When you see a comment like this, it means it is intentionally
undocumented.
It is the current mechanism shutdown uses. It could use a different
mechanism in the future. It is done this way so that noone else depends
on it. If you document this user-visible, they will come to depend on
it, then we cannot be agile and change the mechanism later.
I don't think we don't want that, so no.
If you persist at going through the tree you'll find about 20 other
instances of this. It is a fairly common pattern.
- case 'l': /* Undocumented; used by shutdown. */
> Hi,
>
> The following diff adds missing documentation for the -l option of
> reboot(8) as its done in NetBSD.
>
> Bye,
> Jan
>
> Index: reboot.8
> ===================================================================
> RCS file: /cvs/src/sbin/reboot/reboot.8,v
> retrieving revision 1.50
> diff -u -p -r1.50 reboot.8
> --- reboot.8 3 Sep 2016 14:25:05 -0000 1.50
> +++ reboot.8 25 Mar 2019 14:12:48 -0000
> @@ -30,7 +30,7 @@
> .\"
> .\" @(#)reboot.8 8.1 (Berkeley) 6/9/93
> .\"
> -.Dd $Mdocdate: September 3 2016 $
> +.Dd $Mdocdate: March 25 2019 $
> .Dt REBOOT 8
> .Os
> .Sh NAME
> @@ -39,9 +39,9 @@
> .Nd stopping and restarting the system
> .Sh SYNOPSIS
> .Nm halt
> -.Op Fl dnpq
> +.Op Fl dlnpq
> .Nm reboot
> -.Op Fl dnq
> +.Op Fl dlnq
> .Sh DESCRIPTION
> The
> .Nm halt
> @@ -70,6 +70,10 @@ capturing the state of a corrupted or mi
> See
> .Xr savecore 8
> for information on how to recover this dump.
> +.It Fl l
> +Suppress sending a message via
> +.Xr syslog 3
> +before halting or restarting.
> .It Fl n
> Prevent file system cache from being flushed.
> This option should probably not be used.
> Index: reboot.c
> ===================================================================
> RCS file: /cvs/src/sbin/reboot/reboot.c,v
> retrieving revision 1.38
> diff -u -p -r1.38 reboot.c
> --- reboot.c 22 Aug 2017 00:30:16 -0000 1.38
> +++ reboot.c 25 Mar 2019 14:03:43 -0000
> @@ -94,7 +94,7 @@ main(int argc, char *argv[])
> case 'd':
> howto |= RB_DUMP;
> break;
> - case 'l': /* Undocumented; used by shutdown. */
> + case 'l':
> lflag = 1;
> break;
> case 'n':
> @@ -272,7 +272,7 @@ restart:
> void
> usage(void)
> {
> - fprintf(stderr, "usage: %s [-dn%sq]\n", __progname,
> + fprintf(stderr, "usage: %s [-dln%sq]\n", __progname,
> dohalt ? "p" : "");
> exit(1);
> }
>
