rerandr3

#!/bin/bash
# rerandr3 - Bash multimonitor handler daemon
# by Vladimir Kudrya
# https://github.com/Vladimir-csp/
#
# This script is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version. See <http://www.gnu.org/licenses/>.

# for help see show_help function or run rerandr3 help

# hook trigger boundary in pixel quantity (width*height)
# 1366 * 768 = 1049088
PIXEL_TRIGGER=1100000

# which strategy to use when autostacking
# (xrandr relative position options: --right-of, --left-of, --above, --below)
STACK_STRATEGY="--right-of"

SOCKET="/tmp/rerandr3.fifo"
DAEMON_LOG="$HOME/.rerandr3.log"
UDEV_RULE_FILE="/etc/udev/rules.d/95-rerandr3-monitor-trigger.rules"
UDEV_RULE="KERNEL==\"card0\", SUBSYSTEM==\"drm\",  RUN+=\"$(readlink -f "$0") trigger-restore\""

# Name of X process, needed for some checks
XORG_PROCESS=Xorg

# check for needed tools
BINFAIL=0
for BINARY in xrandr xxd sed tr xdpyinfo
do
	which $BINARY >/dev/null || { printf "%s\n" "$BINARY binary not found!" >&2 ; BINFAIL=1 ;}
done
[ "$BINFAIL" = "1" ] && exit 1 || true
unset BINFAIL

show_help(){
	cat << "EOF"
syntax:

	rerandr command

where command is one of:

	save - save current uniqe monitor setup based on output names and
	monitor models from EDID data.

	restore - if current monitor setup is known, apply stored config.
	If setup is unknown, try to disable everything disconnected and
	enable and stack everything connected.

	show - dump setup ID and xrandr arguments of current state.

	daemon - launch user session daemon for automatic triggering.

	trigger-save - tell daemon to do save.

	trigger-restore - tell daemon to restore configuration.

	hooks - just apply screen hooks

	insert-udev - insert udev rule for auto triggering.

to use rerandr3 in 'full auto', create udev rule:

	KERNEL=="card0", SUBSYSTEM=="drm", RUN+="/full/path/to/rerandr3 trigger-restore"

EOF
}

##############################################
#### window hooks
##############################################

hooks() {
	## do things on every switch
	printf "%s\n" "Applying general hooks."

	## get DPI
	#DPI="$(xdpyinfo | grep 'resolution:' | grep -o '[0-9]\+x[0-9]\+' | head -n 1 | cut -d 'x' -f 1)"
	## sync dpi to xrdb
	#printf "%s\n" "Xft.dpi: $DPI" | xrdb -merge
	## sync dpi to fontconfig
	#mkdir -p "${XDG_CONFIG_HOME:-$HOME/.config}/fontconfig/conf.d"
	#cat > "${XDG_CONFIG_HOME:-$HOME/.config}/fontconfig/conf.d/90-rerandr3-dpi.conf" << EOF
#<?xml version="1.0"?>
#<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
#<!-- Generated by rerandr3, do not edit. -->
#<fontconfig>
#  <match target="pattern">
#    <edit name="dpi" mode="assign"><double>$DPI</double></edit>
#  </match>
#</fontconfig>
#EOF

	#which nitrogen > /dev/null && nitrogen --restore
	#{ pgrep -u "$USER" conky > /dev/null 2> /dev/null && sleep 1 && killall -USR1 conky ; } &
}

smallhooks() {
	# do things if screen area is less than $PIXEL_TRIGGER
	printf "%s\n" "Applying small screen hooks."
	#wmctrl -xr Firefox		-b "add,maximized_horz,maximized_vert"
	#wmctrl -xr Thunderbird		-b "add,maximized_horz,maximized_vert"
	#wmctrl -xr Spacefm		-b "add,maximized_horz,maximized_vert"
}

largehooks() {
	# do things if screen area is greater than $PIXEL_TRIGGER
	printf "%s\n" "Applying large screen hooks."
	#wmctrl -xr Firefox	-b "remove,maximized_vert,maximized_horz"
	#wmctrl -xr Thunderbird	-b "remove,maximized_vert,maximized_horz"
	#wmctrl -xr Spacefm	-b "remove,maximized_vert,maximized_horz"
	#wmctrl -xr Firefox	-e "0,-1,-1,1280,$HEIGHT"
	#wmctrl -xr Thunderbird	-e "0,-1,-1,1280,$HEIGHT"
	#wmctrl -xr Spacefm	-e "0,-1,-1,1280,$HEIGHT"
}

applyhooks() {
	# skip if run by root (DM, etc)
	[ "$(id -ru)" = "0" ] && return 0

	# calculate dimensions and apply hooks
	DIMENSIONS="$(xdpyinfo | grep dimensions | grep -o '[0-9]\+x[0-9]\+' | head -n 1)"
	WIDTH="$(printf "%s\n" "$DIMENSIONS" | cut -d x -f 1)"
	HEIGHT="$(printf "%s\n" "$DIMENSIONS" | cut -d x -f 2)"
	PIXELS="$(( $WIDTH * $HEIGHT ))"
	printf "%s\n" "Pixel quantity: $PIXELS"
	if [ "$PIXELS" -gt "$PIXEL_TRIGGER" ] ; then
		hooks
		largehooks
	else
		hooks
		smallhooks
	fi
	# hooks must not fail
	true
}

prepare_confdir(){
	if [ -n "$XDG_CONFIG_HOME" ]
	then
		CONF_DIR="$XDG_CONFIG_HOME/rerandr3"
	else
		CONF_DIR="$HOME/.config/rerandr3"
	fi
	mkdir -p "$CONF_DIR"

	[ -d "$CONF_DIR" -a -w "$CONF_DIR" ] || { printf "%s\n" "Could not access config directory \"$CONF_DIR\"!" >&2 ; exit 1 ;}
}

prepare_pipe(){
	[ ! -p "$SOCKET" ] && mkfifo -m 666 "$SOCKET"
	[ "$(stat -c %a "$SOCKET")" != "666" ] && chmod 666 "$SOCKET"
	[ ! -p "$SOCKET" -a "$(stat -c %a "$SOCKET")" != "666" ] && { printf "%s\n" "Could not prepare named pipe \"$SOCKET\"!" >&2 ; exit 1 ;}
}

get_data(){
	# parsing verbose xrandr output
	OUTPUT_NUM=-1
	unset OUTPUT STATUS ROLE POSITION POSITION_X POSITION_Y CRTC MODEL SERIAL MODE_CURRENT MODE_PREFERRED EDID EDID_CATCH RANDR ROTATION REFLECTION GAMMA BRIGHTNESS TRANSFORM SCREEN_NUM DIMENSIONS
	OIFS=$IFS
	printf "%s\n" "Gathering data..."
	IFS=
	while read LINE ; do
		# get output name and status
		# triggered by and connection status keyword and lack of indent.
		if printf "%s" "$LINE" | grep -q '^Screen[[:space:]]\+[0-9]\+:'
		then
			# found new screen
			SCREEN_NUM="$(printf "%s" "$LINE" | grep -o '^Screen[[:space:]]\+[0-9]\+:' | grep -o '[0-9]\+')"
			# we really support only one screen
			[ "$SCREEN_NUM" -gt "0" ] && break
			DIMENSIONS="$(printf "%s" "$LINE" | grep -o 'current[[:space:]]\+[0-9]\+[[:space:]]*x[[:space:]]*[0-9]\+' | grep -o '[0-9]\+[[:space:]]*x[[:space:]]*[0-9]\+' | tr -d '[[:space:]]')"
			# done with this line
			continue
		fi
		if printf "%s" "$LINE" | grep -q '^[[:alnum:]_-]\+[[:space:]]\+\(connected\|disconnected\)'
		then
			# found new output
			OUTPUT_NUM=$(( $OUTPUT_NUM + 1 ))
			# get name, first non-whitespace block
			OUTPUT[$OUTPUT_NUM]="$(printf "%s" "$LINE" | grep -o '^[^[:space:]]\+')"
			# get status by keyword
			STATUS[$OUTPUT_NUM]="$(printf "%s" "$LINE" | grep -ow 'connected\|disconnected')"
			# check if primary
			ROLE[$OUTPUT_NUM]="$(printf "%s" "$LINE" | grep -ow 'primary')"
			# get mode (XxY string)
			MODE_CURRENT[$OUTPUT_NUM]="$(printf "%s" "$LINE" | grep -o '[0-9]\+x[0-9]\+[+-][0-9]\+[+-][0-9]\+' | grep -o '[0-9]\+x[0-9]\+')"
			# everything else is irrelevant if output is disconnected
			if [ "${STATUS[$OUTPUT_NUM]}" = "connected" ]
			then
				# get position (+X+Y string and each component)
				POSITION[$OUTPUT_NUM]="$(printf "%s" "$LINE" | grep -o '[0-9]\+x[0-9]\+[+-][0-9]\+[+-][0-9]\+' | grep -o '[+-][0-9]\+[+-][0-9]\+')"
				POSITION_X[$OUTPUT_NUM]="$(printf "%s" "${POSITION[$OUTPUT_NUM]}" | grep -o '[+-][0-9]\+' | head -n 1)"
				POSITION_Y[$OUTPUT_NUM]="$(printf "%s" "${POSITION[$OUTPUT_NUM]}" | grep -o '[+-][0-9]\+' | tail -n 1)"
				# active reflect and rotation settings are between ") ... ("
				RANDR[$OUTPUT_NUM]="${LINE#*)}"
				RANDR[$OUTPUT_NUM]="${RANDR[$OUTPUT_NUM]%%(*}"
				# get rotation by keyword
				ROTATION[$OUTPUT_NUM]="$(printf "%s" "${RANDR[$OUTPUT_NUM]}" | grep -o 'normal\|right\|inverted|\left')"
				# words 'x' and 'y' represent reflection, may vary in case
				# conditionally compose proper value for --reflect
				printf "%s" "${RANDR[$OUTPUT_NUM]}" | grep -qiw 'x' && REFLECTION[$OUTPUT_NUM]="x"
				printf "%s" "${RANDR[$OUTPUT_NUM]}" | grep -qiw 'y' && REFLECTION[$OUTPUT_NUM]="${REFLECTION[$OUTPUT_NUM]}y"
				[ -z "${REFLECTION[$OUTPUT_NUM]}" ] && REFLECTION[$OUTPUT_NUM]="normal"
			fi
			# done with this line
			continue
		fi

		# get CRTC
		# using crtc in saved configs works around xrandr position restore bug... theoretically
		# update: it does not, but messes things up when trying to shuffle CRTCs around enabled outputs
		if printf "%s" "$LINE" | grep -q '^[[:space:]]\+CRTC:'
		then
			CRTC[$OUTPUT_NUM]="$(printf "%s" "$LINE" | grep -o '[0-9]\+')"
			# done with this line
			continue
		fi

		# trigger EDID catching
		if printf "%s" "$LINE" | grep -q '^[[:space:]]\+EDID:'
		then
			EDID_CATCH=1
			# done with this line, data comes next
			continue
		fi

		# catch and combine EDID string
		if [ "$EDID_CATCH" = "1" ]
		then
			# capture while line contains only hexadecimal string
			if printf "%s" "$LINE" | grep -q '^[[:space:]]\+[[:xdigit:]]\+$'
			then
				EDID[$OUTPUT_NUM]="${EDID[$OUTPUT_NUM]}$(printf "%s" "$LINE" | grep -o '[[:xdigit:]]\+')"
				# get next line
				continue
			else
				# edid string is over
				unset EDID_CATCH
				# extract data. Mad skillz in voodoo magic are used here.
				EDID[$OUTPUT_NUM]=$(printf "%s" "${EDID[$OUTPUT_NUM]}" | fold -w2 | paste -sd\ )
				MODEL[$OUTPUT_NUM]="${EDID[$OUTPUT_NUM]##*fc}"
				MODEL[$OUTPUT_NUM]="${MODEL[$OUTPUT_NUM]%%0a*}"
				MODEL[$OUTPUT_NUM]="$(printf "%s" "${MODEL[$OUTPUT_NUM]}" | xxd -r -p | tr -cd '\11\12\15\40-\176' | sed 's/[^a-zA-Z0-9_[:space:]-]//g;s/^[[:space:]]\+\|[[:space:]]\+$//g;s/[[:space:]]\+/_/g')"
				SERIAL[$OUTPUT_NUM]="${EDID[$OUTPUT_NUM]##*ff}"
				SERIAL[$OUTPUT_NUM]="${SERIAL[$OUTPUT_NUM]%%0a*}"
				SERIAL[$OUTPUT_NUM]="$(printf "%s" "${SERIAL[$OUTPUT_NUM]}" | xxd -r -p | tr -cd '\11\12\15\40-\176' | sed 's/[^a-zA-Z0-9_[:space:]-]//g;s/^[[:space:]]\+\|[[:space:]]\+$//g;s/[[:space:]]\+/_/g')"

				# do not skip line here, it may contain other data
			fi
		fi

		# trigger transformation catching
		if printf "%s" "$LINE" | grep -q '^[[:space:]]\+Transform:'
		then
			TRANSFORM_CATCH=1
			# remove header
			LINE="${LINE#*:}"
			# do not skip, data already begins on the same line
		fi

		# catch and combine transformation data
		if [ "$TRANSFORM_CATCH" = "1" ]
		then
			# capture while line contains only digits and spaces
			if printf "%s" "$LINE" | grep -q '^[[:space:]]\+[0-9\.[:space:]-]\+$'
			then
				# we need all the figures separated by commas in one line
				[ -n "${TRANSFORM[$OUTPUT_NUM]}" ] && FORMATTER=',' || unset FORMATTER
				TRANSFORM[$OUTPUT_NUM]="${TRANSFORM[$OUTPUT_NUM]}${FORMATTER}$(printf "%s" "$LINE" | sed 's/[^0-9\.[:space:]-]//g;s/^[[:space:]]\+\|[[:space:]]\+$//g;s/[[:space:]]\+/,/g')"
				# get next line
				continue
			else
				# transform data is over
				unset TRANSFORM_CATCH
				# do not skip cycle here, we are not on transform line any more
			fi
		fi

		# get gamma and brightness
		printf "%s" "$LINE" | grep -q '^[[:space:]]\+Gamma:' && GAMMA[$OUTPUT_NUM]="$(printf "%s" "$LINE" | sed 's/^[[:space:]]\+Gamma:[[:space:]]*//')"
		printf "%s" "$LINE" | grep -q '^[[:space:]]\+Brightness:' && BRIGHTNESS[$OUTPUT_NUM]="$(printf "%s" "$LINE" | sed 's/^[[:space:]]\+Brightness:[[:space:]]*//')"

		# get preferred mode
		if printf "%s" "$LINE" | grep -q '^[[:space:]]\+[0-9]\+x[0-9]\+'
		then
			# get by +preferred keyword
			if printf "%s" "$LINE" | grep -q '\+preferred'
			then
				MODE_PREFERRED[$OUTPUT_NUM]="$(printf "%s" "$LINE" | grep -o '[0-9]\+x[0-9]\+')"
			fi
			continue
		fi
	done < <(xrandr --verbose)
	IFS=$OIFS

	# get DPI value
	DPI="$(xdpyinfo | grep 'resolution:' | grep -o '[0-9]\+x[0-9]\+' | head -n 1 | cut -d 'x' -f 1)"
}

dump_args(){
	# return current screen config formatted in xrandr cli arguments
	for OUTPUT_NUM in ${!OUTPUT[@]}
	do
		printf "%s" "--output ${OUTPUT[$OUTPUT_NUM]} "
		if [ -z "${MODE_CURRENT[$OUTPUT_NUM]}" ]
		then
			printf "%s" "--off "
		else
			printf "%s" "--mode ${MODE_CURRENT[$OUTPUT_NUM]} --pos ${POSITION_X[$OUTPUT_NUM]}x${POSITION_Y[$OUTPUT_NUM]} "
			[ -n "${ROTATION[$OUTPUT_NUM]}" ] && printf "%s" "--rotate ${ROTATION[$OUTPUT_NUM]} "
			[ -n "${REFLECTION[$OUTPUT_NUM]}" ] && printf "%s" "--reflect ${REFLECTION[$OUTPUT_NUM]} "
			# disable CRTC saving, serves no real purpose, but breaks things sometimes.
			# [ -n "${CRTC[$OUTPUT_NUM]}" ] && printf "%s" "--crtc ${CRTC[$OUTPUT_NUM]} "
			[ -n "${GAMMA[$OUTPUT_NUM]}" ] && printf "%s" "--gamma ${GAMMA[$OUTPUT_NUM]} "
			[ -n "${BRIGHTNESS[$OUTPUT_NUM]}" ] && printf "%s" "--brightness ${BRIGHTNESS[$OUTPUT_NUM]} "
			[ -n "${TRANSFORM[$OUTPUT_NUM]}" ] && printf "%s" "--transform ${TRANSFORM[$OUTPUT_NUM]} "
			[ "${ROLE[$OUTPUT_NUM]}" = "primary" ] && printf "%s" "--primary "
		fi
	done
	[ -n "$DPI" ] && printf "%s" "--dpi $DPI "
}

dump_id(){
	# generate and return setup ID based on output names, display models and serial numbers
	FORMATTER=
	for OUTPUT_NUM in ${!OUTPUT[@]}
	do
		if [ "${STATUS[$OUTPUT_NUM]}" = "connected" ]
		then
			[ -n "$FORMATTER" ] && printf "%s" "-"
			FORMATTER=1
			printf "%s" "${OUTPUT[$OUTPUT_NUM]}"
			[ -n "${MODEL[$OUTPUT_NUM]}" ] && printf "%s" "-${MODEL[$OUTPUT_NUM]}"
			# do not output serial number, makes setups more portable
			#[ -n "${SERIAL[$OUTPUT_NUM]}" ] && printf "%s" "-${SERIAL[$OUTPUT_NUM]}"
		fi
	done
}

save_setup(){
	SETUP_ID=$(dump_id)
	SETUP_ARGS=$(dump_args)
	printf "%s\n" "Saving configuration for setup \"${SETUP_ID}\"..."
	printf "%s\n" "$SETUP_ARGS" > "$CONF_DIR/${SETUP_ID}.rerandr"
}

show_setup(){
	SETUP_ID=$(dump_id)
	SETUP_ARGS=$(dump_args)
	printf "%s\n" "${SETUP_ID}"
	printf "%s\n" "$SETUP_ARGS"
}

apply_saved(){
	# read from config file, strip everything but injection-safe characters
	SAVED_SETUP_ARGS="$(cat "$CONF_DIR/${SETUP_ID}.rerandr" | sed 's/[^[:alnum:][:space:]\.,:_+-]//g')"
	if [ "$SETUP_ARGS" = "$SAVED_SETUP_ARGS" ]
	then
		printf "%s\n" "Nothing to do."
	else
		# first disable everything unneeded, this works around xrandr CRTC allocation bug
		# preserve framebuffer size to preserve window positions
		unset DISABLE_ARGS
		for OUTPUT_NUM in ${!OUTPUT[@]}
		do
			if [ -n "${MODE_CURRENT[$OUTPUT_NUM]}" ] && printf "%s" "$SAVED_SETUP_ARGS" | grep -q "\--output ${OUTPUT[$OUTPUT_NUM]} --off"
			then
				printf "%s\n" "Disabling unneeded output ${OUTPUT[$OUTPUT_NUM]}"
				DISABLE_ARGS="$DISABLE_ARGS --output ${OUTPUT[$OUTPUT_NUM]} --off"
			fi
		done
		[ -n "$DISABLE_ARGS" ] && xrandr --fb "$DIMENSIONS" $DISABLE_ARGS

		# apply saved config
		xrandr $SAVED_SETUP_ARGS
		if [ "$?" = "0" ]
		then
			# if applied successfully, go to hooks.
			applyhooks
		else
			# if something wend wrong, go through auto routine
			printf "%s\n" "Failed to apply saved configuration, trying auto..."
			apply_auto
		fi
	fi
}

apply_auto(){
	# autostacking
	# first disable disconnected outputs preserving framebuffer size
	# mark active and primary outputs in the process
	unset PRIMARY_NUM DISABLE_ARGS ACTIVE_NUMS ENABLE_NUMS LAST_ENABLED
	for OUTPUT_NUM in ${!OUTPUT[@]}
	do
		if [ "${STATUS[$OUTPUT_NUM]}" = "disconnected" -a -n "${MODE_CURRENT[$OUTPUT_NUM]}" ]
		then
			printf "%s\n" "Disabling disconnected output \"${OUTPUT[$OUTPUT_NUM]}\"..."
			DISABLE_ARGS="$DISABLE_ARGS --output ${OUTPUT[$OUTPUT_NUM]} --off"
			# clear mode for output to be disabled
			MODE_CURRENT[$OUTPUT_NUM]=
		elif [ "${STATUS[$OUTPUT_NUM]}" = "connected" -a -n "${MODE_CURRENT[$OUTPUT_NUM]}" -a "${ROLE[$OUTPUT_NUM]}" = "primary" ]
		then
			printf "%s\n" "found connected and active primary output ${OUTPUT[$OUTPUT_NUM]}"
			PRIMARY_NUM=$OUTPUT_NUM
			# collect active outputs
			ACTIVE_NUMS=( "${ACTIVE_NUMS[@]}" "$OUTPUT_NUM" )
		elif [ "${STATUS[$OUTPUT_NUM]}" = "connected" -a -n "${MODE_CURRENT[$OUTPUT_NUM]}" ]
		then
			# collect active outputs
			ACTIVE_NUMS=( "${ACTIVE_NUMS[@]}" "$OUTPUT_NUM" )
		elif [ "${STATUS[$OUTPUT_NUM]}" = "connected" -a -z "${MODE_CURRENT[$OUTPUT_NUM]}" ]
		then
			# collect inactive outputs to be enabled
			ENABLE_NUMS=( "${ENABLE_NUMS[@]}" "$OUTPUT_NUM" )
		fi
	done
	# apply disabing outputs
	[ -n "$DISABLE_ARGS" ] && xrandr --fb "$DIMENSIONS" $DISABLE_ARGS

	# if there is no active primary, make one from first active or whatever
	if [ -z "$PRIMARY_NUM" -a -n "${ACTIVE_NUMS[*]}" ]
	then
		printf "%s\n" "Making output ${OUTPUT[${ACTIVE_NUMS[0]}]} primary"
		xrandr --fb "$DIMENSIONS" --output "${OUTPUT[${ACTIVE_NUMS[0]}]}" --auto --primary
		PRIMARY_NUM="${ACTIVE_NUMS[0]}"
	elif [ -z "$PRIMARY_NUM" -a -z "${ACTIVE_NUMS[*]}" ]
	then
		printf "%s\n" "Enabling output ${OUTPUT[${ENABLE_NUMS[0]}]} as primary"
		xrandr --fb "$DIMENSIONS" --output ${OUTPUT[${ENABLE_NUMS[0]}]} --auto --primary
		ACTIVE_NUMS=( "${ENABLE_NUMS[0]}" "${ACTIVE_NUMS[@]}" )
		ENABLE_NUMS[0]=
	fi

	# start enabling and stacking outputs
	# enable sequential, single command will fail when we run out of CRTCs.
	LAST_NUM="$PRIMARY_NUM"
	for OUTPUT_NUM in ${ACTIVE_NUMS[@]} ${ENABLE_NUMS[@]}
	do
		if [ "$OUTPUT_NUM" != "$PRIMARY_NUM" ]
		then
			printf "%s\n" "Putting ouptut ${OUTPUT[$OUTPUT_NUM]} next to ${OUTPUT[$LAST_NUM]}"
			xrandr --output "${OUTPUT[$OUTPUT_NUM]}" --auto "$STACK_STRATEGY" "${OUTPUT[$LAST_NUM]}"
			LAST_NUM="$OUTPUT_NUM"
		fi
	done
	# in case framebuffer is still not updated to current config
	xrandr --auto

	applyhooks
}


apply_setup(){
	# get data
	SETUP_ID=$(dump_id)
	SETUP_ARGS=$(dump_args)

	# decide if restore saved or go with auto
	if [ -r "$CONF_DIR/${SETUP_ID}.rerandr" ]
	then
		printf "%s\n" "Applying configuration for setup \"${SETUP_ID}\"..."
		apply_saved
	else
		printf "%s\n" "No configuration found for setup \"${SETUP_ID}\"."
		apply_auto
	fi
}

getsessionpid(){
	# got this from fbpanel xlogout script, refined.
	# find PID of session manager process to exit when it no longer exists

	# get display number
	DPY=${DISPLAY#*\:}
	DPY=${DPY%%\.*}

	# get X pid
	XPID=$(cat "/tmp/.X${DPY}-lock" | grep -o '[0-9]\+')

	# get pid of xdm (or gdm, kdm, simple xinitrc, etc). usually it's parent of X
	XDMPID=$(ps -o ppid --no-headers --pid=$XPID)

	# recursivly find child of xdm that was started in home dir -
	# it's user's session start up script
		pid_scan(){
			unset XDMCHILDREN
			while [ $# != 0 ]; do
				XDMCHILDREN="$XDMCHILDREN $(ps --no-headers -o pid --ppid=$1)"
				shift
			done
			for pid in $XDMCHILDREN; do
				if cwd=$(ls -al /proc/$pid/cwd 2>/dev/null); then
					cwd=`sed 's/.*-> //' <<< $cwd`
					[ "$cwd" = "$HOME" ] && printf "%s\n" "$pid" && return
				fi
			done
			pids=$XDMCHILDREN
			[ -n "$pids" ] && pid_scan $XDMCHILDREN;

		}

	SESSIONPID=`pid_scan $XDMPID`

	[ -z "$SESSIONPID" ] && printf "%s\n" "No session parent found" >&2 && false
	[ -n "$SESSIONPID" ] && printf "%s" "$SESSIONPID"
}

check_udev(){
	[ ! "$(cat "$UDEV_RULE_FILE" 2>/dev/null)" = "$UDEV_RULE" ] && printf "%b" "Info:\trerandr3 udev rule \"$UDEV_RULE_FILE\" is missing or invalid.\n\tAutomatic triggering is not possible.\n\tRun \"$(basename "$0") insert-udev\" to insert rule.\n"
}

insert_udev(){
	if [ "$(id -ru)" = "0" ]
	then
		printf "%s\n" "$UDEV_RULE" > "$UDEV_RULE_FILE"
		udevadm control --reload
	else
		printf "%s\n" "You are not root. Can not insert udev rule" >&2
		exit 1
	fi
}

if [ "$1" = "help" -o "$1" = "--help" -o "$1" = "-h" ]
then
	show_help
elif [ "$1" = "save" ]
then
	prepare_confdir
	get_data
	save_setup
elif [ "$1" = "restore" ]
then
	prepare_confdir
	get_data
	apply_setup
elif [ "$1" = "show" ]
then
	prepare_confdir
	get_data
	show_setup
elif [ "$1" = "trigger-save" ]
then
	[ -p "$SOCKET" -a "$(stat -c %a "$SOCKET")" = "666" ] && printf "%s\n" "save" > "$SOCKET"
	true
elif [ "$1" = "trigger-restore" ]
then
	# if there is no Xorg running, exit (workaround for messing with boot via udev rule)
	ps -C "$XORG_PROCESS" >/dev/null 2>/dev/null || exit 0
	[ -p "$SOCKET" -a "$(stat -c %a "$SOCKET")" = "666" ] && printf "%s\n" "restore" > "$SOCKET"
	true
elif [ "$1" = "daemon" ]
then
	prepare_pipe 2>&1 | tee -a "$DAEMON_LOG"
	check_udev | tee -a "$DAEMON_LOG"

	# clean pipes
	cat /dev/null > "$SOCKET" &
	cat "$SOCKET" | head -c 128 > /dev/null

	"$0" restore 2>&1 | tee -a "$DAEMON_LOG"

	# session tracking
	getsessionpid
	MAINPID="$$"
	printf "%b"  "Started daemon. PID: $MAINPID\nTracking session leader: PID $SESSIONPID\n" | tee -a "$DAEMON_LOG"
	while true
	do
		kill -0 $SESSIONPID 2> /dev/null || { printf "%s\n" "exit" > "$SOCKET" ; exit 0 ; }
		kill -0 $MAINPID 2> /dev/null || exit 0
		sleep 3s
	done &

	applyhooks

	while true
	do
		printf "%s\n" "Waiting for socket trigger..."
		ACTION="$(cat "$SOCKET" | head -c 8 | sed 's/[^[:alpha:]_-]//g')"
		if [ "$ACTION" = "save" ]
		then
			"$0" save
			ACTION=
		elif [ "$ACTION" = "restore" ]
		then
			"$0" restore
			ACTION=
		elif [ "$ACTION" = "exit" ]
		then
			printf "%s\n" "Exiting..."
			exit 0
		else
			printf "%s\n" "Unknown action \"$ACTION\"."
			ACTION=
			sleep 5s
		fi
	done 2>&1 | tee -a "$DAEMON_LOG"
elif [  "$1" = "hooks" ]
then
	applyhooks
elif [ "$1" = "insert-udev" ]
then
	printf "%s\n" "Will now insert udev rule:
	$UDEV_RULE
in file:
	$UDEV_RULE_FILE
Root access required.
Press any key to continue, or Ctrl+c to cancel"
	read -sn1
	sudo "$0" root-insert-udev
elif [ "$1" = "root-insert-udev" ]
then
	insert_udev
else
	show_help
	exit 1
fi