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Date: Thu, 19 May 2011 06:27:54 +0100
Message-ID: <BANLkTi=aztXC2DaLB-6g-FSXUzTg2txStw@mail.gmail.com>
Subject: Re: Process Execution from Cygwin Shells
From: Andy Koppe <andy DOT koppe AT gmail DOT com>
To: cygwin AT cygwin DOT com
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On 19 May 2011 05:58, Sravan Bhamidipati wrote:
> Steps to reproduce:
> 1. Open "Process Monitor" and filter for events of type "Operation"
> and value "Process Create".
> 2. Open a Cygwin shell (using cygwin.bat or mintty or rxvt): bash or ksh, e.g.
> 3. Type any command that is not a shell built-in, say "clear" or "cmd".
> 4. Notice that "Process Monitor" captured two process creation events
> related to the invoked command: a new child shell and another of the
> invoked command.

The first is the shell forking itself, the second is the forked
process invoking exec() to run the new program.

> This seems very strange to me. The behavior applies even when
> executing a Shell script. I noticed identical behavior when using
> MinGW Shell as well.

No surprise there, since the MinGW Shell (i.e. MSYS) is little more
than an old Cygwin version.

> Shells in Unix-based OSs don't behave this way.

Yep, because there exec() doesn't create a new process, it just
replaces the program in the current process. Windows can't do that,
hence Cygwin has to emulate it by creating a new process.

> Can something be done about it?

Nope.

Andy

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