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OpenSolaris 2009.06 - man page for waitid (opensolaris section 2)

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),  sig-
       info.h(3HEAD), wait(3C), waitpid(3C), attributes(5), standards(5)

SunOS 5.11				    9 Jun 2004					waitid(2)


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