From: Stephane Chazelas <stephane.chazelas@gmail.com>
To: Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: "echo | ps -j $(:) | cat | cat | cat" runs components in different process groups
Date: Sun, 25 Mar 2018 08:38:53 +0100 [thread overview]
Message-ID: <20180325073853.GA7561@chaz.gmail.com> (raw)
In-Reply-To: <20180323161612.GB4857@chaz.gmail.com>
2018-03-23 16:16:13 +0000, Stephane Chazelas:
[...]
> - the first pipeline component must be a builtin or compound command
To clarify, as explained by Bart, it doesn't have to be builtin.
It's more easily reproducible with builtins as they exit quickly
but one just needs a command that exits before the command
substitution as in:
sleep 1 | ps -j $(sleep 2) | cat|cat|cat...
Another side effect is that
echo test | tee $(uname) | sleep 10 | cat
cannot be aborted with ^C as only "cat" is in foreground (echo
gone, tee (soon gone too) and sleep on their own process group).
Also, ^Z suspends cat only causing a deadlock.
That's probably a worse problem and could explain the similar
lock ups I sometimes experience in zsh.
> - the second component must have a command substitution in the
> arguments (OK when in targets of redirections).
[...]
Following-up on my previous email, that means:
$ n=1; echo $((++n)) | cat; echo $n
2
2
$ n=1; echo > $((++n)) | cat; echo $n
1
Which looks a bit inconsistent.
--
Stephane
prev parent reply other threads:[~2018-03-25 7:38 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-23 16:16 Stephane Chazelas
2018-03-23 23:36 ` Bart Schaefer
2018-03-24 5:19 ` Bart Schaefer
2018-03-24 8:05 ` Joey Pabalinas
2018-03-24 17:34 ` Stephane Chazelas
2018-03-24 22:23 ` Bart Schaefer
2018-03-25 7:00 ` Stephane Chazelas
2018-03-25 8:26 ` Stephane Chazelas
2018-03-25 7:48 ` Stephane Chazelas
2018-03-25 18:09 ` Stephane Chazelas
2018-03-27 10:17 ` Stephane Chazelas
2018-03-24 22:09 ` Bart Schaefer
2018-04-10 11:45 ` Peter Stephenson
2018-04-10 13:59 ` Peter Stephenson
2018-04-11 22:10 ` Bart Schaefer
2018-04-12 16:23 ` Peter Stephenson
2018-04-15 16:23 ` Stephane Chazelas
2018-04-15 17:38 ` Bart Schaefer
2018-04-15 18:58 ` Stephane Chazelas
2018-04-17 5:39 ` Bart Schaefer
2018-04-17 9:19 ` Peter Stephenson
2018-04-17 16:09 ` Bart Schaefer
2018-04-17 16:27 ` Bart Schaefer
2018-04-17 16:35 ` Peter Stephenson
2018-04-17 17:52 ` Bart Schaefer
2018-04-19 9:40 ` Peter Stephenson
2018-04-20 9:28 ` Forking earlier for background code Peter Stephenson
2018-04-20 10:01 ` Peter Stephenson
2018-04-20 12:54 ` Vin Shelton
[not found] ` <CGME20180420132008eucas1p1c297624e870975cd892c74254970faab@eucas1p1.samsung.com>
2018-04-20 13:20 ` Peter Stephenson
2018-04-20 16:01 ` Vin Shelton
2018-04-23 8:29 ` Peter Stephenson
2018-05-01 9:23 ` Peter Stephenson
[not found] ` <F3A62E38-24E2-4A62-8E19-F54C9B81E9E5@kba.biglobe.ne.jp>
2018-04-23 13:52 ` "echo | ps -j $(:) | cat | cat | cat" runs components in different process groups Peter Stephenson
2018-04-23 14:03 ` Peter Stephenson
[not found] ` <CGME20180423140859eucas1p2591bf1422614209979d4890383268c37@eucas1p2.samsung.com>
2018-04-23 14:08 ` Peter Stephenson
2018-04-23 15:29 ` Jun T.
2018-04-18 6:29 ` Stephane Chazelas
2018-04-18 16:33 ` Bart Schaefer
2018-04-10 9:53 ` Peter Stephenson
2018-03-25 7:38 ` Stephane Chazelas [this message]
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