cvs commit: perlfaq perlfaq8.pod

cvsuser     02/06/20 21:33:43

  Modified:    .        perlfaq8.pod
  Log:
  * How do I start a process in the background?
  
  	+ added double fork example that used to be in perlfunc's entry
  	for fork.
  
  	+ mentioned the IGNORE value for $SIG{CHLD}
  
  Revision  Changes    Path
  1.9       +18 -2     perlfaq/perlfaq8.pod
  
  Index: perlfaq8.pod
  ===================================================================
  RCS file: /cvs/public/perlfaq/perlfaq8.pod,v
  retrieving revision 1.8
  retrieving revision 1.9
  diff -u -w -r1.8 -r1.9
  --- perlfaq8.pod	16 May 2002 12:41:42 -0000	1.8
  +++ perlfaq8.pod	21 Jun 2002 04:33:43 -0000	1.9
  @@ -1,6 +1,6 @@
   =head1 NAME
   
  -perlfaq8 - System Interaction ($Revision: 1.8 $, $Date: 2002/05/16 12:41:42 $)
  +perlfaq8 - System Interaction ($Revision: 1.9 $, $Date: 2002/06/21 04:33:43 $)
   
   =head1 DESCRIPTION
   
  @@ -375,9 +375,25 @@
   
   =item Zombies
   
  -You have to be prepared to "reap" the child process when it finishes
  +You have to be prepared to "reap" the child process when it finishes.
   
       $SIG{CHLD} = sub { wait };
  +    
  +    $SIG{CHLD} = 'IGNORE';
  +    
  +You can also use a double fork. You immediately wait() for your 
  +first child, and the init daemon will wait() for your grandchild once 
  +it exits.
  +
  +	unless ($pid = fork) {
  +		unless (fork) {
  +            exec "what you really wanna do";
  +            die "exec failed!";
  +        	}
  +        exit 0;
  +    	}
  +    waitpid($pid,0);
  +
   
   See L<perlipc/"Signals"> for other examples of code to do this.
   Zombies are not an issue with C<system("prog &")>.