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From: Bart Schaefer <schaefer@brasslantern.com>
To: Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: $PPID not updated when the PPID changes (parent killed)
Date: Mon, 17 May 2021 16:15:24 -0700	[thread overview]
Message-ID: <CAH+w=7bywj1X1fyPLgpmo_OoqBEN8PjEDxDeKP-tMR_O4g04tg@mail.gmail.com> (raw)
In-Reply-To: <YKLttAsFd4bl9waS@fullerene.field.pennock-tech.net>

On Mon, May 17, 2021 at 3:27 PM Phil Pennock
<zsh-workers+phil.pennock@spodhuis.org> wrote:
>
>   The initial parent process ID; that is, the process ID of the process
>   which created this shell process, at the time that it did so.

This is pretty close to what I was thinking.  Does "at the time"
really add anything?

>   Just as for $$, the value is only set for the original shell and does
>   not dynamically change for implicit subshells (as created for (list)
>   and for pipelines).

Except (list) is an explicit subshell, isn't it?

> It's an attempt to be clearer that "if you run zsh within zsh,
> that's not a subshell, sure _that_ gets $$ and $PPID reset".

Indeed.  I'm tempted to say

  Just as with $$, the value is updated only within a new shell
  that increases $SHLVL, and not in other subshells.

And then clarify "a new shell" under SHLVL if necessary, but I hope it isn't.

Aside, it's a bit odd that SHLVL isn't read-only.  Even assorted Bash
tutorials found by online search treat it as immutable (statements
like "$dog is only available at SHLVL 2") despite that it can be
arbitrarily messed with.


  reply	other threads:[~2021-05-17 23:15 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-16 15:24 Vincent Lefevre
2021-05-16 18:37 ` Bart Schaefer
2021-05-17 20:26   ` Vincent Lefevre
2021-05-17 21:00     ` Bart Schaefer
2021-05-17 22:27       ` Phil Pennock
2021-05-17 23:15         ` Bart Schaefer [this message]
2021-05-18  0:30           ` Phil Pennock
2021-05-18  1:14             ` Bart Schaefer
2021-05-18  8:28             ` Vincent Lefevre
2021-05-18  8:15           ` Vincent Lefevre
2021-05-18 14:53             ` Bart Schaefer
2021-05-19  4:25               ` Bart Schaefer
2021-07-18 23:10                 ` Lawrence Velázquez
2021-05-18 15:18           ` Mikael Magnusson
2021-05-18 16:14             ` Peter Stephenson
2021-05-18 18:20               ` Bart Schaefer
2021-05-18 17:37           ` Martijn Dekker
2021-05-18 18:08             ` Bart Schaefer
2021-05-18 19:40               ` Martijn Dekker
2021-05-18 18:06           ` Stephane Chazelas
2021-05-18 18:12             ` Bart Schaefer
2021-05-18 18:50               ` $SHLVL origin (was: $PPID not updated when the PPID changes (parent killed)) Stephane Chazelas
2021-05-18 15:56         ` $PPID not updated when the PPID changes (parent killed) Stephane Chazelas

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