Desktop Notifications 4 Sys. Scripts (cron, init.d, upstart)

#!/bin/bash
me=$0;
usage(){
    echo
    echo 'Overview:'
    echo '- Must be run as super user (i.e. root).'
    echo '- Delegates to the notify-send command. See notify-send man page for additional options.'
    echo '- <username> is the username of the user who will receive the desktop notification.'
    echo
    echo "Usage:"
    echo "- \"sudo notify-send-user -U <username> [notify-send options]\" - General pattern send <username> a desktop notification. See notify-send man page."
    echo "- \"sudo notify-send-user -U johndoe -i info \"Subject\" \"Message loreum ipsum dolor\"\" - Mock usage for hypothetical user named johndoe."
    echo "- \"notify-send-user -h\" - display usage information (what is displayed currently)"
    echo
}


#Process command line to retrieve the user who will receive the notification
while getopts ":hU:" option; do
    case "$option" in
        h) usage
            exit 0;;
        U) user=$OPTARG;;
    :) echo "  Error: -$OPTARG requires an argument."
        usage
            exit 0;;
        ?) ;; #unknown option - path thru to notify-send
        *) ;; #unimplimented option - path thru to notify-send
    esac
done

#check that a username was provided
if [ -z "$user" ]
then
    echo "  Error: a valid username must be specified"
    usage
    exit 0
fi

export DISPLAY=:0.0
#build the wrapped notify-send by passing all command line arguments except the -U options which is specific to this script

command="sudo -u $user notify-send";
for input in "${@:1}"; do
    if [[ "$input" = "$user" ||  "$input" = "-U" ]]
    then
        command+='' #skip
    else
    command+=$IFS #input field separator

        #input contains spaces so add single quotes (expansion has already occured) and escape single quotes

    if [[ "$input" =~ " " ]]; then
        escaped=${input/[']/\'/g}
        command+="'"
        command+="${escaped}"
        command+="'"
    else
        command+="$input"
    fi;
    fi;
done;

#run the rebuilt notify-send command
eval $command