improve shutdown documentation

This fixes #290.

man/openrc-shutdown.8

@@ -17,15 +17,35 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl c , -cancel
+.Nm
+.Op Fl R , -reexec
+.Nm
+.Op Fl w , -write-only
+.Nm
 .Op Fl d , -no-write
 .Op Fl D , -dry-run
 .Op Fl H , -halt
+time
+.Nm
+.Op Fl d , -no-write
+.Op Fl D , -dry-run
 .Op Fl k , -kexec
+time
+.Nm
+.Op Fl d , -no-write
+.Op Fl D , -dry-run
 .Op Fl p , -poweroff
-.Op Fl R , -reexec
+time
+.Nm
+.Op Fl d , -no-write
+.Op Fl D , -dry-run
 .Op Fl r , -reboot
+time
+.Nm
+.Op Fl d , -no-write
+.Op Fl D , -dry-run
 .Op Fl s , -single
-.Op Fl w , -write-only
+time
 .Sh DESCRIPTION
 .Nm
 is the utility that communicates with
@@ -56,7 +76,7 @@ Stop all services, kill all processes and reboot the system.
 .It Fl s , -single
 Stop all services, kill all processes and move to single user mode.
 .It Fl w , -write-only
-Stop all services, kill all processes and move to single user mode.
+Wrrite a wtmp shutdown record and do nothing else.
 .El
 .Sh SEE ALSO
 .Xr openrc-init 8 ,

src/rc/openrc-shutdown.c

@@ -67,7 +67,15 @@ const char * const longopts_help[] = {
 	"write wtmp boot record and exit",
 	longopts_help_COMMON
 };
-const char *usagestring = NULL;
+const char *usagestring = "" \
+						   "Usage: openrc-shutdown -c | --cancel\n" \
+						   "   or: openrc-shutdown -R | --reexec\n" \
+						   "   or: openrc-shutdown -w | --write-only\n" \
+						   "   or: openmrc-shutdown -H | --halt time\n" \
+						   "   or: openrc-shutdown -K | --kexec time\n" \
+						   "   or: openrc-shutdown -p | --poweroff time\n" \
+						   "   or: openrc-shutdown -r | --reboot time\n" \
+						   "   or: openrc-shutdown -s | --single time";
 const char *exclusive = "Select one of "
 	"--cancel, --halt, --kexec, --poweroff, --reexec, --reboot, --single or \n"
 	"--write-only";