A monitor status switcher for the notebook, when we are using an external monitor as "primary" connected to VGA port

dualmon.sh

#!/bin/bash
#
# The MIT License (MIT)
#
# Copyright (c) 2016 Alexandre Magno ‒ [email protected]
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

PRIMARY=VGA1
SECUNDARY=LVDS1

LIST=$(xrandr --listmonitors | cut -d+ -f2 | cut -d" " -f1 | sed 1d)

function primary_is_OK_or_quit() {
    echo $LIST | grep "\*$PRIMARY" > /dev/null
    if [ $? -ne 0 ]; then
        echo "Primary monitor is wrong. Expected: $PRIMARY"
        echo
        xrandr --listmonitors
        exit 1
    fi
}

# TODO function secundary_is_OK_or_quit

function secundary_is_on() {
    echo $LIST | grep "$SECUNDARY" > /dev/null
    echo $?
}

function toggle_the_secundary() {
    if [ $(secundary_is_on) -eq 0 ]; then
        xrandr --output $SECUNDARY --off
    else
        xrandr --output $SECUNDARY --right-of $PRIMARY --auto
    fi
}

primary_is_OK_or_quit

# TODO call to secundary_is_OK_or_quit

toggle_the_secundary

exit 0


for i in $LIST; do
    echo
done