Toggle between laptop and external monitor

externalmonitor

#!/bin/bash
# Toggle between laptop and external monitor

# Required program(s)
req_progs=(bc)
for p in ${req_progs[@]}; do
  hash "$p" 2>&- || \
  { echo >&2 " Required program \"$p\" not installed."; exit 1; }
done

# Ports for Laptop and External monitor (AMD Catalyst drivers):
int_mon="LVDS"    # Aspire        1366x768
ext_mon="DFP1"    # Samsung SA350 1920x1080

# Ports for Laptop and External monitor (Open-source Radeon drivers):
#int_mon="eDP"     # Aspire        1366x768
#ext_mon="HDMI-0"  # Samsung SA350 1920x1080

# Discover if external monitor is connected
em_test=$(xrandr | grep $ext_mon | grep " connected")

# Enable external monitor if present and disable laptop monitor, else vice versa
if [ -n "$em_test" ]; then
  # External monitor definitions:
  # physical screen size from xrandr (xorg detection isn't right)
  em_ds_h=$(xrandr | grep $ext_mon | rev | cut -d " " -f 3 | rev | sed 's/mm//')
  em_ds_v=$(xrandr | grep $ext_mon | rev | cut -d " " -f 1 | rev | sed 's/mm//')
  em_ds="$em_ds_h"x"$em_ds_v"
  xrandr --output $int_mon --off --output $ext_mon --auto --fbmm $em_ds
else
  # physical screen size from xrandr (xorg detection isn't right)
  xrandr --output $ext_mon --off
  xrandr --output $int_mon --auto  # monitor must be on to get display size
  im_ds_h=$(xrandr | grep $int_mon | rev | cut -d " " -f 3 | rev | sed 's/mm//')
  im_ds_v=$(xrandr | grep $int_mon | rev | cut -d " " -f 1 | rev | sed 's/mm//')
  im_ds="$im_ds_h"x"$im_ds_v"
  xrandr --output $int_mon --auto --fbmm $im_ds
fi

# Text scaling: font scaling correction depending on DPI (adjusted here because
# Gnome considers every monitor 96 DPI for multi-monitors setups (makes
# multiple monitors have the same text sizes).  Detection assumes square pixels.
if [ -n "$em_test" ]; then
  # horizontal resolution (using preferred [xrandr --auto]); , to calculate DPI.
  em_res_h=$(xrandr | grep $em_ds_h | awk '{print $3}' | cut -d x -f 1)
  # dpi
  em_dpi=$(echo "scale=3;($em_res_h*25.4)/$em_ds_h" | bc)
  em_txt_scale=$(echo "scale=4;$em_dpi/96" | bc)
  #em_txt_scale=$(scale=3;echo "$em_txt_scale * 0.885" | bc)     # fonts too big
  #em_txt_scale=$(scale=3;echo "$em_txt_scale * 1" | bc)     # fonts too big
  gsettings set org.gnome.desktop.interface text-scaling-factor $em_txt_scale
else
  # horizontal resolution
  im_res_h=$(xrandr | grep $im_ds_h | awk '{print $3}' | cut -d x -f 1)
  # dpi
  im_dpi=$(echo "scale=3;($im_res_h*25.4)/$im_ds_h" | bc)
  im_txt_scale=$(echo "scale=4;$im_dpi/96" | bc)
  #im_txt_scale=$(scale=3;echo "$im_txt_scale * 0.885" | bc)     # fonts too big
  #im_txt_scale=$(scale=3;echo "$im_txt_scale * 1" | bc)     # fonts too big
  gsettings set org.gnome.desktop.interface text-scaling-factor $im_txt_scale
fi