Daftar Isi

• waitpid PID,FLAGS

  Waits for a particular child process to terminate and returns the pid ofthe deceased process, or -1 if there is no such child process. On somesystems, a value of 0 indicates that there are processes still running.The status is returned in $? and ${^CHILD_ERROR_NATIVE}. If you say

   use POSIX ":sys_wait_h";
   
   #...
   
   do {
   
   $kid = waitpid(-1, WNOHANG);
   
   } while $kid > 0;
   

  then you can do a non-blocking wait for all pending zombie processes.Non-blocking wait is available on machines supporting either thewaitpid(2) or wait4(2) syscalls. However, waiting for a particularpid with FLAGS of 0 is implemented everywhere. (Perl emulates thesystem call by remembering the status values of processes that haveexited but have not been harvested by the Perl script yet.)

  Note that on some systems, a return value of -1 could mean that childprocesses are being automatically reaped. See perlipc for details,and for other examples.

  Portability issues: waitpid in perlport.