How to complete filenames relative to another directory?

Question

This is a follow-up question to the discussion in:

https://bugs.launchpad.net/ubuntu/+source/bash-completion/+bug/1394920

Suppose I have a folder ~/tmp with some files and directories:

$ mkdir a; touch file1.txt; mkdir a/b; mkdir a/c; touch a/d; mkdir a/b/c

I now try to make a completion script to complete filenames in ~/tmp, but the complete -o filenames option is only working correctly if the current directory is ~/tmp.

See the above link for more background information. This is as far as I got:

$ cat setup
_compTest() {
    local cur baseFolder
    cur="${COMP_WORDS[$COMP_CWORD]}"
    baseFolder=~/tmp
    compopt -o nospace
    COMPREPLY=(  $(
       cd "$baseFolder"
       if [[ ${cur: -1} != "/" && -d $cur ]] ; then
           echo "$cur/"
       else
           compgen -f "$cur"
       fi
      )  )
}
complete -F _compTest aaa

Then I source it:

$ . setup

and I can then do

$ aaa <tab><tab>

• Problem 1 : Slashes are not added at the end of directory names in the completion list ( this is desired to easy separate directories from file names in the completion list)

• Problem 2 : For aaa a/<tab><tab> the completion list is a/b a/c a/d but the a/ prefix should not be there. It should be b/ c/ d instead.

Answer 1

I would write this function as:

_compTest () 
{ 
    local cur; local tmp;  local tmp_escaped; local i;
    _get_comp_words_by_ref cur;
    local _compreply=()
    tmp=~/tmp/
    tmp_escaped=${tmp//\//\\\/}
    cur=$tmp$cur;

    if [ "$1" == "-d" ]; then
        _cd
    else
        _filedir;
    fi;
    for i in "${COMPREPLY[@]}"; do
        [ -d "$i" ] && [ "$i" != "$tmp." ] && [ "$i" != "$tmp.." ] && i="$i/"
        _compreply=("${_compreply[@]}" "$i")
    done

    COMPREPLY=(${_compreply[@]/$tmp_escaped/})
} && complete -o nospace -F _compTest aaa_files

_compTestDir()
{
    _compTest -d
} && complete -o nospace -F _compTestDir aaa_directories

It has 3 parts,

1. prefixing the $cur with your base directory - ~/tmp.
2. Using standard bash completion routine _filedir used for cd/ls etc.
3. Removing ~/tmp from COMPREPLY

Just for the record: You can use this logic to complete the file names relative to many other types of path, e.g.

1. I use it to complete perforce paths //....
2. You can also complete http://localhost/* paths, relative to your public_html directory.

Answer 2

Would have added as a comment, but I don't have the reputation...

Building on @anishsane's answer, if there is only a single completion option and it is not a directory, then you may not want to include the nospace option. For example, the program may accept another argument after the one you are currently completing. If there is only one option, we should accept that option and move on to the next arg.

To do this, remove nospace from the complete line and add logic to enable nospace only when needed:

    # [...]

    # Do not include trailing space in results if there is more than one option
    # or if the only option is a directory
    [ "${#_compreply[@]}" -gt 1 ] && compopt -o nospace
    [ "${#_compreply[@]}" -eq 1 ] && [ -d "${_compreply[0]}" ] && compopt -o nospace

    COMPREPLY=(${_compreply[@]/$tmp_escaped/})
} && complete -F _compTest aaa_files