From: Bart Schaefer <schaefer@brasslantern.com>
To: "Zsh Hackers' List" <zsh-workers@zsh.org>
Subject: Re: Another bug when suspending pipelines
Date: Fri, 16 Sep 2016 15:25:07 -0700 [thread overview]
Message-ID: <160916152507.ZM26599@torch.brasslantern.com> (raw)
In-Reply-To: <20160916215241.0b1531d7@ntlworld.com>
On Sep 16, 9:52pm, Peter Stephenson wrote:
} Subject: Re: Another bug when suspending pipelines
}
} On Fri, 16 Sep 2016 11:38:01 -0700
} Bart Schaefer <schaefer@brasslantern.com> wrote:
} > The parent has to manage all three of these jobs, because it can't
} > hand off the already-forked "sleep 7" to the newly-forked brace job.
} > It has to arrange that the brace job can be sent a SIGCONT on "fg"
} > but not actually do anything until the "sleep 7" has finished; I
} > believe that's handled by the "synch" pipes and hidden reads; in any
} > case, it works.
}
} The parent shell "simply" waits for the non-shell processes that were
} forked directly from the parent shell on the right of the pipeline and
} restarts the forked shell to run the rest (which may, of course, include
} other external processes) when those have finished.
Hm. That means that if you *backgound* the "sleep" and bother looking
with "ps", you will see a process that is in T state while the shell
claims it is running.
I suppose that's worked fine for the last lo these many years, but does
it not mean that an external "kill -CONT" can cause the expected order
of events to be violated?
} > * makes the tail of the brace expression into a process group which
} > becomes the tty leader, and
} > * writes a byte on the synch pipe to wake it up.
}
} This all happened in one go when the shell was forked.
Maybe it shouldn't. Ugh.
prev parent reply other threads:[~2016-09-16 22:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20160916123306eucas1p1f4349b727ebdfb64b4947c9d210457e1@eucas1p1.samsung.com>
2016-09-16 12:33 ` Peter Stephenson
[not found] ` <CGME20160916164752eucas1p1add32b4825e126def7b3317c07731342@eucas1p1.samsung.com>
2016-09-16 16:47 ` Peter Stephenson
2016-09-16 18:38 ` Bart Schaefer
2016-09-16 20:52 ` Peter Stephenson
2016-09-16 22:25 ` Bart Schaefer [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=160916152507.ZM26599@torch.brasslantern.com \
--to=schaefer@brasslantern.com \
--cc=zsh-workers@zsh.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/zsh/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).