vincentbernat.i3wm-configuration/bin/xsettingsd-setup

#!/bin/sh

# Don't try to guess DPI. For a laptop, we don't want the same DPI as
# for an external screen. Just hardcode stuff...
case $(hostname),$(xrandr --current | \
                          sed -n 's/\([^ ]*\) connected .*[0-9][0-9]*x[0-9][0-9]*+[0-9][0-9]*+[0-9][0-9]* .*/\1/p' | \
                          sort | tr '\n' ':') in
    zoro,eDP1:)         dpi=144 ;;
    zoro,eDP-1:)        dpi=144 ;;
    zoro,eDP-1:HDMI-2:) dpi=144 ;;
    zoro,eDP-1:DP-1:)   dpi=144 ;;
    neo,HDMI-1:HDMI-2:) dpi=96 ;;
    neo,*)              dpi=192 ;;
    *)                  dpi=96 ;;
esac

# Get xsettingsd PID
pid=$(xprop -name xsettingsd _NET_WM_PID 2> /dev/null | awk '{print $NF}')

change() {
    # Build xsettingsd.local
    {
        cat  ~/.config/awesome/xsettingsd
        echo Xft/DPI $(( $1*1024 ))
        echo Xft/RGBA \"$( [ $1 -gt 144 ] && echo none || echo rgb )\"
        echo Gdk/WindowScalingFactor $(( $1/96 ))
        echo Gdk/UnscaledDPI $(( $1*1024/($1/96) ))
    } > ~/.xsettingsd

    # Signal xsettingsd
    if [ x"$pid" = x ]; then
        xsettingsd -c ~/.xsettingsd &
    else
        kill -HUP $pid
    fi
}

if [ x"$pid" != x ]; then
    # Change a first time to a DPI that will trigger a scale factor
    # change (notably, Firefox needs that).
    change $(( $dpi * 2 ))
    sleep 1
fi
change $dpi

# Also use xrdb for very old stuff (you know, LibreOffice)
echo Xft.dpi: $dpi | xrdb -merge