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pcntl_wait ( int &$status [, int $options = 0 ] ) : int

wait��ǰ��̵�ִ��ֱ��һ��ӽ��˳��յ�һ��ź�Ҫ��жϵ�ǰ��̻��һ��źŴ�� һ��ӽ��ڵ��ô˺��ʱ�Ѿ��˳��׳ƽ�ʬ��̣��˺��̷��ء��ӽ��ʹ�õ��ϵͳ��Դ�� ͷš��wait��ϵͳ�Ϲ��ϸ�淶��鿴��ϵͳ��wait��2��ֲᡣ

Note:
��ͬ��-1��Ϊ��pid ��ֵ��û��options��pcntl_waitpid() ��

status

pcntl_wait()��洢״̬��Ϣ��status ��ϣ��ͨ��status��ص�״̬��Ϣ��º�� pcntl_wifexited(), pcntl_wifstopped(), pcntl_wifsignaled(), pcntl_wexitstatus(), pcntl_wtermsig()�Լ� pcntl_wstopsig()��ȡ��ֵ��

options

��Ĳ��ϵͳ��BSD��ϵͳ��ʹ��wait3��ṩ��ѡ��options ��û��ṩ��wait��ᱻ��ϵͳ��á��wait3��ã��ṩ�� options��κ�Ч��options��ֵ��0 ��"��"��嶼��Ч��

**`options`��ֵ**
WNOHANG	��û��ӽ��˳��̷��ء�
WUNTRACED	�ӽ��Ѿ��˳��״̬δ��ʱ��ء�

pcntl_wait()��˳��ӽ��̽��̺ţ��ʱ��-1,��ṩ�� WNOHANG��Ϊoption��wait3��õ�ϵͳ��û�п��ӽ��ʱ��0��

pcntl_fork() - �ڵ�ǰ��̵�ǰλ�ò��֧��ӽ��̣��ע��fork�Ǵ��һ��ӽ��̣��̺��ӽ�� fork��λ�ÿ�ʼ��¼��ִ�У��ͬ��Ǹ��ִ�й��У��õ��fork��ֵΪ�ӽ�� ţ��ӽ��̵õ��0��
pcntl_signal() - ��װһ��źŴ��
pcntl_wifexited() - ��״̬��Ƿ��һ��˳��
pcntl_wifstopped() - ��ӽ��̵�ǰ�Ƿ��Ѿ�ֹͣ
pcntl_wifsignaled() - ��ӽ��״̬��Ƿ��ĳ��źŶ��ж�
pcntl_wexitstatus() - ��һ��жϵ��ӽ��̵ķ��ش��
pcntl_wtermsig() - ��ص��ӽ��жϵ��ź�
pcntl_wstopsig() - ��ص��ӽ��ֹͣ��ź�
pcntl_waitpid() - �ȴ��򷵻�fork��ӽ��״̬

pcntl_wait