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Date: Mon, 15 Dec 2003 13:28:50 -0800 (PST)
From: Don Lewis <truckman@FreeBSD.org>
To: cracauer@cons.org
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cc: cracauer@FreeBSD.org
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Subject: Re: truss issue
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On 15 Dec, Martin Cracauer wrote:
> Don Lewis wrote on Mon, Dec 15, 2003 at 01:13:58PM -0800: 

>> Hmn, I wonder if it would be cleaner to exec() the executable to be
>> traced in the parent process and run truss in the child ...
> 
> I think I misunderstand.  The parent is usually your login shell, you
> don't want that one to exec() anything.

If you type "truss foo" at the shell prompt, the shell will fork and
exec truss, which forks and execs foo.  When truss forks, the child
process is the one that execs foo, and the parent process watches what
the child process does.  My suggestion is to swap the roles of the
parent and child truss processes.  The parent truss process would be the
one that calls exec(), and the child process would be the one doing the
monitoring.  When the process being traced exits, the shell would
automagically get the correct exit status.

There are probably some complications that I'm overlooking, but ...