status of the hang-on-exit-bug

Ed Phillips ed at UDel.Edu
Wed Oct 24 01:19:46 EST 2001

On Tue, 23 Oct 2001, Markus Friedl wrote:

> Date: Tue, 23 Oct 2001 16:59:56 +0200
> From: Markus Friedl <markus at>
> To: Ed Phillips <ed at UDel.Edu>
> Cc: openssh-unix-dev at, openssh at
> Subject: status of the hang-on-exit-bug
> openssh's sshd currently tries to do what the rshd does:
> after a SIGCHLD the sshd waits for an EOF from the login shell on
> stdout/stderr. this is because we don't want to loose any data.
> you can avoid this problem by starting the remote command with
> stdin/out/err redirected to /dev/null.
> unlike sshd both telnetd and rlogind exit on SIGCHLD. however, this
> is because they don't care about lost data. but ssh needs to care.
> rlogin does not. this is why ssh hangs and rlogin does not.

Okay... that sounds like a nice feature - to wait for the shell to end
before having sshd exit.  So, this is the SIGCHLD race condition mentioned
earlier?  Has it been fixed (which version) or is it considered a

It's not clear from your post whether you are describing something that
needs to be fixed or something that is already fixed or something that is
not going to be fixed because it doesn't really need to be fixed.

Sorry for my thick skull...



Ed Phillips <ed at> University of Delaware (302) 831-6082
Systems Programmer III, Network and Systems Services
finger -l ed at for PGP public key

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