Re: proced: ppid of process ID 0 can be 0

[Giorgos Keramidas <keramida@ceid.upatras.gr>]

On Mon, 22 Dec 2008 11:43:15 +0100, "Juanma Barranquero" <lekktu@gmail.com> wrote:
> On Mon, Dec 22, 2008 at 09:54, Harald Hanche-Olsen <hanche@math.ntnu.no> wrote:
>
>> FWIW, on FreeBSD there is process 0 (the swapper), and various kernel
>> processes have process 0 as their parent.
>
> There's no problem with a process having ppid = 0. But there's a
> problem with processes having ppid = pid. Is that the case in FreeBSD?

Yes this is the case:

$ ps -xao pid,ppid,args | sed -n -e 1p -e /sed/d -e /kernel/p
  PID  PPID COMMAND
    0     0 [kernel]
$

There are several processes with ppid == 0, and process 0 has pid == ppid:

  PID  PPID COMMAND
    0     0 [kernel]
    1     0 /sbin/init --
    2     0 [g_event]
    3     0 [g_up]
    4     0 [g_down]
    5     0 [xpt_thrd]
    6     0 [sctp_iterator]
    7     0 [pfpurge]
    8     0 [pagedaemon]
    9     0 [vmdaemon]
   10     0 [audit]
   11     0 [idle]
   12     0 [intr]
   13     0 [yarrow]
   14     0 [usb0]
   15     0 [usbtask-hc]
   16     0 [usbtask-dr]
   17     0 [usb1]
   18     0 [usb2]
   19     0 [usb3]
   20     0 [usb4]
   21     0 [usb5]
   22     0 [usb6]
   23     0 [acpi_thermal]
   24     0 [acpi_cooling0]
   25     0 [pagezero]
   26     0 [bufdaemon]
   27     0 [vnlru]
   28     0 [syncer]
   29     0 [softdepflush]
 1019     0 [md0]