wait3(3C)						   Standard C Library Functions 						 wait3(3C)

NAME

       wait3, wait4 - wait for process to terminate or stop

SYNOPSIS

       #include <sys/wait.h>
       #include <sys/time.h>
       #include <sys/resource.h>

       pid_t wait3(int *statusp, int options, struct rusage *rusage);

       pid_t wait4(pid_t pid, int *statusp, int options, struct rusage *rusage);

DESCRIPTION

       The  wait3() function delays its caller until a signal is received or one of its child processes terminates or stops due to tracing. If any
       child process has died or stopped due to tracing and this has not already been reported, return is immediate, returning the process ID  and
       status  of one of those children. If that child process has died, it is discarded. If there are no children, -1 is returned immediately. If
       there are only running or stopped but reported children, the calling process is blocked.

       If statusp is not a null pointer, then on return from a successful wait3() call, the status of the child process is stored in  the  integer
       pointed to by statusp. *statusp indicates the cause of termination and other information about the terminated process in the following man-
       ner:

	 o  If the low-order 8 bits of *statusp are equal to 0177, the child process has stopped; the 8 bits higher up from the low-order  8  bits
	    of *statusp contain the number of the signal that caused the process to stop. See signal.h(3HEAD).

	 o  If	the  low-order	8  bits of *statusp are non-zero and are not equal to 0177, the child process terminated due to a signal; the low-
	    order 7 bits of *statusp contain the number of the signal that terminated the process. In addition, if the low-order  seventh  bit	of
	    *statusp (that is, bit 0200) is set, a ``core image'' of the process was produced; see signal.h(3HEAD).

	 o  Otherwise,	the child process terminated due to an exit() call; the 8 bits higher up from the low-order 8 bits of *statusp contain the
	    low-order 8 bits of the argument that the child process passed to exit(); see exit(2).

       The options argument is constructed from the bitwise inclusive OR of zero or more of the following flags, defined in <sys/wait.h>:

       WNOHANG	       Execution of the calling process is not suspended if status is not immediately available for any child process.

       WUNTRACED       The status of any child processes that are stopped, and whose status has not yet been reported since they stopped, are also
		       reported to the requesting process.

       If  rusage is not a null pointer, a summary of the resources used by the terminated process and all its children is returned. Only the user
       time used and the system time used are currently available. They are returned in the ru_utime and ru_stime, members of  the  rusage  struc-
       ture, respectively.

       When  the  WNOHANG  option is specified and no processes have status to report, wait3() returns 0. The WNOHANG and WUNTRACED options may be
       combined by the bitwise OR operation of the two values.

       The wait4() function is an extended interface.  With a pid argument of 0, it is equivalent to wait3(). If pid has  a  nonzero  value,  then
       wait4()	returns  status  only  for  the indicated process ID, but not for any other child processes. The status can be evaluated using the
       macros defined by wait.h(3HEAD).

RETURN VALUES

       If wait3() or wait4() returns due to a stopped or terminated child process, the process ID of the child is returned to the calling process.
       Otherwise, -1 is returned and errno is set to indicate the error.

       If  wait3()  or wait4() return due to the delivery of a signal to the calling process, -1 is returned and errno is set to EINTR. If WNOHANG
       was set in options, it has at least one child process specified by pid for which status is not available, and status is not  available  for
       any process specified by pid, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.

       The  wait3()  and wait4() functions return 0 if WNOHANG is specified and there are no stopped or exited children, and return the process ID
       of the child process if they return due to a stopped or terminated child process. Otherwise, they return -1 and set errno to  indicate  the
       error.

ERRORS

       The wait3() and wait4() functions will fail and return immediately if:

       ECHILD	       The calling process has no existing unwaited-for child processes.

       EFAULT	       The statusp or rusage arguments point to an illegal address.

       EINTR	       The function was interrupted by a signal. The value of the location pointed to by statusp is undefined.

       EINVAL	       The value of options is not valid.

       The wait4() function may fail if:

       ECHILD	       The process specified by pid does not exist or is not a child of the calling process.

       The  wait3()and	wait4()  functions  will  terminate  prematurely,  return  -1,	and  set errno to EINTR upon the arrival of a signal whose
       SA_RESTART bit in its flags field is not set (see sigaction(2)).

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       kill(1), exit(2), waitid(2), waitpid(3C),  getrusage(3C), signal(3C), signal.h(3HEAD), wait(3C), wait.h(3HEAD), proc(4)

NOTES

       If a parent process terminates without waiting on its children, the initialization process (process ID = 1) inherits the children.

       The wait3() and	wait4() functions are automatically restarted when a process receives a signal	while  awaiting  termination  of  a  child
       process, unless the SA_RESTART bit is not set in the flags for that signal.

SunOS 5.10							    3 Mar 1995								 wait3(3C)