DMARC-Filter:	OpenDMARC Filter v1.4.2 delorie.com 597Bdt5T3577653
Authentication-Results:	delorie.com; dmarc=pass (p=none dis=none) header.from=cygwin.com
Authentication-Results:	delorie.com; spf=pass smtp.mailfrom=cygwin.com
DKIM-Filter:	OpenDKIM Filter v2.11.0 delorie.com 597Bdt5T3577653
Authentication-Results:	delorie.com;
	dkim=pass (1024-bit key, unprotected) header.d=cygwin.com header.i=@cygwin.com header.a=rsa-sha256 header.s=default header.b=mIQIjrB7
X-Recipient:	archive-cygwin AT delorie DOT com
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org B274E3858C53
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1759837193;
	bh=ct70gdfCOR91u4QQZkmb8NigKfwoQr2uaI6HaEGP95o=;
	h=Date:Subject:To:List-Id:List-Unsubscribe:List-Archive:List-Post:
	List-Help:List-Subscribe:From:Reply-To:From;
	b=mIQIjrB76Kcj3w5rCGBTqT/U84X3gFaz3PsZowa5tRvBpvbxd8Yl06DolTXrqefin
	L09ixssqSZtyAadyzrpUmyUTxZx6OAnmhzeRvmTdgljiXqAlrdW3XFsTqy4vtbZUBR
	/80WcU4zNI4Z6PZqfml/rTkPG3rq3y7H7QOvKzxk=
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.4.2 sourceware.org F34133858CD1
ARC-Filter:	OpenARC Filter v1.0.0 sourceware.org F34133858CD1
ARC-Seal:	i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1759837131; cv=none;
	b=fswfyz0Tcsz3WaJ5XK8PhKoLV4DIpsVJB0dU9e+Lq08HoUCZYJbHWS1dvzyv4HpV2P+964simK8GpimUrz5QQQX2GXZsHnmaHM9oW8tfw9Q8h7lOMb+CcnQDfYSt530jLWCWirrI3/CqaOEMagojLdvg5GiAd/BYAXxSO5GYF10=
ARC-Message-Signature:	i=1; a=rsa-sha256; d=sourceware.org; s=key;
	t=1759837131; c=relaxed/simple;
	bh=8277RtqUwUNL322td8UShNiU6ZIVmRQ0uLbPEFAqTFQ=;
	h=DKIM-Signature:MIME-Version:From:Date:Message-ID:Subject:To;
	b=GoEWjCW1yBF3TVzTrAt8sFMDeZ0RpPBYlDGwr3Jk1HpDpeSvxX81wmaaXcOvytia7ND1iYYOIl9e+YIQ6s0tXbNkp5jaF6h3BQppx2TvXastKf7pDa8INqoRzM/vQA9kWnD3p4g6nfiZQYoMhvz2nCmNCOF9giiIAu0wmN1gxBo=
ARC-Authentication-Results:	i=1; server2.sourceware.org
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org F34133858CD1
X-Google-DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed;
	d=1e100.net; s=20230601; t=1759837129; x=1760441929;
	h=to:subject:message-id:date:from:mime-version:x-gm-message-state
	:from:to:cc:subject:date:message-id:reply-to;
	bh=aNxv+wlJPMbTXi+j93B+evf/cyvdMc6RCUBDeVeW3h0=;
	b=SYjH02/7ZUVy9x8JA+x0oQFdlvV/jGEtuscG56Hp4mDskLVonf6sRP2sqEwd6FDhFP
	0Wpbny2tx5Xr9a0MIY4bMcsij4tPwQ5EKSfxNla9om3SmZMAjQZgJ5Ky1/hV+2mbAlNr
	sZ6GMzM0DjXmGAT2YNs5ZxBgYK0naTJLv9TnowSbuEZo8yJDJZMZSlZzLgwmR5la8pug
	l4h0T4Kzq73XxAjpsyT0+zKyw7scxU5zps1C7MTI9Q7stfQdd7Kn7ufcxLp0kyNg1KqO
	A73XpZPajjtZlYuTBMFRw8xeCKTBO+mrVg9LhdibApuwyQRLCo58wY7dt7BOJsWrToj9
	I0qQ==
X-Gm-Message-State:	AOJu0YwOdmmi62RYzOtkuCJeGe9db93ASA4tpNKhcmyL6udMZOx4p4P9
	q2sltujbjnGOLhrrt9VzyJbsBBMWo0Cs25CJvwVZlPhO7GVq3jKDgXYRuriw2Esd6/5qnSA0dwY
	mah6MM/epGP5BPbODWuXxkBw6zOWbKh6jvUGL3Yc=
X-Gm-Gg:	ASbGncuA40Dq4Qbntz9b9t4gCAA7sKcMYU9/xC/+srglxZngDyasi9WJpGFKsHqRo4h
	8y61kc8q4brearyfmzvSb8zuI/1sq3+70KwyEwj8AIJ1X1hlCx0aUMao/MU7epCtro8xE+1Y13t
	pEPaCdRvwQPQNFZwM2WhJhGIlr05QYWVopes4cOyDx1dgVzLAVuy2I8CbCqSVSbcABnejh9/KBD
	Nn2tCdE/vJ4SarfAnYkV8HOj1ICeS2LzAFAIUiaoA==
X-Google-Smtp-Source:	AGHT+IHfCoHUJJarVL52C2J8T73RwxRiZoguL+0ZOHOkvSoeaKJTT1Wlz5FCqGZrHy/mEQwvk3TJIjqRlZDRSUjA7jM=
X-Received:	by 2002:a05:6512:6cf:b0:55f:435e:36bd with SMTP id
	2adb3069b0e04-58cb69145a0mr4749551e87.0.1759837128798; Tue, 07 Oct 2025
	04:38:48 -0700 (PDT)
MIME-Version:	1.0
Date:	Tue, 7 Oct 2025 12:38:37 +0100
X-Gm-Features:	AS18NWBsW7DNp4hxZCqO6QUCkbcQedA4fdkSmw0vQ1fjSrZ70Wv89zmIYQ8qJRQ
Message-ID:	<CANgSWMMdLZa=aN79XgJwYSHyX87bDzcmjEjWTeQL54aybS934A@mail.gmail.com>
Subject:	job control in cygwin bash
To:	cygwin AT cygwin DOT com
X-BeenThere:	cygwin AT cygwin DOT com
X-Mailman-Version:	2.1.30
List-Id:	General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Archive:	<https://cygwin.com/pipermail/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe:	<https://cygwin.com/mailman/listinfo/cygwin>,
	<mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From:	Vadym Krevs via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	Vadym Krevs <vkrevs AT gmail DOT com>
Sender:	"Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>

Hi.

I've a question regarding job control in cygwin bash.

Below is a simple program that prints out the process id of itself.

    C:\builds>cat a.c
    #include <stdio.h>
    #include <process.h>

    int main(int argc, char ** argv)
    {
            printf("pid=%d\n", _getpid());
            return 0;
    }

Compiling and running it in foreground from cygwin bash works as expected:

    user AT host /cygdrive/c/builds
    $ cl a.c
    Microsoft (R) C/C++ Optimizing Compiler Version 19.44.35217 for x86
    Copyright (C) Microsoft Corporation.  All rights reserved.

    a.c
    Microsoft (R) Incremental Linker Version 14.44.35217.0
    Copyright (C) Microsoft Corporation.  All rights reserved.

    /out:a.exe
    a.obj

    user AT host /cygdrive/c/builds
    $ ./a
    pid=2352


However, if I start it in background and attempt to get back the pid
of the started process via $!, the result is not what one would
expect. The actual process pid printed out from my program differs
from what cygwin bash thinks is "process ID of the job most recently
placed into the background".

    user AT host /cygdrive/c/builds
    $ ./a &
    [1] 15909

    user AT host /cygdrive/c/builds
    $ pid=27008
    echo $!
    15909
    [1]+  Done                    ./a


So my question is - is this a cygwin bash quirk (i.e. the fact that $!
is not the pid of the started process) caused by how fork/process
startup is implemented in cygwin? I have tried reading
https://cygwin.com/cygwin-ug-net/highlights.html#ov-hi-process but
could not see anything relevant aside from "Job control works as
expected in shells that support it." in the Signals section. Is there
any way to get the actual process pid?

Many thanks in advance,
Vadym

-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple

- Raw text -