vincentbernat.i3wm-configuration/bin/polybar

#!/bin/sh

export DPI=$(xrdb -query | sed -nE 's/^Xft\.dpi:\s*//p')
export HEIGHT=$((20 * DPI / 96))

MONITORS=$(xrandr --current --listactivemonitors | sed -nE 's/ *([0-9]+): [+*]*([^ ]*).*/\2/p')
PRIMARY=$(xrandr --current --listactivemonitors | sed -nE 's/ *([0-9]+): [+]?[*]([^ ]*).*/\2/p')
PRIMARY=${PRIMARY:-${MONITORS%% *}}

case $(echo $MONITORS | wc -w) in
    1)
        MONITOR=$PRIMARY polybar --reload alone &
        ;;
    *)
        MONITOR=$PRIMARY polybar --reload primary &
        for MONITOR in ${MONITORS}; do
            [ $MONITOR != $PRIMARY ] || continue
            MONITOR=$MONITOR polybar --reload secondary &
        done
        ;;
esac