Linux Command Reference

Name

wait3, wait4 — wait for process to change state, BSD style

Synopsis

#define _BSD_SOURCE
                /* Or #define _XOPEN_SOURCE 500 for wait3() */
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>

`pid_t wait3(`	int *	`status`,
	int	`options`,
	struct rusage *	`rusage)`;

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

DESCRIPTION

The wait3() and wait4() system calls are similar to waitpid(2), but additionally return resource usage information about the child in the structure pointed to by rusage.

Other than the use of the rusage argument, the following wait3() call:

    wait3(status, options, rusage);

is equivalent to:

    waitpid(−1, status, options);

Similarly, the following wait4() call:

    wait4(pid, status, options, rusage);

is equivalent to:

    waitpid(pid, status, options);

In other words, wait3() waits of any child, while wait4() can be used to select a specific child, or children, on which to wait. See wait(2) for further details.

If rusage is not NULL, the struct rusage to which it points will be filled with accounting information about the child. See getrusage(2) for details.

RETURN VALUE

As for waitpid(2).

ERRORS

As for waitpid(2).

CONFORMING TO

4.3BSD

NOTES

Including <sys/time.h> is not required these days, but increases portability. (Indeed, <sys/resource.h> defines the rusage structure with fields of type struct timeval defined in <sys/time.h>.)

Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
and Copyright (c) 2004 by Michael Kerrisk (mtk-manpages@gmx.net)

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the source, must acknowledge the copyright and authors of this work.
License.

Modified Sat Jul 24 13:32:44 1993 by Rik Faith (faith@cs.unc.edu)
Modified Mon Jun 23 14:09:52 1997 by aeb - add EINTR.
Modified Tue Jul  7 12:26:42 1998 by aeb - changed return value wait3
Modified 2004-11-11, Michael Kerrisk <mtk-manpages@gmx.net>
Rewrote much of this page, and removed much duplicated text,
replacing with pointers to wait.2

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