tags.sh

# Pure bash solution to lit, add and remove tags for files in OS X
# Based on https://apple.stackexchange.com/a/119370
# Depends on xattr (https://github.com/xattr/xattr - included in OS X?)
# Alternative: https://github.com/jdberry/tag

# Add the followingꜜ to your .bashrc

#tags <file>
#Lists all tags of a file

#tags -add <tag> <file>
#Adds tag to a file

#tags -remove <file>
#Removes all tags from a file

#TODO:
# - remove specific tag

tags() {
    # tags system explained: http://arstechnica.com/apple/2013/10/os-x-10-9/9/
    local src=$1
    local action="get"

    if [[ $src == "-remove" ]]; then
        src=$2
        local action="remove"
    fi

    if [[ $src == "-add" ]]; then
        src=$3
        local newtag=$2
        local action="add"
    fi

    # hex -> bin -> json -> lines
    local hexToLines="xxd -r -p - - | plutil -convert json -o - - | sed 's/[][]//g' | tr ',' '\n'"

    # lines -> json -> bin -> hex
    local linesToHex="tr '\n' ',' | echo [\$(sed 's/,$//')] | plutil -convert binary1 -o - - | xxd -p - -"

    local gettags="xattr -px com.apple.metadata:_kMDItemUserTags \"$src\" 2> /dev/null | $hexToLines | sed 's/.*Property List error.*//'"

    # echo $action
    if [[ $action == "get" ]]; then
        sh -c "$gettags"
    elif [[ $action == "remove" ]]; then
        local write="xattr -d com.apple.metadata:_kMDItemUserTags \"$src\""
        sh -c "$write"
    else
        local add="(cat -; echo \\\"$newtag\\\") | sort -u"
        local write="xattr -wx com.apple.metadata:_kMDItemUserTags \"\$($gettags | $add | grep . | $linesToHex)\" \"$src\""

        sh -c "$write"
    fi
}
export -f tags