Add an example script where Redshift determines daytime

README.adoc

@@ -45,3 +45,10 @@ to the settings (see later).
 == Settings
 
 For settings, open the XFCE Settings Editor -> `night-mode` channel.
+
+=== Switch at a time specified by antoher program
+
+For example, to use http://jonls.dk/redshift/[Redshift] or another program to
+determine when it is night, use `xfce4-night-mode-redshift.sh` (or a modified
+version of it) instad of `xfce4-night-mode.sh` in "Generic Monitor plugin
+usage".

xfce4-night-mode-redshift.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+# XFCE Night Mode controlled by Redshift
+#
+# https://gitlab.com/bimlas/xfce4-night-mode (main repository)
+# https://github.com/bimlas/xfce4-night-mode (mirror, please star if you like the plugin)
+
+if ( LC_ALL='C' redshift -vo 2> /dev/null | grep "Period: Daytime" > /dev/null ); then
+  mode='day'
+else
+  mode='night'
+fi
+
+"$(dirname "$0")/xfce4-night-mode.sh" $mode | sed '/<tool>/,/<\/tool>/ d'
+echo "<tool>
+  Night mode defined by RedShift
+  Click to toggle mode for a while
+  </tool>"