Re: wait for non-child PID

Re: wait for non-child PID

[Chet Ramey]

> > % wait 1
> > 
> > blocks forever.  (It is interruptible.)
> > 
> > bash detects that the PID is not child of the shell.
> 
> I'm glad that zsh's wait will wait on processes that aren't children of the
> shell.  Is there a reason that it shouldn't?

Because the shell will never get a SIGCHLD to notify it that the process
has changed state.  A process only gets SIGCHLD when its immediate children
change state.


-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
( ``Discere est Dolere'' -- chet)

Chet Ramey, CWRU    chet@po.CWRU.Edu    http://cnswww.cns.cwru.edu/~chet/

wait for non-child PID

[Tanaka Akira]

I heard that wait has a problem if the argument is non-child PID.

For example,

% wait 1

blocks forever.  (It is interruptible.)

bash detects that the PID is not child of the shell.

bash-2.04$ wait 1
bash: wait: pid 1 is not a child of this shell
-- 
Tanaka Akira

Re: wait for non-child PID

[Clint Adams]

> % wait 1
> 
> blocks forever.  (It is interruptible.)
> 
> bash detects that the PID is not child of the shell.

I'm glad that zsh's wait will wait on processes that aren't children of the
shell.  Is there a reason that it shouldn't?

Re: wait for non-child PID

[Tanaka Akira]

In article <20000726190953.A22895@scowler.net>,
  Clint Adams <schizo@debian.org> writes:

> I'm glad that zsh's wait will wait on processes that aren't children of the
> shell.  Is there a reason that it shouldn't?

A zsh can waits the process, but the zsh doesn't notice its status
change because the zsh is not the parent of it and SIGCHLD cannot
reached to the zsh.  Is it useful?
-- 
Tanaka Akira