switchmon/swm

#!/usr/bin/env bash
#
# Enable all connected montiors, disable all disconnected ones.
# Multiple monitors will be added to the right of previous ones.
#
# Author Thomas Ruoff <ThomasRuoff@gmail.com>

set -e

usage() {
    echo "swm - a helper to switch connected monitors";
    echo;
    echo "usage: swm [monitor]";
    echo;
    echo "If monitor is not passed it turns on all connected devices";
    echo "and lays them out next to each other in the order detected.";
    echo;
    echo "monitor: The string as reported by the script. If provided only";
    echo "this monitor will be turned on.";
}

echoerr() { echo "$@" 1>&2; }

getFirstWord() {
    awk '{print $1}'
}

linesToWords() {
    awk 'BEGIN{ORS=" "} {print}'
}

wordsToLines() {
    awk 'BEGIN{RS=" "} {print}'
}

without() {
    comm -3 <(echo "$1") <(echo "$2")
}


if [[ $1 == "-h" ]] || [[ $1 == "--help" ]] ; then
    usage
    exit
fi

TARGET=$1;
CONNECTED=$( xrandr | grep " connected" | sort | getFirstWord);
DISCONNECTED=$( xrandr | grep "disconnected" | sort | getFirstWord);

POSTCMD="herbstclient reload";

echo connected devices: $(echo $CONNECTED | wordsToLines);
echo disconnected devices: $(echo $DISCONNECTED | wordsToLines);

if [[ -n "$TARGET" ]] && [[ ! "$CONNECTED" =~ "$TARGET" ]] ; then
    echoerr "error: device $1 is not connected";
    exit 1;
fi

FORON=${@-$CONNECTED};

FOROFF="$DISCONNECTED $(without "$CONNECTED" "$FORON")";

# turn off all disconnected monitors
XRANDR_OFF_OPTIONS="";
for mon in $FOROFF; do
    XRANDR_OFF_OPTIONS+=" --output $mon --off";
done

# turn on all connected monitors
XRANDR_ON_OPTIONS="";
LAST="";
for mon in $FORON; do
    XRANDR_ON_OPTIONS+=" --output $mon --auto";
    if [ ! -z $LAST ]; then
        XRANDR_ON_OPTIONS+=" --right-of $LAST";
    fi
    LAST=$mon;
done

xrandr $XRANDR_ON_OPTIONS $XRANDR_OFF_OPTIONS &&\
    echo Activated monitors: ${FORON} &&\
    $POSTCMD;