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Top Forums Programming Problems with child comunicating with parent on fork() Post 302188447 by shamrock on Wednesday 23rd of April 2008 01:54:18 PM
Old 04-23-2008
It would be nice to see the code from the fork() function onwards. From the posted code it seems that the parent and child process are both reading from the pipe. That is incorrect as the parent should write to the pipe while the child reads from it. Owing to the atomicity of the parent writes it is guaranteed that the child process waits for data to be written to the pipe before pulling it out from its end.
 

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PCNTL_FORK(3)								 1							     PCNTL_FORK(3)

pcntl_fork - Forks the currently running process

SYNOPSIS
int pcntl_fork (void ) DESCRIPTION
The pcntl_fork(3) function creates a child process that differs from the parent process only in its PID and PPID. Please see your system's fork(2) man page for specific details as to how fork works on your system. RETURN VALUES
On success, the PID of the child process is returned in the parent's thread of execution, and a 0 is returned in the child's thread of execution. On failure, a -1 will be returned in the parent's context, no child process will be created, and a PHP error is raised. EXAMPLES
Example #1 pcntl_fork(3) example <?php $pid = pcntl_fork(); if ($pid == -1) { die('could not fork'); } else if ($pid) { // we are the parent pcntl_wait($status); //Protect against Zombie children } else { // we are the child } ?> SEE ALSO
pcntl_waitpid(3), pcntl_signal(3), setproctitle(3). PHP Documentation Group PCNTL_FORK(3)
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