adding example runit-style service directory

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

examples/var_service/dhcp_if_pinger/run

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+delay=67
+
+if=${PWD##*/dhcp_}
+if=${if%%_pinger}
+
+if test -f "$0.log"; then
+	tail -999 "$0.log" >"$0.log.new"
+	mv "$0.log.new" "$0.log"
+fi
+
+test -f "/var/service/dhcp_$if/dhcp_$if.out" || exec env - sleep "$delay"
+. "/var/service/dhcp_$if/dhcp_$if.out"
+test x"$router" != x"" || exec env - sleep "$delay"
+
+#echo "`date '+%Y-%m-%d %H:%M:%S'` Testing ping -c3 $router" >>"$0.log"
+ping -c3 "$router" && exec env - sleep "$delay"
+
+echo "`date '+%Y-%m-%d %H:%M:%S'` Restarting /var/service/dhcp_$if" >>"$0.log"
+sv t "/var/service/dhcp_$if"
+
+exec env - sleep "$delay"