A shell script to act like a KVM switch using DDC controls

README

Step 1 - Install ddcctl and/or ddccontrol
Step 2 - figure out your input source values for your monitor(s)
Step 3 - map those commands to some hotkeys in your OS(es)
Step 4 - Probs get a cheap USB switch for keyboard and mouse sharing
Step 5 - Profit

cm

#!/bin/bash

# Author: github.com/cornercase
# Written: August 8, 2020
# License: WTFPL

# Dependecies
#   MacOS
#      ddcctl - for MacOS - https://github.com/kfix/ddcctl
#   Linux
#      ddccontrol - for linux - https://github.com/ddccontrol/ddccontrol



: '
My little scratchpad
# for Dell P2213 monitor
using ddcctl, input IDs are
 - VGA = 1
 - DVI = 3-14
 - DisplayPort = 15-17


Dell P2213 EDID Serial FJ44J3CHAY6S is the left monitor (ie main).  
 - Linux - /dev/i2c-1 = left monitor (VGA)
 - MacOS - 1 = left monitor (DVI)
Dell P2213 EDID Serial FJ44J26IAJ8S is the right monitor (ie secondary)  
 - Linux - /dev/i2c-5 = right monitor (DVI)
 - MacOS - 2 = right monitor (Displayport)

'

# are we in MacOS or Linux?
if command -v ddccontrol &> /dev/null
then
    echo "ddccontrol found, we're in linux"
    OS='linux'
    MONITORS=('/dev/i2c-1' '/dev/i2c-5')
fi

if command -v ddcctl &> /dev/null
then
    echo "ddcctl found, we're in macos"
    OS='mac'
    MONITORS=(1 2)
fi

# set mac mini inputs to DVI-D on monitor 1, displayport on monitor 2
if [ $1 = 'mm' ]
then
    SOURCES=(3 15)
fi

# set desktop inputs to VGA on monitor 1, DVI-D on monitor 2
if [ $1 = 'dt' ]
then
    SOURCES=(1 3)
fi

if [ ${#MONITORS[*]} -ne ${#SOURCES[*]} ]
then
    echo "Number of monitors (${#MONITORS[*]}) doesn't equal number of sources ${#SOURCES[*]}"
    exit
fi


for index in ${!MONITORS[*]}
do
    case $OS in
        'mac' )
            ddcctl -d ${MONITORS[$index]} -i ${SOURCES[$index]}
            ;;
        'linux' )
            sudo ddccontrol -r 0x60 -w $${SOURCES[$index]} dev:${MONITORS[$index]}
            ;;
    esac
done


#sudo ddccontrol -r 0x60 -w 15 dev:/dev/i2c-5    

LICENSE

DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
                   Version 2, December 2004
 
Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>

Everyone is permitted to copy and distribute verbatim or modified
copies of this license document, and changing it is allowed as long
as the name is changed.
 
           DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
  TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

 0. You just DO WHAT THE FUCK YOU WANT TO.