wait4(2) - f31

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 *wstatus, int options,
15                   struct rusage *rusage);
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17       pid_t wait4(pid_t pid, int *wstatus, 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():
23           Since glibc 2.19:
24               _DEFAULT_SOURCE || _XOPEN_SOURCE >= 500
25           Glibc 2.19 and earlier:
26               _BSD_SOURCE || _XOPEN_SOURCE >= 500
27       wait4():
28           Since glibc 2.19:
29               _DEFAULT_SOURCE
30           Glibc 2.19 and earlier:
31               _BSD_SOURCE
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DESCRIPTION

34       These functions are nonstandard; in new programs, the use of waitpid(2)
35       or waitid(2) is preferable.
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37       The wait3() and wait4() system calls are  similar  to  waitpid(2),  but
38       additionally  return  resource usage information about the child in the
39       structure pointed to by rusage.
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41       Other than the use of the rusage argument, the following wait3() call:
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43           wait3(wstatus, options, rusage);
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45       is equivalent to:
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47           waitpid(-1, wstatus, options);
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49       Similarly, the following wait4() call:
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51           wait4(pid, wstatus, options, rusage);
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53       is equivalent to:
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55           waitpid(pid, wstatus, options);
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57       In other words, wait3() waits of any child, while wait4() can  be  used
58       to select a specific child, or children, on which to wait.  See wait(2)
59       for further details.
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61       If rusage is not NULL, the struct rusage to which  it  points  will  be
62       filled  with  accounting information about the child.  See getrusage(2)
63       for details.
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RETURN VALUE

66       As for waitpid(2).
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ERRORS

69       As for waitpid(2).
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CONFORMING TO

72       4.3BSD.
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74       SUSv1 included a specification of wait3(); SUSv2 included wait3(),  but
75       marked it LEGACY; SUSv3 removed it.
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NOTES

78       Including <sys/time.h> is not required these days, but increases porta‐
79       bility.  (Indeed, <sys/resource.h> defines the  rusage  structure  with
80       fields of type struct timeval defined in <sys/time.h>.)
81
82   C library/kernel differences
83       On  Linux,  wait3()  is  a  library  function implemented on top of the
84       wait4() system call.
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COLOPHON

90       This page is part of release 5.02 of the Linux  man-pages  project.   A
91       description  of  the project, information about reporting bugs, and the
92       latest    version    of    this    page,    can     be     found     at
93       https://www.kernel.org/doc/man-pages/.
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97Linux                             2018-04-30                          WAIT4(2)