Xmonad and Xmobar setup for laptop

Here I publish my Xmonad and Xmobar setup for the laptop. Key features of this setup is ability of the proper dynamic monitor setup: laptop screen + second HDMI connected monitor.

• Monitor can be connected and disconnected any time.
• Each monitor has its instance of Xmobar.
• Instances of the Xmobar are added/removed dynamically.

I use systemd service for the detection of the external monitor/screen attachment/detachment.

Screenshot

Sequence (logic)

1. I start all applets, notify daemon and system tray application (trayer) in the .xprofile.
   • It also launches displaymode script, which detects if the laptop lid is open or closed and whether HDMI monitor is attached or not. Depending on the condition it sets up appropriate displays configuration with xrandr.
2. In order to detect attachment or detachment of the screen I made my own systemd service for this event. (See chapter below).

• Both systemd service and displaymode script restart xmonad process when display setup is changed because xmonad dynamically spawns necessary number of xmobar instances on the screen.

Systemd service setup

Without desktop environment automatic detection of the attachment and detachment of the external monitor does not work. I took initial idea from here: Arch Linux forum. In order to implement this, three things are needed:

1. Script to detect monitor state and execute action
2. Systemd service using this script
3. UDEV rule which is triggered by the device event and launches this systemd service

1. The script

I created the script /usr/local/bin/hdmi-unplug with the following content: This script updates Xmonad or Qtile depending on the Xsession configuration.

#!/bin/sh

######################################
## /usr/local/bin/hdmi_unplug
######################################
X_USER=alexgum
export DISPLAY=:0
export XAUTHORITY=/home/$X_USER/.Xauthority
export DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
HDMI_STATUS=$(cat /sys/devices/pci0000:00/0000:00:08.1/0000:05:00.0/drm/card0/card0-HDMI-A-1/status)
LID_STATE=$(cat /proc/acpi/button/lid/LID/state | cut -d':' -f2 | tr -d ' ')

connect()
{   
    case $1 in
        "open")
            # I don't want automatic desktop extension on the output.
            # I prefer manual switching to the desired mode.
            xrandr --output eDP --primary --auto --output HDMI-A-0 --off
            ;;
        "closed")
            xrandr --output eDP --off --output HDMI-A-0 --primary --auto
            if [ ! -z "$(pgrep -fa Xsession | grep qtile)" ]
            then
                qtile-cmd -o cmd -f restart 2> /dev/null
            fi
            if [ ! -z "$(pgrep -fa Xsession | grep xmonad)" ]
            then
                echo " " > /tmp/displaymode #to display icons on Xmobar
                echo "HDMI" >> /tmp/displaymode
                xmonad --restart
            fi
            nitrogen --restore
            ;;
    esac
}

disconnect(){
    xrandr --output eDP --primary --auto --output HDMI-A-0 --off
    if [ ! -z "$(pgrep -fa Xsession | grep qtile)" ]
    then
        qtile-cmd -o cmd -f restart 2> /dev/null
    fi
    if [ ! -z "$(pgrep -fa Xsession | grep xmonad)" ]
    then
        echo " " > /tmp/displaymode # to display icons on Xmobar
        echo "default" >> /tmp/displaymode
        xmonad --restart
    fi
    nitrogen --restore
}

if [ "${HDMI_STATUS}" = "disconnected" ]; then
    disconnect
elif [ "${HDMI_STATUS}" = "connected" ]; then
    connect "${LID_STATE}"
fi

exit

2. The Systemd service

Then I created /etc/systemd/system/hdmi-unplug.service file with the following content:

[Unit]
Description=HDMI Monitor unplug

[Service]
Type=simple
RemainAfterExit=no
User=alexgum
ExecStart=/usr/local/bin/hdmi-unplug

[Install]
WantedBy=multi-user.target

3. UDEV rule

And, finally, UDEV rule /etc/udev/rules.d/95-hdmi-unplug.rules:

# My rule to automatically unplug external HDMI monitor when disconnected
ACTION=="change", KERNEL=="card0", SUBSYSTEM=="drm", RUN+="/usr/bin/systemctl start hdmi-unplug.service"

Xmonad.hs critical section

Full xmonad.hs configuration you can find here. Here is just show essential part of the code.

I use XMonad.Layout.IndependentScreens to detect number of screens. Then I put myLogHook in a separate definition (you can check it in the configuration file). It allows to make main part short and clean and I can easier redirect log to both xmobar pipes when they are open.

And then in the main function:

main = do
    nScreens <- countScreens
    if nScreens == 1
        then do 
            xmproc0 <- spawnPipe "xmobar -x 0 $HOME/.config/xmobar/xmobarrc"
            xmonad $ docks $ ewmh defaults {
                    manageHook = namedScratchpadManageHook scratchpads <+> manageHook defaults
                    , layoutHook = layoutHook defaults
                    , logHook = currentWorkspaceOnTop >> myLogHook xmproc0
                    }
        else do
            xmproc0 <- spawnPipe "xmobar -x 0 $HOME/.config/xmobar/xmobarrc"
            xmproc1 <- spawnPipe "xmobar -x 1 $HOME/.config/xmobar/xmobarrc1"
            xmonad $ docks $ ewmh defaults {
                    manageHook = namedScratchpadManageHook scratchpads <+> manageHook defaults
                    , layoutHook = layoutHook defaults
                    , logHook = currentWorkspaceOnTop >> myLogHook xmproc0 >> myLogHook xmproc1
                    }

Each time when xmobar is restarted, it re-detects number of displays and spawns necessary number of bars.

The only exception is mirror mode (xrandr --output eDP-1 --primary --auto --output HDMI-1 --auto --same-as eDP-1), then no xmobar restart is needed because I want to keep main screen xmobar being projected.