Using bash functions under sudo

Update: Now on github

Have you ever done the following?

$ type duk
duk is a function
duk ()
{
   du -k "$@" | sort -n
}

$ sudo duk /tmp
sudo: duk: command not found

duk is a function that will show you directory sizes under a given pathname (or the current directory), nicely sorted by size, largest at the bottom just above your next prompt. It's very handy, put it in your .bashrc ;-). sudo doesn't know what to do with "duk" however, since it's not a system command. Therefore, I wrote a function that is a front-end to sudo. It parses the command line you give it, and expands any functions or aliases that you call. For bonus points, it shows you the full command line as the shell receives it before you type your password. Use it as follows:

$ source sudo.bash
$ sudo duk /tmp
/opt/local/bin/sudo -- bash -x -v -c duk ()
{
   du -k "$@" | sort -n
};"duk" '/tmp'
Password:

[...]

3648    /tmp/synergy-1.3.1/lib
6184    /tmp/synergy-1.3.1
20128   /tmp/prarora
1294048 /tmp/tmp
5304016 /tmp

Looks like I'll need to do some cleaning up in /tmp. Full source follows. To use it, place a source ~/.sudo.bash (for example) in your .bashrc after copying the code to your ~/.sudo.bash, or copy the full code to your .bashrc. Then, simply use sudo as you would before. This function handles all sudo arguments. There is one extra argument, -x, which expands arguments as you, not as root. This is needed in some corner cases. (Update: New version which no longer uses sed and handles spaces in sudo options!)

# Wrap sudo to handle aliases and functions
# Wout.Mertens@gmail.com
#
# Accepts -x as well as regular sudo options: this expands variables as you not root
#
# Comments and improvements welcome
#
# Installing: source this from your .bashrc and set alias sudo=sudowrap
#  You can also wrap it in a script that changes your terminal color, like so:
#  function setclr() {
#    local t=0               
#    SetTerminalStyle $1                
#    shift
#    "$@"
#    t=$?
#    SetTerminalStyle default
#    return $t
#  }
#  alias sudo="setclr sudo sudowrap"
#  If SetTerminalStyle is a program that interfaces with your terminal to set its
#  color.

# Note: This script only handles one layer of aliases/functions.

# If you prefer to call this function sudo, uncomment the following
# line which will make sure it can be called that
#typeset -f sudo >/dev/null && unset sudo

sudowrap () 
{
    local c="" t="" parse=""
    local -a opt
    #parse sudo args
    OPTIND=1
    i=0
    while getopts xVhlLvkKsHPSb:p:c:a:u: t; do
        if [ "$t" = x ]; then
            parse=true
        else
            opt[$i]="-$t"
            let i++
            if [ "$OPTARG" ]; then
                opt[$i]="$OPTARG"
                let i++
            fi
        fi
    done
    shift $(( $OPTIND - 1 ))
    if [ $# -ge 1 ]; then
        c="$1";
        shift;
        case $(type -t "$c") in 
        "")
            echo No such command "$c"
            return 127
            ;;
        alias)
            c="$(type "$c")"
            # Strip "... is aliased to `...'"
            c="${c#*\`}"
            c="${c%\'}"
            ;;
        function)
            c="$(type "$c")"
            # Strip first line
            c="${c#* is a function}"
            c="$c;\"$c\""
            ;;
        *)
            c="\"$c\""
            ;;
        esac
        if [ -n "$parse" ]; then
            # Quote the rest once, so it gets processed by bash.
            # Done this way so variables can get expanded.
            while [ -n "$1" ]; do
                c="$c \"$1\""
                shift
            done
        else
            # Otherwise, quote the arguments. The echo gets an extra
            # space to prevent echo from parsing arguments like -n
            while [ -n "$1" ]; do
                t="${1//\'/\'\\\'\'}"
                c="$c '$t'"
                shift
            done
        fi
        echo sudo "${opt[@]}" -- bash -xvc \""$c"\" >&2
        command sudo "${opt[@]}" bash -xvc "$c"
    else
        echo sudo "${opt[@]}" >&2
        command sudo "${opt[@]}"
    fi
}
# Allow sudowrap to be used in subshells
export -f sudowrap

Control iTunes over SSH

So I was looking for a good way to control iTunes running on my Mini mac at home. There's some payware options, like netTunes and webRemote, and some freeware options, like zTunes and iTRC. I kind of prefer using open source if I can get it, so I am giving the payware options a miss for now. Unfortunately none of the freeware options are cross-platform and secure at the same time. On top of that, most of the them are quite buggy. So while I wait for zTunes to become faster, less buggy and more secure, I chose the third option, which is Write Your Own :-) Thanks to the wonders of Applescript, iTunes is very accessible from other programs. You can basically get information about anything in your library and perform almost all the actions that you can perform from the program itself. So I wrote a remote control in bash, to be accessed over SSH. I present to you iTunesCLI 1.0. To use, save this script where you can find it again on the system that you want to use it from, for example in your home directory or in /usr/bin. Make it executable with chmod +x Then ssh to that system and run the script:

ssh -t mysystem ./iTunesCLI (when stored in your home directory)

ssh -t mysystem iTunesCLI (when stored in /usr/bin)

The -t option is needed to make keystrokes be recognized immediately. SSH tips:

• Use an SSH agent so you don't have to type your password every time. For OS X, try for example SSH Keychain
• The hostname for the remote machine is most likely machinename.local. For example, my Mac Mini is hooked up to the stereo and is called mini-me. I just run "ssh -t mini-me.local iTunesCLI".

I had to come up with some nifty tricks to make it fast and pretty. Look at the script file to see bash arrays, IFS swizzling, printf builtins, tput abuse, multiline commandlines embedded in backticks and a mangled model-view-controller concept, oh my! I sprinkled it with comments in the hopes of making it maintainable :-) Enjoy!