Re: ssh and netcat

Josef Wolf wrote:
I can get rid of this error message by deleting the "exec" keywords from
the above script. But this effectively ignores the error.

So the question is: what causes this "Killed by signal X"? Is it some sort
of incompatibility between ssh and netcat?

The "outer" ssh command sends a SIGHUP to the proxycommand when it shuts down (some versions of netcat don't check for the closure of their stdin/stdout and would hang around forever).

By default, if ssh is killed by a signal it reports which one, which is what you're seeing (on Linux, 1=SIGHUP, 2=SIGINT).

Or am I using ssh and/or netcat
in a way it was not designed for? Any ideas how to properly get rid of this

You can either keep doing what you're doing (without the "exec", the ssh command has a parent shell, and the shell catches the SIGHUP but it does keep the shell process around for the duration of the connection) or tell ssh to be quiet and not report the signal (change "exec ssh foo" to "exec ssh -q foo").

Darren Tucker (dtucker at
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Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.