Path: csiph.com!goblin2!goblin1!goblin.stu.neva.ru!usenet.stanford.edu!not-for-mail
From: Chet Ramey <chet.ramey@case.edu>
Newsgroups: gnu.bash.bug
Subject: Re: process substitution error handling
Date: Thu, 6 Aug 2020 11:14:40 -0400
Organization: ITS, Case Western Reserve University
Lines: 41
Approved: bug-bash@gnu.org
Message-ID: <mailman.1027.1596726900.2739.bug-bash@gnu.org>
References: <20200420051508.GA2359844@zx2c4.com> <7496b183-2db3-6c03-6074-928adcd08f45@case.edu> <CAHmME9pzOY_0EJ69y9wt6r-Jh3frZpV8XdFC6zG5EOkZ99h-1A@mail.gmail.com> <ac79e09f-b4e3-5368-87c1-b6e7147809e2@case.edu> <CAHmME9qNjO+LMxB8py2MDpS2Oprv1mRndgfTXQfXNWyHuwzmjg@mail.gmail.com> <9b358a76-4867-41b9-5a3a-c1892c76b8ee@case.edu> <d27db25d-e533-3fa8-b85e-6dfbe6adefb3@case.edu>
Reply-To: chet.ramey@case.edu
NNTP-Posting-Host: lists.gnu.org
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Cc: chet.ramey@case.edu, bug-bash@gnu.org, "Demi M. Obenour" <demiobenour@gmail.com>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Envelope-to: bug-bash@gnu.org
Autocrypt: addr=chet.ramey@case.edu; prefer-encrypt=mutual; keydata= mQGiBEEOsGwRBACFa0A1oa71HSZLWxAx0svXzhOZNQZOzqHmSuGOG92jIpQpr8DpvgRh40Yp AwdcXb8QG1J5yGAKeevNE1zCFaA725vGSdHUyypHouV0xoWwukYO6qlyyX+2BZU+okBUqoWQ koWxiYaCSfzB2Ln7pmdys1fJhcgBKf3VjWCjd2XJTwCgoFJOwyBFJdugjfwjSoRSwDOIMf0D /iQKqlWhIO1LGpMrGX0il0/x4zj0NAcSwAk7LaPZbN4UPjn5pqGEHBlf1+xDDQCkAoZ/VqES GZragl4VqJfxBr29Ag0UDvNbUbXoxQsARdero1M8GiAIRc50hj7HXFoERwenbNDJL86GPLAQ OTGOCa4W2o29nFfFjQrsrrYHzVtyA/9oyKvTeEMJ7NA3VJdWcmn7gOu0FxEmSNhSoV1T4vP2 1Wf7f5niCCRKQLNyUy0wEApQi4tSysdz+AbgAc0b/bHYVzIf2uO2lIEZQNNt+3g2bmXgloWm W5fsm/di50Gm1l1Na63d3RZ00SeFQos6WEwLUHEB0yp6KXluXLLIZitEJLQwQ2hldCBSYW1l eSAoQ2FzZSBzdGFuZGFyZCkgPGNoZXQucmFtZXlAY2FzZS5lZHU+iF8EExECAB8FAkPi19EC GwMHCwkIBwMCAQMVAgMDFgIBAh4BAheAAAoJELtYafBk6nSrelkAn31Gsuib7GcCZHbv5L5t VKYR9LklAJ4hzUHKA49Z0QXR+qCb80osIcmPSbkBDQRBDrBvEAQAkK6TAOKBEM+EC4j6V/7o /riVZqcgU5cid2qG9TXdwNtD9a3kvA/ObZBO93sX59wc6Bnwo4VJxsOmMlpGrAjJsxNwg3QH akEtf8LXRbVpj5xStdmBdQZUhIQyalo/2/TZq5OijtddUQcL5cs70hTv/FpT3wUvr2Xr8rjF 41IFEz8AAwcD/A0CZEGlzIrT5WCBnl6xBog/8vKiUCbarByat3d1mL6DbizvKNXQRTC9E/vE dENAWCQCjr75Bu55xT8n3SXGtWdDC5xmZ/P3OBYORP8yl8H8I1FIosWOFirbIeYdZPq8SPD1 HL+EXo9zSiHVrrZRJ19ooCKKbSdXHFCY+aJG+0KZiEkEGBECAAkFAkEOsG8CGwwACgkQu1hp 8GTqdKvjcACfZlkVCDwaz/NTO9cy3t69oWpVPNwAnRwe0qk/WL/gfhH346xh5B3HFbFN
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.11.0
In-Reply-To: <9b358a76-4867-41b9-5a3a-c1892c76b8ee@case.edu>
Content-Language: en-US
Received-SPF: pass client-ip=129.22.103.227; envelope-from=chet.ramey@case.edu; helo=mpv1-2015.case.edu
X-Spam_score_int: -43
X-Spam_score: -4.4
X-Spam_bar: ----
X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=ham autolearn_force=no
X-Spam_action: no action
X-BeenThere: bug-bash@gnu.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Bug reports for the GNU Bourne Again SHell <bug-bash.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/bug-bash>, <mailto:bug-bash-request@gnu.org?subject=unsubscribe>
List-Archive: <https://lists.gnu.org/archive/html/bug-bash>
List-Post: <mailto:bug-bash@gnu.org>
List-Help: <mailto:bug-bash-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/bug-bash>, <mailto:bug-bash-request@gnu.org?subject=subscribe>
X-Mailman-Original-Message-ID: <d27db25d-e533-3fa8-b85e-6dfbe6adefb3@case.edu>
X-Mailman-Original-References: <20200420051508.GA2359844@zx2c4.com> <7496b183-2db3-6c03-6074-928adcd08f45@case.edu> <CAHmME9pzOY_0EJ69y9wt6r-Jh3frZpV8XdFC6zG5EOkZ99h-1A@mail.gmail.com> <ac79e09f-b4e3-5368-87c1-b6e7147809e2@case.edu> <CAHmME9qNjO+LMxB8py2MDpS2Oprv1mRndgfTXQfXNWyHuwzmjg@mail.gmail.com> <9b358a76-4867-41b9-5a3a-c1892c76b8ee@case.edu>
Xref: csiph.com gnu.bash.bug:16718

On 8/6/20 10:48 AM, Chet Ramey wrote:

>> Perhaps another, clunkier, proposal would be to add `wait -s` so that
>> the wait builtin also waits for process substitutions and returns
>> their exit codes and changes $?. The downside would be that scripts
>> now need to add a "wait" after all of above such loops, but on the
>> upside, it's better than the current problematic situation.
> 
> You can already do this. Since process substitution sets $!, you can
> keep track of all of the process substitutions of interest and wait
> for as many of them as you like. `wait' will return their statuses
> and set $? for you.

I should have also mentioned that while bash-5.0 requires you to wait
for these process substitutions one at a time, in between their creation,
bash-5.1 will allow you to save $! and wait for them later:

$ cat x2
: <(sleep 5; exit 1)
P1=$!

: <(sleep 5; exit 2)
P2=$!

: <(sleep 5; exit 3)
P3=$!

wait $P1 ; echo $?
wait $P2 ; echo $?
wait $P3 ; echo $?
$ ../bash-5.1-alpha/bash x2
1
2
3


-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
		 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/