wait4(2)

1WAIT4(2)                   Linux Programmer's Manual                  WAIT4(2)
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NAME

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

9       #include <sys/types.h>
10       #include <sys/time.h>
11       #include <sys/resource.h>
12       #include <sys/wait.h>
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14       pid_t wait3(int *status, int options,
15                   struct rusage *rusage);
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17       pid_t wait4(pid_t pid, int *status, int options,
18                   struct rusage *rusage);
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20   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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22       wait3(): _BSD_SOURCE
23       wait4(): _BSD_SOURCE || _XOPEN_SOURCE >= 500
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DESCRIPTION

26       The  wait3()  and  wait4()  system calls are similar to waitpid(2), but
27       additionally return resource usage information about the child  in  the
28       structure pointed to by rusage.
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30       Other than the use of the rusage argument, the following wait3() call:
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32           wait3(status, options, rusage);
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34       is equivalent to:
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36           waitpid(-1, status, options);
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38       Similarly, the following wait4() call:
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40           wait4(pid, status, options, rusage);
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42       is equivalent to:
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44           waitpid(pid, status, options);
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46       In  other  words, wait3() waits of any child, while wait4() can be used
47       to select a specific child, or children, on which to wait.  See wait(2)
48       for further details.
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50       If  rusage  is  not  NULL, the struct rusage to which it points will be
51       filled with accounting information about the child.   See  getrusage(2)
52       for details.
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RETURN VALUE

55       As for waitpid(2).
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ERRORS

58       As for waitpid(2).
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CONFORMING TO

61       4.3BSD.
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NOTES

64       Including <sys/time.h> is not required these days, but increases porta‐
65       bility.  (Indeed, <sys/resource.h> defines the  rusage  structure  with
66       fields of type struct timeval defined in <sys/time.h>.)
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68       On  Linux,  wait3()  is  a  library  function implemented on top of the
69       wait4() system call.
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COLOPHON

75       This page is part of release 3.22 of the Linux  man-pages  project.   A
76       description  of  the project, and information about reporting bugs, can
77       be found at http://www.kernel.org/doc/man-pages/.
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81Linux                             2008-09-28                          WAIT4(2)