On Mon, Apr 7, 2008 at 11:04 PM, Michael Kerrisk
<mtk.manpages@xxxxxxxxxxxxxx> wrote:
>
> On Mon, Apr 7, 2008 at 6:16 PM, Justin Pryzby
> <justinpryzby@xxxxxxxxxxxxxxxxxxxxx> wrote:
> > Version: 2.79-2
> > File: /usr/share/man/man2/wait.2.gz
> >
> > What do people think of something like the attached change? While
> > working with Debian's cron package, I found that explicitly setting
> > the SIGCHLD action to SIG_IGN inhibits the creation of zombie
> > processes, even though kill(1) gives the "ignore" as the default
> > disposition.
> >
> > Consider the attached example program. Any of the following changes
> > will cause a zombie process to be visible in a ps -ef process listing:
> >
> > . remove the call to signal();
> > . change SIG_IGN to SIG_DFL;
> > . remove the sleep(1); (due to process scheduling, the zombie is only
> > sometimes visible);
> > . ???
> >
> > --- /usr/share/man/man2/wait.2.gz
> > +++ /tmp/wait2.gz.22000 2008-04-07 12:02:31.000000000 -0400
> > @@ -46,7 +46,7 @@
> > .\" Much other text rewritten
> > .\" 2005-05-10, mtk, __W* flags can't be used with waitid()
> > .\"
> > -.TH WAIT 2 2007-07-26 "Linux" "Linux Programmer's Manual"
> > +.TH WAIT 2 2008-04-07 "Linux" "Linux Programmer's Manual"
> > .SH NAME
> > wait, waitpid, waitid \- wait for process to change state
> > .SH SYNOPSIS
> > @@ -429,7 +429,7 @@
> >
> > POSIX.1-2001 specifies that if the disposition of
> > .B SIGCHLD
> > -is set to
> > +is set explicitly to
> > .B SIG_IGN
> > or the
> > .B SA_NOCLDWAIT
>
> I would not favor this. It suggests that there is the notion of
> "implicitly" setting the disposition to SIG_IGN, which of course there
> isn't. What I've instead done is added a sentence:
>
> Note that even though
Ooops -- I accidentally sent an incomplete draft.
The sentence I added was:
Note that even though the default disposition of SIGCHLD is
"ignore", explicitly
setting the disposition to SIG_IGN results in different treatement of zombie
children.
Seem okay?
Cheers,
Michael
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