wait4(2) — Linux manual pages

wait4
Prev	Section 2	Next

Name

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

Synopsis

#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)`;

Note

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
`wait3`():
`_BSD_SOURCE`
`wait4`():
`_BSD_SOURCE` \|\| `_XOPEN_SOURCE` >= 500

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>

COLOPHON

This page is part of release 2.79 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

Copyright (c) 1993 by Thomas Koenig (ig25rz.uni-karlsruhe.de)
and Copyright (c) 2004 by Michael Kerrisk (mtk.manpagesgmail.com)

Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date.  The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein.  The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
professionally.

Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.
License.

Modified Sat Jul 24 13:32:44 1993 by Rik Faith (faithcs.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.manpagesgmail.com>
Rewrote much of this page, and removed much duplicated text,
replacing with pointers to wait.2