improve documentation

diff --git a/relay-cmd b/relay-cmd
index 6ed7eae14038783711b5ea416b0ffc6ce0687886..0da382e27af0b290f17305ca403642801f996157 100755 (executable)
--- a/relay-cmd
+++ b/relay-cmd
@@ -6,14 +6,19 @@ usage() {
   cat <<EOF
 Usage: relay-cmd poweroff|poweron|reboot HOSTNAME|CHANNEL [RELAY_ID]
 
-For CHANNEL and RELAY_ID, run hidusb-relay-cmd and hidusb-relay-cmd state.
-I recommend writing a config to use HOSTNAME instead. Config is /etc/relay-cmd.conf
-Example config:
-
-# This config is just bash that gets sourced.
+RELAY_ID is not needed if only 1 relay device is connected.  To
+understand CHANNEL and RELAY_ID, run hidusb-relay-cmd and
+hidusb-relay-cmd state.  I recommend writing a config in
+/etc/relay-cmd.conf , then using HOSTNAME instead of CHANNEL and
+RELAY_ID. It serves as documentation of what you connected the relay
+to. Example config:
+
+# This config is just sourced from bash, so make sure its valid bash.
 # relay_id is not needed if only 1 relay is connected.
 cephserver3_channel=1
 cephserver3_relay_id=HURTM
+cephserver2_channel=2
+cephserver2_relay_id=HURTM
 EOF
   exit $1
 }
@@ -29,6 +34,7 @@ if [[ -e /etc/relay-cmd.conf ]]; then
   source /etc/relay-cmd.conf
 fi
 
+# we know HOSTNAME is given if it doesn't start with a number.
 if [[ $chan != [0-9]* ]]; then
   chan_var=${chan}_channel
   chan=${!chan_var}