Nicolas.Williams at Nicolas.Williams at
Wed Aug 7 03:48:34 EST 2002

I meant, what is the difference in behaviour in technical terms.

E.g., "the BSD pty master gets EOF as soon as all processes in the pty's
controlling process group exit, whereas on Linux the pty master EOFs
only when there are no open file descriptors for the pty."

And what server-side, user-level heuristic could "correct" for this



> -----Original Message-----
> From: Craig J Copi [mailto:cjc5 at]
> Sent: Tuesday, August 06, 2002 1:19 PM
> To: Williams, Nicolas
> Cc: openssh-unix-dev at
> Subject: Re: so-called-hang-on-exit 
> Nicolas.Williams at writes:
> >
> >What's the difference, again?
> Using the following test:
> #> ssh machinename
> #> (sleep 10; echo hi) &
> #> exit
> I get the following results.
> H == Hang, wait for sleep, print hi, then exit
> NH == Exit immediately (hi not printed)
> client\server |  Linux  | OpenBSD
> --------------+---------+--------
> Linux         |    H    |  NH
> OpenBSD       |    H    |  NH
> Using the following test:
> #> ssh machinename '(sleep 10; echo hi) &'
> I get the following results.
> client\server |  Linux  | OpenBSD
> --------------+---------+--------
> Linux         |    H    |  H
> OpenBSD       |    H    |  H
> Note:
> Linux == RH7.3 w/updates
> OpenBSD == 3.1 w/updates
> OpenSSH 3.4[p1] w/privsep running on test machines.
> So why does this happen.  People seem to expect the OpenBSD behavior
> eventhough you don't get the "hi" printed in the first test case.
> Craig

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