#!/bin/bash

# week7-demo-1

# Author:  Murray Saul
# Date:    Feb 13, 2021
#
# Purpose: Demonstration to user that you can run shell scripts that
#          will run operations in GRAPHICAL MODE since Live Knoppix
#          OS runs in a graphical desktop environment.
#
#          Student performing this OPTIONAL (but cool) tutorial can see
#          the practicality of installing graphical shell scripts which
#          may provide students a PRIMER for the importance of automating
#          tasks in the UNIX / Linux environment.


# Using "command substitution" (taught in week 12) at the end of this course
# to GRAPHICALLY store output from issuing commands. In this case, store the results from
# issuing the "zenity" command to prompt user graphically for a directory
# pathname selection. Command redirects stderr to /dev/null to "throw-out" warnings
# that normally occur from using the "zenity" command.

selection=$(zenity --title "Directory Selection Window" --list --radiolist --text "<b>Please Select a Directory</b>" --hide-header --column "Select" --column "Directory" FALSE "/home/$USER" FALSE "/bin" FALSE "/dev" FALSE "/etc" 2> /dev/null)

# Again, using "zenity" command to GRAPHICALLY display stdout from the "ls" command 
# for the selected directory pathname by using "command substitution"
# and expanding the "selection" variable that was set in previous command.
# Again, stderr from the command within "command substitution" is redirected
# (thrown-out) to /dev/null to avoid displaying warnings associated with
# running the "zenity" command.

zenity --title "Directory Contents Window" --info --text "<b>Contents of \"$selection\" Directory:</b>\n\n$(ls $selection)" 2> /dev/null

# Finally, graphically display that the program has ended and
# instructs the user to press OK to close the dialog box and
# proceed with the Knoppix tutorial.

zenity --title "Completed Script Window" --info --text " \
Well Done!\n\nYou have completed running this demonstration script.\nClick <b>OK</b> and proceed with this tutorial.\n" 2>/dev/null

# End of Bash Shell Script #