Bash auto completion script

autocompletebash

I'm trying to setup autocompletion for a command, which takes only one parameter, a folder name,

In /secure/kernel_builds/, I have the three following subfolder:

3.5.6/ 3.6.2/ source/

Now I want auto completion, that lists all sub folder name possible, but not the one named source, right now I'm using a pretty stupid way to do it, by checking if the completion word is started with a number,

_avail_kernel_builds()
{
    case $COMP_CWORD in
        1)
            if [[ "${COMP_WORDS[COMP_CWORD]}" =~ ^[0-9] ]];then
                COMPREPLY=( /secure/kernel_builds/"${COMP_WORDS[COMP_CWORD]}"* )
            else
                COMPREPLY=( /secure/kernel_builds/"${COMP_WORDS[COMP_CWORD]}"[0-9]*/ )
            fi
            COMPREPLY=( "${COMPREPLY[@]#/secure/kernel_builds/}" )
            COMPREPLY=( "${COMPREPLY[@]%/}" )
            ;;
    esac    
}

Is there a better way of doing so?

Best Answer

The compgen builtin has a -X argument for this very purpose:

-X filterpat
    filterpat is a pattern as used for filename expansion. It is applied to the list of 
    possible completions generated by the preceding options and arguments, and each 
    completion matching filterpat is removed from the list. A leading ! in filterpat 
    negates the pattern; in this case, any completion not matching filterpat is removed.

So you could probably just do something like:

_avail_kernel_builds() {
    case $COMP_CWORD in
        1) COMPREPLY=( $(cd /secure/kernel_builds; compgen -d -X "source") ) ;;
    esac
 }

So compgen -d says "list the folders in the current directory", and -X "source" says "...but filter out anything named "source".

Related Solutions

Add arguments from previous command to zsh completion

You can add your completer to the list of completers used by default:

zstyle ':completion:*' completer _last_command_args _complete

Bash – Custom autocomplete: deal with spaces in filenames

Believe it might be better to use compgen instead of find in this case.

You probably already have a completion script with system. Try e.g.

locate bash_completion

On Debian variants this is probably:

/usr/share/bash-completion/bash_completion

where you find e.g. _filedir. So the simplest way then would be something in the direction of:

*)
    pushd "/some/path" >/dev/null
    _filedir
    popd >/dev/null

If that is not an option this could be a starter:

_comp_by_path()
{
    local opt cur dir
    local IFS=$'\n' x tmp
    local -a tokens

    opt="$1"
    cur="$2"
    dir="$3"

    # Enter target directory
    pushd "$dir" >/dev/null

    # Get directories, filtered against current
    [[ "$opt" != "-f" ]] && \
    x=$( compgen -d -- "$cur" ) &&
    while read -r tmp; do
        tokens+=( "$tmp" )
    done <<< "$x"

    # Get files, filtered against current
    [[ "$opt" != "-d" ]] && \
    x=$( compgen -f -- "$cur" ) &&
    while read -r tmp; do
        tokens+=( "$tmp" )
    done <<< "$x"

    # If anything found
    if [[ ${#tokens[@]} -ne 0 ]]; then
        # Make sure escaping is OK
        compopt -o filenames 2>/dev/null
        COMPREPLY+=( "${tokens[@]}" )
    fi

    # Go back
    popd >/dev/null
}

_GetOptMyCommand()
{
    local cur

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

    case "$cur" in
    -*)
        COMPREPLY=( $( compgen -W "-h -l --help --list --" -- "$cur" ) );;
    *)
        _comp_by_path "any" "$cur" "/some/path"
    esac
}

complete -F _GetOptMyCommand my_command

A variant using find could be something in direction of this:

_zaso()
{
    local dir="$1"

    pushd "$dir" >/dev/null
    find * -maxdepth 0 2>/dev/null
    popd >/dev/null
}

_comp_with_find()
{
    local cur dir      
    local IFS=$'\n'

    cur="$1"
    dir="$2"

    compopt -o filenames 2>/dev/null
    COMPREPLY=( $( compgen -W "$(_zaso "$dir")" -- "$cur" ) );
}

Also note that printf in Bash has a %q option. So to generate quoted strings this is an option to play with:

find * -maxdepth 0 2>/dev/null && \
while read -r tmp; do
    printf "%q\n" "$tmp"
done <<< "$x"

Also not that file names can have newline characters in which a lot of this will break. Have not found a way to use \0 with compgen.

Best Answer

Related Solutions

Add arguments from previous command to zsh completion

Bash – Custom autocomplete: deal with spaces in filenames

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