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Re: background processes (was HOW2 capture time of power-failure?)

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On 2014-11-03, not.socialnetwork@gmail.com <not.socialnetwork@gmail.com> wrote:
> In article <m2tdmr$hi8$1@dont-email.me>, Joe Beanfish <joebeanfish@nospam.duh> wrote: 
>
>> On Thu, 30 Oct 2014 08:32:11 +0000, not.socialnetwork wrote:
>> > But I want to also test/confirm the general method, for apps which don't
>> > have the special facilities of ogg123, that you were able to use.
>> > 
>> > I need to read-up on 'starting/stopping background/foreground'
>> > processes,
>> > after I've cleared some other chaos here.
>> 
>> Use "&" to start something in the background.
>> Use "$!" to get the pid of the last background process started.
>> Use "wait" to wait for a (or all) background process(es) to finish.
>> Use "kill" to stop a background process.
>> Here's something to start playing with:
>> 
>> #!/bin/sh
>> echo "foreground pid $$ starting"
>> (echo "background started";sleep 5;echo "background finished") &
>> bgpid=$!
>> sleep 1
>> # wait around for background process to finish before quitting
>> #echo "waiting for background pid $bgpid"
>> #wait $bgpid
>> # stop background process before quitting
>> echo "killing background pid $bgpid"
>> kill $bgpid
>> echo "foreground pid $$ finished"
>
> --- Nice tutorial. Thanks.
>
> I've spent quite some time trying to analyse your code.
> The very 1st line [of linux syntax] is problematic for me:
>  apparently the EVALUATION of <pid $$> [what ever that is]
>  is embedded in the reporting of <pid $$>.
Not Linux. bash
man bash
$$ is the pid (program identifier) of the current program ( the script
in this case).
So that line produces the output
foreground pid 783 starting
where 783 is actually the number for the script itself. 

>  
> IMO <linux syntax> has too many hidden-hooks to catch you;
> like special rules for the 17th Tuesday of a non-leap-year.

Not Linux. bash. And not hidden, but you do need to learn it. 

AFter this your comments degenerate.
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HOW2 capture time of power-failure? not.socialnetwork@gmail.com - 2014-10-26 17:38 +0000
  Re: HOW2 capture time of power-failure? Ian Malcolm <See.My.Sig.for.email@totally.invalid> - 2014-10-26 18:26 +0000
    Re: HOW2 capture time of power-failure? not.socialnetwork@gmail.com - 2014-10-27 18:10 +0000
      Re: HOW2 capture time of power-failure? Gordon Henderson <gordon+usenet@drogon.net> - 2014-10-27 18:29 +0000
        Re: HOW2 capture time of power-failure? not.socialnetwork@gmail.com - 2014-10-28 21:26 +0000
      Re: HOW2 capture time of power-failure? William Unruh <unruh@invalid.ca> - 2014-10-28 04:56 +0000
        Re: HOW2 capture time of power-failure? Dom <domafp@blueyonder.co.uk> - 2014-10-28 06:29 +0000
          Re: HOW2 capture time of power-failure? William Unruh <unruh@invalid.ca> - 2014-10-28 06:41 +0000
            Re: HOW2 capture time of power-failure? not.socialnetwork@gmail.com - 2014-10-29 00:12 +0000
  Re: HOW2 capture time of power-failure? William Unruh <unruh@invalid.ca> - 2014-10-26 19:23 +0000
    Re: HOW2 capture time of power-failure? spam-no-spam@Freeola.net.invalid (Windmill) - 2014-11-04 13:19 +0000
      Re: HOW2 capture time of power-failure? William Unruh <unruh@invalid.ca> - 2014-11-05 21:56 +0000
        Re: HOW2 capture time of power-failure? Joe Beanfish <joebeanfish@nospam.duh> - 2014-11-06 14:12 +0000
        Re: HOW2 capture time of power-failure? nba@users.sourceforge.net (Niels Baggesen) - 2014-11-06 16:15 +0100
          Re: HOW2 capture time of power-failure? William Unruh <unruh@invalid.ca> - 2014-11-06 16:00 +0000
        Re: HOW2 capture time of power-failure? spam-no-spam@Freeola.net.invalid (Windmill) - 2014-11-06 20:37 +0000
      Re: HOW2 capture time of power-failure? Joe Beanfish <joebeanfish@nospam.duh> - 2014-11-06 14:13 +0000
  Re: HOW2 capture time of power-failure? andrew@cucumber.demon.co.uk (Andrew Gabriel) - 2014-10-26 20:28 +0000
  Re: HOW2 capture time of power-failure? Joe Beanfish <joebeanfish@nospam.duh> - 2014-10-27 13:17 +0000
  Re: HOW2 capture time of power-failure? Jean-David Beyer <jeandavid8@verizon.net> - 2014-10-28 13:43 -0400
    Re: HOW2 capture time of power-failure? Ant <ant@zimage.comANT> - 2014-10-29 08:18 -0700
  Re: HOW2 capture time of power-failure? Joe Beanfish <joebeanfish@nospam.duh> - 2014-10-29 13:28 +0000
    Re: HOW2 capture time of power-failure? not.socialnetwork@gmail.com - 2014-10-30 08:32 +0000
      background processes (was HOW2 capture time of power-failure?) Joe Beanfish <joebeanfish@nospam.duh> - 2014-10-30 13:16 +0000
        Re: background processes (was HOW2 capture time of power-failure?) not.socialnetwork@gmail.com - 2014-11-03 03:25 +0000
          Re: background processes (was HOW2 capture time of power-failure?) "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2014-11-02 23:34 -0500
          Re: background processes (was HOW2 capture time of power-failure?) William Unruh <unruh@invalid.ca> - 2014-11-03 08:25 +0000
          Re: background processes (was HOW2 capture time of power-failure?) Martin Gregorie <martin@address-in-sig.invalid> - 2014-11-03 12:56 +0000
            Re: background processes (was HOW2 capture time of power-failure?) not.socialnetwork@gmail.com - 2014-11-06 19:19 +0000
              Re: background processes (was HOW2 capture time of power-failure?) Martin Gregorie <martin@address-in-sig.invalid> - 2014-11-07 02:36 +0000
              Re: background processes (was HOW2 capture time of power-failure?) Joe Beanfish <joebeanfish@nospam.duh> - 2014-11-07 14:28 +0000
                Re: background processes (was HOW2 capture time of power-failure?) not.socialnetwork@gmail.com - 2014-11-08 03:32 +0000

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