Add restart_pre/restart_post support, also document RC_CMD

man/runscript.8

@@ -357,6 +357,9 @@ In a Gentoo Prefix installation, this variable contains the prefix
 offset. Otherwise it is undefined.
 .It Va RC_UNAME
 The result of `uname -s`.
+.It Va RC_CMD
+Name of the command like start, stop, restart, ...
+RC_CMD is one way to determine whether it's a restart or normal start/stop.
 .El
 .Sh FILES
 .Pp
@@ -444,6 +447,11 @@ depend()
     need ${_need}
 }
 
+restart_pre() {
+	# Verify a config and abort the restart in case it's not valid
+	...
+}
+
 start_pre()
 {
     # Ensure that our dirs are correct