message_gui_user

#! /bin/bash

#----------------------------------------------------------------------
# Description: send a notification to a currently logged in user in X.org
# Author: Artem S. Tashkinov
# Created at: Thu Jan 16 22:57:14 2020
# It took me three hours to write and debug it though it looks simple
# Computer: zen
# System: Linux 5.4.8-az2 on x86_64
#
# Copyright (c) 2020 Artem S. Tashkinov  All rights reserved.
#
#----------------------------------------------------------------------

msg_icon=/path/to/icon_32x32.png

test -z "$3" && echo "Usage is `basename "$0"` timeout(seconds) title message" && exit 1
timeout=$1

# message type modern/classic
mstype=modern

if ! [[ "$1" =~ ^[0-9]+$ ]]; then
    echo "$1 is not an integer number."
    exit 1
fi


whos() # print users whose sessions start with ":"  i.e Xorg users
{
    who | awk '{if ($2~/^:/) print}'
}

message() {
    echo "Detected user:$1 DISPLAY=$2. Attempting to show a $mstype message ..."
    if [ "$mstype" = "classic" ]; then
        su "$1" -c "DISPLAY=$2 xmessage -center -timeout $timeout -title '$3' '$4'"
    else
        su "$1" -c "DISPLAY=$2 notify-send --expire-time="${timeout}000" --icon="$msg_icon" '$3' '$4'"
    fi
}

pid_lxdm=`pidof lxdm-session`
test -n "$pid_lxdm" && Xuser=`ps --no-headers -u --ppid "$pid_lxdm" | awk '{print $1}'`

if [ -n "$Xuser" ]; then
    # LXDM version
    echo "LXDM session detected ..."
    Xdisp=`ps --no-headers -u --ppid "$pid_lxdm" | awk '{print $2}'`
    Xdisp=`tr '\0' '\n' < /proc/$Xdisp/environ | awk -F = '/^DISPLAY=/{print $2}'`
    message "$Xuser" "$Xdisp" "$2 for ${timeout}sec" "$3"
elif [ -n "`whos`" ]; then
    # Universal version in case w does work (it doesn't for LXDM)
    echo "who is working :)"
    whos | while read Xuser Xdisp; do
        message "$Xuser" "$Xdisp" "$2 for ${timeout}sec" "$3"
    done
else
    echo "Attemptin to show a display login manager message ..."
    message "root" ":0" "$2 for ${timeout}sec" "$3"
fi