waitid(2)							   System Calls 							 waitid(2)

NAME

       waitid - wait for child process to change state

SYNOPSIS

       #include <wait.h>

       int waitid(idtype_t idtype, id_t id, siginfo_t *infop, int options);

DESCRIPTION

       The  waitid() function suspends the calling process until one of its child processes changes state. It records the current state of a child
       in the  structure pointed to by infop. It returns immediately if a child process changed state prior to the call.

       The idtype and  id arguments specify which children  waitid() is to wait for, as follows:

	   o	  If  idtype is P_PID, waitid() waits for the child with a process ID equal to (pid_t)id.

	   o	  If idtype is P_PGID,	waitid() waits for any child with a process group ID equal to (pid_t)id.

	   o	  If idtype is P_ALL, waitid() waits for any child and id is ignored.

       The options argument is used to specify which state changes waitid() is to wait for. It is formed by bitwise OR operation  of  any  of  the
       following flags:

       WCONTINUED    Return the status for any child that was stopped and has been continued.

       WEXITED	     Wait for process(es) to exit.

       WNOHANG	     Return immediately.

       WNOWAIT	     Keep the process in a waitable state.

       WSTOPPED      Wait for and return the process status of any child that has  stopped upon receipt of a signal.

       WTRAPPED      Wait for traced process(es) to become trapped or reach a breakpoint (see ptrace(3C)).

       The  infop  argument  must  point to a siginfo_t structure, as defined in siginfo.h(3HEAD). If waitid() returns because a child process was
       found that satisfies the conditions indicated by the arguments idtype and options, then the structure pointed to by infop will be filled by
       the system with the status of the process. The si_signo member will always be equal to SIGCHLD.

       One  instance  of  a  SIGCHLD signal is queued for each child process whose status has changed. If waitid() returns because the status of a
       child process is available and WNOWAIT was not specified in options, any pending SIGCHLD signal associated with	the  process  ID  of  that
       child process is discarded. Any other pending SIGCHLD signals remain pending.

RETURN VALUES

       If  waitid()  returns due to a change of state of one of its children and  WNOHANG was not used,  0 is returned.  Otherwise, -1 is returned
       and  errno is set to indicate the error. If WNOHANG was used,  0 can be returned (indicating no	error);  however,  no  children  may  have
       changed state if info->si_pid is 0.

ERRORS

       The waitid() function will fail if:

       ECHILD	 The set of processes specified by idtype and id does not contain any unwaited processes.

       EFAULT	 The infop argument points to an illegal address.

       EINTR	 The waitid() function was interrupted due to the receipt of a signal by the calling process.

       EINVAL	 An invalid value was specified for options, or idtype and id specify an invalid set of processes.

USAGE

       With  options equal to WEXITED | WTRAPPED, waitid() is equivalent to waitpid(3C). With idtype equal to P_ALL and options equal to WEXITED |
       WTRAPPED, waitid() is equivalent to wait(3C).

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       Intro(2),  exec(2),  exit(2),  fork(2),	pause(2),  sigaction(2),  ptrace(3C),	signal(3C),   siginfo.h(3HEAD),   wait(3C),   waitpid(3C),
       attributes(5), standards(5)

SunOS 5.11							    9 Jun 2004								 waitid(2)