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Tags: gnome   multiple-monitors   nvidia-geforce  
Link: 🔍 See Original Answer on Ask Ubuntu 🔗

URL: https://askubuntu.com/q/1075809
Title: How to auto execute command when starting second monitor?
ID: /2018/09/16/How-to-auto-execute-command-when-starting-second-monitor_
Created: September 16, 2018
Upload: November 24, 2022    Layout:  post
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This is a work-in-progress script I’m developing for a package to control monitor brightness and gamma based on sunrise/sunset times.

When closing the lid of the laptop, xrandr resets all external monitors to full brightness. The script below detects xrandr changes to /sys/class/drm/?/status file using inotify which is a more efficient polling method than sleeping every second.

The script below contains credits to original authors and portions are commented out that may be deleted in the future or changed.

Use ll /sys/class/drm/*/status to discover your monitor card name(s). Then replace MONITOR= below with the appropriate name.

Bash script

#!/bin/bash

# NAME: monitory-eyesome.sh
# PATH: /usr/lib/bin
# DESC: Instantly adjust display brightness when xrandr reconfigures monitors
#       and resets them to full brightness.

# CALL: /etc/cron.d calls this script during boot.
#       Called from command line for testing/debugging.

# DATE: Sepetmber ??, 2018.

# PARM: No parameters yet, but $1 will be /sys/class/drm/<MONITOR>/status
#       in the future. ie $1 = <MONITOR>

# source eyesome-src.sh # Common code for eyesome___.sh bash scripts

# Must have the inotify-tools package.
command -v inotifywait >/dev/null 2>&1 || { echo >&2 \
        "inotify-tools package required but it is not installed.  Aborting."; \
        exit 2; }

# Copied from: https://bbs.archlinux.org/viewtopic.php?id=171655
#inspired of: 
#   http://unix.stackexchange.com/questions/4489/a-tool-for-automatically-applying-randr-configuration-when-external-display-is-p
#   http://ozlabs.org/~jk/docs/mergefb/
#   http://superuser.com/questions/181517/how-to-execute-a-command-whenever-a-file-changes/181543#181543

export MONITOR="/sys/class/drm/card1-DP-1/status"
echo "$0: $(date) Monitoring: $MONITOR" > /tmp/monitor-eyesome.sh
while inotifywait -e modify,create,delete,open,close,close_write,access \
        "$MONITOR";

dmode="$(cat "$MONITOR")"

do
    echo "$0: $(date) $dmode" >> /tmp/monitor-eyesome.sh
#    if [ "${dmode}" = disconnected ]; then
#         /usr/bin/xrandr --auto
#         echo "${dmode}"
#    elif [ "${dmode}" = connected ];then
#         /usr/bin/xrandr --output VGA1 --auto --right-of LVDS1
#         echo "${dmode}"
#    else /usr/bin/xrandr --auto
#         echo "${dmode}"
#    fi
done

Sample output when closing laptop lid

$ sudo ./monitor-eyesome.sh
Setting up watches.
Watches established.
/sys/class/drm/card1-DP-1/status OPEN 
Setting up watches.
Watches established.
/sys/class/drm/card1-DP-1/status OPEN 
Setting up watches.
Watches established.
/sys/class/drm/card1-DP-1/status OPEN 
Setting up watches.
Watches established.

Sample output of log file

$ cat /tmp/mon*
./monitor-eyesome.sh: Sun Sep 16 11:16:51 MDT 2018 Monitoring: /sys/class/drm/card1-DP-1/status
./monitor-eyesome.sh: Sun Sep 16 11:16:55 MDT 2018 connected
./monitor-eyesome.sh: Sun Sep 16 11:16:56 MDT 2018 connected
./monitor-eyesome.sh: Sun Sep 16 11:16:56 MDT 2018 connected

Summary

This script was created a few minutes ago (Sept 16 2018 @ 11:30am MST). I’ll update it as the project progresses.

⇧ Plymouth taking a lot of time during boot Find likely processes based on snapshot in time  â‡©