Easy setup for Ubuntu background image (installation using /bin) [recommended]

setbg.sh

#!/bin/bash
# @author     Mansour Yaacoubi
# @filename   setbg.sh
# @version    2.3
# @task       Sets background in Ubuntu and some other Linux versions
# @feature    When this script runs as superuser,
#             the command 'setbg' can be installed into /bin directory
# @timestamp  15:53 12.06.2017
# @usage      ./setbg.sh wallpaper.jpg
#             su $USER -c setbg.sh wallpaper.jpg
#             setbg wallpaper.jpg (after script was installed)

boldcmd="\033[1msetbg\033[0m"
                      
bin=/bin/setbg
TMP=/tmp
tmpscript=$TMP/$(basename $0)
# Check whether help option is chosen
if [ "$1" == "--help" ] || [ "$1" == "-h" ]; then
  echo "Usage: setbg [OPTION] [FILE]"
  if [ ! -f $bin ]; then echo "Example: sudo $0 -i"; fi;
  echo "Example: setbg wallpaper.jpg"
  echo "Sets background of current user. Expects wallpaper-image as first argument."
  if [ ! -f $bin ]; then echo "Install-option needs root-privileges."; fi;
  echo ""
  
  echo "Mandatory arguments to long options are mandatory for short options too."
  echo -e "\\t-h, --help\\t\\tprints this help text"
  if [ ! -f $bin ]; then echo -e "\\t-i, --install\\t\\tinstalls this script; needs to run as sudo"; fi;
  exit
# Check whether install option is chosen
elif [ "$1" == "--install" ] || [ "$1" == "-i" ]; then
	if [ -f $bin ]; then
		echo "Command has already been installed."
		exit
	fi
  if [ "$UID" -ne 0 ]; then
    echo -e "To install this script ($boldcmd), please run as superuser."
    echo -e "To install, run script like this:\\n"
    echo "sudo $0 $1"
    exit
  fi
  echo -e "Command $boldcmd will be installed..."
# Check whether argument is empty or file does not exists
elif [ -z "$1" ] || [ ! -f "$1" ] && [ "$1" != "install" ]; then
  echo "Please provide a valid image-file"
  exit
# Set background or warn to use normal user
else
  if [ "$UID" -eq 0 ]; then
    echo "Please don't run as root to set background."
    echo -e "Run script like this:\\n"
    if [ -f $bin ]; then echo "$(basename $0) $1"; exit; fi;             
    echo "$0 $1"
	exit
  else
    # GSettings cannot run with 'sudo' but with 'su $USER -c'
    gsettings set org.gnome.desktop.background picture-uri file://$(readlink -f $1)
	exit
  fi
fi

############################ SUPERUSER AREA ############################
# Everything below this text will be executed with elevated privileges #
########################################################################

cp $0 $TMP
chmod +rx $tmpscript
cp $tmpscript $bin
if [ $? -eq 0 ]; then
  echo -e "Command $boldcmd has been installed."
  rm $tmpscript
else
  echo -e "To install this script ($boldcmd), please run as superuser.\\nTo install, run script like this:\\n\\nsudo $0 $1"
fi