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WAIT4(2)                      Linux Programmer's Manual                      WAIT4(2)

NAME         top

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

SYNOPSIS         top

       #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);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       wait3():
           _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
       wait4():
           _BSD_SOURCE

DESCRIPTION         top

       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         top

       As for waitpid(2).

ERRORS         top

       As for waitpid(2).

CONFORMING TO         top

       4.3BSD.

NOTES         top

       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>.)

       On Linux, wait3() is a library function implemented on top of the wait4()
       system call.

SEE ALSO         top

       fork(2), getrusage(2), sigaction(2), signal(2), wait(2), signal(7)

COLOPHON         top

       This page is part of release 3.32 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/.

Linux                                 2010-09-20                             WAIT4(2)

HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface

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