Re: (bash) How (really!) does the "current job" get determined?

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Sujet : Re: (bash) How (really!) does the "current job" get determined?
De : richard.nospam (at) *nospam* gmail.invalid (Richard Harnden)
Groupes : comp.unix.shell
Date : 07. Oct 2024, 23:32:58
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <ve1niq$1rv6h$1@dont-email.me>
References : 1 2 3 4 5 6 7
User-Agent : Mozilla Thunderbird
On 04/10/2024 23:48, Christian Weisgerber wrote:
 I'm curious myself.  That said, here's something I stumbled across
recently:
      background job &
     ...
     kill %1     # clean up
 What happens if the background job has already terminated on its
own accord before we reach the kill(1)?  Not much, because with job
control, the shell knows that no such job exists.  If you do this
with "kill $!", you signal that PID, which no longer refers to the
intended process and may in fact have been reused for a different
process.
 
There would have to be a very long time in your '...' part for a pid to get reused. I guess you could ps | grep and check the command name is what you expect.
You can 'kill -0 <pid>' (or %<job>) for 'could I signal <pid>', rather that actually sending a signal - it returns non-zero if it can't.
If the job finishes before you wait then the process is gone, ie not zombied, so ksh/bash must keep track of the wait status. The job is also gone, so only wait <pid> will get you the correct exit status.

Date Sujet#  Auteur
4 Oct 24 * (bash) How (really!) does the "current job" get determined?33Kenny McCormack
4 Oct 24 `* Re: (bash) How (really!) does the "current job" get determined?32Kaz Kylheku
4 Oct 24  `* Re: (bash) How (really!) does the "current job" get determined?31Kenny McCormack
4 Oct 24   `* Re: (bash) How (really!) does the "current job" get determined?30Kaz Kylheku
4 Oct 24    +* Expand your mind (Was: (bash) How (really!) does the "current job" get determined?)2Kenny McCormack
5 Oct 24    i`- Re: Expand your mind (Was: (bash) How (really!) does the "current job" get determined?)1Kaz Kylheku
4 Oct 24    `* Re: (bash) How (really!) does the "current job" get determined?27Christian Weisgerber
4 Oct 24     `* Re: (bash) How (really!) does the "current job" get determined?26Janis Papanagnou
5 Oct 24      `* Re: (bash) How (really!) does the "current job" get determined?25Christian Weisgerber
5 Oct 24       +* Re: (bash) How (really!) does the "current job" get determined?2Kaz Kylheku
10 Oct 24       i`- Re: (bash) How (really!) does the "current job" get determined?1Kaz Kylheku
5 Oct 24       +- Re: (bash) How (really!) does the "current job" get determined?1Keith Thompson
5 Oct 24       +* Re: (bash) How (really!) does the "current job" get determined?13Kenny McCormack
5 Oct 24       i+* Re: (bash) How (really!) does the "current job" get determined?11Christian Weisgerber
5 Oct 24       ii`* pid ranges (Was: (bash) How (really!) does the "current job" get determined?)10Kenny McCormack
7 Oct 24       ii `* Re: pid ranges (Was: (bash) How (really!) does the "current job" get determined?)9Janis Papanagnou
7 Oct 24       ii  +- Re: pid ranges (Was: (bash) How (really!) does the "current job" get determined?)1marrgol
7 Oct 24       ii  `* Re: pid ranges (Was: (bash) How (really!) does the "current job" get determined?)7Kenny McCormack
7 Oct 24       ii   `* Re: pid ranges (Was: (bash) How (really!) does the "current job" get determined?)6Janis Papanagnou
7 Oct 24       ii    `* Re: pid ranges5Richard Kettlewell
7 Oct 24       ii     `* [OT] PIDs for Linux threads (was Re: pid ranges)4Janis Papanagnou
7 Oct 24       ii      +- Re: [OT] PIDs for Linux threads (was Re: pid ranges)1Kenny McCormack
7 Oct 24       ii      +- Re: [OT] PIDs for Linux threads (was Re: pid ranges)1Lew Pitcher
7 Oct 24       ii      `- Re: PIDs for Linux threads (was Re: pid ranges)1Lawrence D'Oliveiro
6 Oct 24       i`- Re: (bash) How (really!) does the "current job" get determined?1Kaz Kylheku
7 Oct 24       +* Re: (bash) How (really!) does the "current job" get determined?5Janis Papanagnou
7 Oct 24       i`* Re: (bash) How (really!) does the "current job" get determined?4Kenny McCormack
7 Oct 24       i `* Re: (bash) How (really!) does the "current job" get determined?3Janis Papanagnou
7 Oct 24       i  `* bash/ksh differences (fg and other job control commands) (Was: (bash) How (really!) does the "current job" get determined?)2Kenny McCormack
7 Oct 24       i   `- Re: bash/ksh differences (fg and other job control commands) (Was: (bash) How (really!) does the "current job" get determined?)1Janis Papanagnou
7 Oct 24       +- Re: (bash) How (really!) does the "current job" get determined?1Helmut Waitzmann
8 Oct 24       +- Re: (bash) How (really!) does the "current job" get determined?1Richard Harnden
8 Oct 24       `- Re: (bash) How (really!) does the "current job" get determined?1Kaz Kylheku

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