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RE: OT:UNIX: Anyway to run this in the background and return to ca

From: <Jared.Still_at_radisys.com>
Date: Fri, 22 Aug 2003 17:39:25 -0800
Message-ID: <F001.005CC87D.20030822173925@fatcity.com>


Here's a rather standard way of doing a fork in Perl.

Also a nice little daemon. Works very well for Oracle utilities.

Jared

> package Daemon;
> use strict;
> use Carp;
> use POSIX;

> sub daemon {
> my($tries, $pid, $sess_id);
> {
> if ($pid = fork) { exit 0 } # exit parent
> if (defined($pid )) {

         close STDOUT;

> close STDIN;
> chdir('/');
> croak "Cannot detach from controlling terminal" unless $sess_id
= POSIX::setsid();
> return $pid;
> }
> if (++$tries>5 ) {
> die "fork failed after $tries attempts: $!\n"
> } else {
> sleep 3;
> redo;
> }
> }

>}

"Matthew Zito" <mzito_at_gridapp.com>
Sent by: ml-errors_at_fatcity.com
 08/22/2003 02:44 PM
 Please respond to ORACLE-L  

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        Subject:        RE: OT:UNIX: Anyway to run this in the background and return to ca


 

Errrm - this script doesn't do what I think you're trying to do. Perl starts, it forks a child process, the parent process "does a bunch of stuff", but the child process only runs ps once. Soooo, you end up with a zombie child process (until the parent is done with its business) and a parent process that is doing all the work.  

A better solution would be to reverse the ps and the "doing stuff". Let the child process do the dirty work and let the parent focus on either generating more children or status monitoring the existing children. You could use a loop that watches for the existence of a particular pid or has a set condition and add a SIGCHLD handler that will handle cleanup of the child and remove the loop condition.  

Thanks,
Matt

--
Matthew Zito
GridApp Systems
Email: mzito_at_gridapp.com
Cell: 646-220-3551
Phone: 212-358-8211 x 359
http://www.gridapp.com 
-----Original Message-----
Sent: Friday, August 22, 2003 2:04 PM
To: Multiple recipients of list ORACLE-L

#!/usr/bin/perl
use strict;
use bytes;
my $pid=0;
if (!defined ($pid=fork())) { die "Problem with cutlery:$!\n"}
elsif ($pid) { print "Do stuff here\n";
               waitpid($pid,0);
               print "Cutlery is back\n";
             }
else {
         open(SPY,"ps -ef|grep sqlplus|");
         while (<SPY>) {    print;}
       }
 
--
Mladen Gogala
Oracle DBA 
-----Original Message-----
Sent: Friday, August 22, 2003 1:25 PM
To: Multiple recipients of list ORACLE-L


$ORACLE_HOME/bin/sqlplus "/ as sysdba"  << EOD 
select ...... 
exit 
EOD 
echo "this is a test" 
ps -ef|grep sqlplus 
I wish to put that into a unix command but at the same time run it in the 
background and return back to the parent script to do some other stuff?
Anyone done this? 
 
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  INET: Jared.Still_at_radisys.com

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Received on Fri Aug 22 2003 - 20:39:25 CDT

Original text of this message

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