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Groups > comp.lang.java.programmer > #20927

Re: single instance

From Martin Gregorie <martin@address-in-sig.invalid>
Newsgroups comp.lang.java.programmer
Subject Re: single instance
Date 2013-01-03 21:05 +0000
Organization UK Free Software Network
Message-ID <kc4rpu$4at$1@localhost.localdomain> (permalink)
References <iah6e8hb9ssp4q46ukh3scb81bjb9fdq1k@4ax.com> <sm7be8dvh8ulkncsrh3s5a1f0a0h3d6ah3@4ax.com> <ml38v8maw1s1$.1gx93ez99j3rq$.dlg@40tude.net>

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On Thu, 03 Jan 2013 09:56:27 -0800, Peter Duniho wrote:

> I would guess that Unix and Linux have similar OS-supported techniques
> (and may even be the same for those two).  So writing two, maybe three
> at the most, platform-specific solutions would give you cross-platform
> support for the vast majority of clients.
>
A common approach for *NIXen is to use a file with a known absolute 
pathname that contains the process PID. The clever trick is that the 
program that creates the file immediately closes and reopens it for 
reading and then deletes the file without closing it: this works because 
file deletion is deferred until there are no longer any processes that 
have the file open. When a process dies or is killed, all the files it 
had open are closed.

If the file exists and has a different pid to the checker, then another 
copy is running. There is no clean-up needed: if the user kills the 
program the file vanishes because it only remains in existence as long as 
at least one process has the file open.

As well as Linux and Unices, this works for a number of other OSen: its 
certainly good for BSB (and hence OS X), Stratus VOX and, IIRC, 
Microware's OS-9.


-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |

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Thread

single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-01 12:23 -0800
  Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-01 16:40 -0500
    Re: single instance Robert Tomsick <robert+usenet@tomsick.net> - 2013-01-03 01:20 -0500
  Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-03 00:55 -0800
    Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-03 19:31 -0800
      Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-03 19:49 -0800
      Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-03 19:56 -0800
        Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-04 12:18 -0500
          Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-04 10:22 -0800
            Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-04 13:44 -0500
              Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-04 11:03 -0800
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-04 14:12 -0500
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-05 21:56 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 19:22 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:23 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 20:43 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:47 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 20:51 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:24 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 20:46 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:58 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 21:08 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 21:19 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 21:31 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 21:41 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 22:00 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 22:11 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-07 00:23 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-02-24 18:20 -0500
                Re: single instance Joshua Cranmer <Pidgeot18@verizon.invalid> - 2013-01-06 21:39 -0600
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-07 00:30 -0500
                Re: single instance lipska the kat <lipskathekat@yahoo.co.uk> - 2013-01-07 08:53 +0000
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-02-24 18:18 -0500
                Re: single instance lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-25 08:31 +0000
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-02-24 18:17 -0500
                Re: single instance Lew <lewbloch@gmail.com> - 2013-01-06 17:32 -0800
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 20:47 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:53 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 21:01 -0500
          Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-05 21:59 -0500
            Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 19:34 -0500
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:00 -0500
  Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-03 07:12 -0800
    Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-03 09:56 -0800
      Re: single instance Martin Gregorie <martin@address-in-sig.invalid> - 2013-01-03 21:05 +0000
        Re: single instance Martin Gregorie <martin@address-in-sig.invalid> - 2013-01-03 22:08 +0000
        Re: single instance "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-01-05 12:48 +0000
          Re: single instance Martin Gregorie <martin@address-in-sig.invalid> - 2013-01-05 17:43 +0000
            Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-05 09:49 -0800
            Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-05 13:02 -0500
              Re: single instance Martin Gregorie <martin@address-in-sig.invalid> - 2013-01-05 20:29 +0000
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-05 19:07 -0800
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 20:04 -0500
            Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-05 21:40 -0500
    Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-05 22:10 -0500
      Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-05 19:49 -0800
        Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-05 23:09 -0500
          Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 11:00 -0500
            Re: single instance Lew <lewbloch@gmail.com> - 2013-01-06 09:41 -0800
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:41 -0500
        Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-15 22:51 -0800
          Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-15 23:12 -0800
            Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-15 23:49 -0800
          Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-15 23:16 -0800
            Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-15 23:52 -0800
            Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-16 08:46 -0800
              Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-16 10:46 -0800
                Re: single instance markspace <markspace@nospam.nospam> - 2013-01-16 13:01 -0800
                Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-16 17:10 -0800
          Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-15 23:50 -0800
            Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-16 00:13 -0800
              Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-16 02:48 -0800
                Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-16 07:28 -0800
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-16 10:46 -0800
                Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-16 16:53 -0800
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-16 23:44 -0800
                Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-17 07:03 -0800
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-17 14:25 -0800
                Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-17 16:31 -0800
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-17 22:11 -0800
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-17 22:36 -0800
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-16 13:34 -0500
          Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-16 08:45 -0800
          Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-16 13:29 -0500
            Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-16 17:14 -0800
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-16 20:20 -0500
              Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-16 23:52 -0800
              Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-17 01:44 -0800
        Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-18 01:47 -0800
          Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-18 20:50 -0800
            Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-20 00:53 -0800
              Re: single instance Lew <lewbloch@gmail.com> - 2013-01-20 12:00 -0800
                Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-20 13:33 -0800
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-02-24 18:12 -0500
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-20 21:33 -0500
      Re: single instance "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-01-06 13:34 +0000
  Re: single instance Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-01-04 10:26 -0800
    Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-04 14:04 -0500
  Re: single instance stledger@lanl.gov - 2013-01-16 14:51 -0800
    Re: single instance stledger@lanl.gov - 2013-01-16 15:09 -0800

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