From: Vincent Lefevre <vincent@vinc17.net>
To: zsh-users@zsh.org
Subject: kill the LHS command of a pipe once the RHS command terminates
Date: Fri, 28 Jun 2019 13:04:30 +0200 [thread overview]
Message-ID: <20190628110430.GA13790@zira.vinc17.org> (raw)
With some commands I pipe the output to a pager, and when quitting
the pager, I want the command to terminate immediately (so that it
doesn't consume more resources) and want the shell prompt back.
Here are examples with "head -n 1" instead of a pager.
* With just a pipe:
zira% { echo foo; sleep 3; echo err >&2 } | head -n 1
foo
[wait for 3 seconds]
err
zira%
The issue is that when "head -n 1" terminates (just after "echo foo"),
the left-hand-side command is still running. Thus it still consumes
resources, and I also have to wait for the shell prompt, which is bad.
* With a process substitution:
zira% head -n 1 <(echo foo; sleep 3; echo err >&2)
foo
zira%
Here I get the shell prompt back immediately, which is good. But
the left-hand-side command is still running, so that it still
consumes resources; moreover, after the 3 seconds, I get
zira% err
In practice, one may want to redirect stderr to the pager too (not
always, though); this avoids this second issue, but not the first one,
which is that the left-hand-side command still consumes resources.
Does zsh provide a feature to kill the left-hand-side command in a
clean way (without a race condition, without a temporary file...)?
--
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
next reply other threads:[~2019-06-28 11:05 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-28 11:04 Vincent Lefevre [this message]
2019-06-28 11:38 ` Vincent Lefevre
2019-06-29 16:17 ` Bart Schaefer
2019-07-06 23:55 ` Vincent Lefevre
2019-07-07 4:54 ` Bart Schaefer
2019-07-09 10:08 ` Vincent Lefevre
2019-07-09 10:54 ` Vincent Lefevre
2019-07-29 15:23 ` Vincent Lefevre
2019-07-29 15:54 ` Bart Schaefer
2019-07-29 20:48 ` Vincent Lefevre
2019-07-30 0:00 ` Bart Schaefer
2019-07-30 0:17 ` Vincent Lefevre
[not found] <20190628110430.GA13790__36317.6205357135$1561719956$gmane$org@zira.vinc17.org>
2019-06-28 18:41 ` Stephane Chazelas
2019-06-29 1:24 ` Vincent Lefevre
2019-06-29 15:30 ` Stephane Chazelas
2019-07-06 23:49 ` Vincent Lefevre
2019-07-29 23:08 ` Vincent Lefevre
2019-07-29 23:15 ` Vincent Lefevre
2019-07-29 23:42 ` Bart Schaefer
2019-07-30 0:40 ` Vincent Lefevre
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