly handling spaces and quotes in bash completion

Question

What is the correct/best way of handling spaces and quotes in bash completion?

Here’s a simple example. I have a command called words (e.g., a dictionar

Answer 1

This not too elegant postprocessing solution seems to work for me (GNU bash, version 3.1.17(6)-release (i686-pc-cygwin)). (Unless I didn't test some border case as usual :))

Don't need to eval things, there are only 2 kinds of quotes.

Since compgen doesn't want to escape spaces for us, we will escape them ourselves (only if word didn't start with a quote). This has a side effect of full list (on double tab) having escaped values as well. Not sure if that's good or not, since ls doesn't do it...

EDIT: Fixed to handle single and double qoutes inside the words. Essentially we have to pass 3 unescapings :). First for grep, second for compgen, and last for words command itself when autocompletion is done.

_find_words()
{
    search=$(eval echo "$cur" 2>/dev/null || eval echo "$cur'" 2>/dev/null || eval echo "$cur\"" 2>/dev/null || "")
    grep -- "^$search" words.dat | sed -e "{" -e 's#\\#\\\\#g' -e "s#'#\\\'#g" -e 's#"#\\\"#g' -e "}"
}

_words_complete()
{
    local IFS=$'\n'

    COMPREPLY=()
    local cur="${COMP_WORDS[COMP_CWORD]}"

    COMPREPLY=( $( compgen -W "$(_find_words)" -- "$cur" ) )

    local escaped_single_qoute="'\''"
    local i=0
    for entry in ${COMPREPLY[*]}
    do
        if [[ "${cur:0:1}" == "'" ]] 
        then
            # started with single quote, escaping only other single quotes
            # [']bla'bla"bla\bla bla --> [']bla'\''bla"bla\bla bla
            COMPREPLY[$i]="${entry//\'/${escaped_single_qoute}}" 
        elif [[ "${cur:0:1}" == "\"" ]] 
        then
            # started with double quote, escaping all double quotes and all backslashes
            # ["]bla'bla"bla\bla bla --> ["]bla'bla\"bla\\bla bla
            entry="${entry//\\/\\\\}" 
            COMPREPLY[$i]="${entry//\"/\\\"}" 
        else 
            # no quotes in front, escaping _everything_
            # [ ]bla'bla"bla\bla bla --> [ ]bla\'bla\"bla\\bla\ bla
            entry="${entry//\\/\\\\}" 
            entry="${entry//\'/\'}" 
            entry="${entry//\"/\\\"}" 
            COMPREPLY[$i]="${entry// /\\ }"
        fi
        (( i++ ))
    done
}