1WAIT4(2) Linux Programmer's Manual WAIT4(2)
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6 wait3, wait4 - wait for process to change state, BSD style
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9 #include <sys/wait.h>
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11 pid_t wait3(int *wstatus, int options, struct rusage *rusage);
12 pid_t wait4(pid_t pid, int *wstatus, int options,
13 struct rusage *rusage);
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15 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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17 wait3():
18 Since glibc 2.26:
19 _DEFAULT_SOURCE
20 || (_XOPEN_SOURCE >= 500 &&
21 ! (_POSIX_C_SOURCE >= 200112L
22 || _XOPEN_SOURCE >= 600))
23 From glibc 2.19 to 2.25:
24 _DEFAULT_SOURCE || _XOPEN_SOURCE >= 500
25 Glibc 2.19 and earlier:
26 _BSD_SOURCE || _XOPEN_SOURCE >= 500
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28 wait4():
29 Since glibc 2.19:
30 _DEFAULT_SOURCE
31 Glibc 2.19 and earlier:
32 _BSD_SOURCE
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35 These functions are nonstandard; in new programs, the use of waitpid(2)
36 or waitid(2) is preferable.
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38 The wait3() and wait4() system calls are similar to waitpid(2), but ad‐
39 ditionally return resource usage information about the child in the
40 structure pointed to by rusage.
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42 Other than the use of the rusage argument, the following wait3() call:
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44 wait3(wstatus, options, rusage);
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46 is equivalent to:
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48 waitpid(-1, wstatus, options);
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50 Similarly, the following wait4() call:
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52 wait4(pid, wstatus, options, rusage);
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54 is equivalent to:
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56 waitpid(pid, wstatus, options);
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58 In other words, wait3() waits of any child, while wait4() can be used
59 to select a specific child, or children, on which to wait. See wait(2)
60 for further details.
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62 If rusage is not NULL, the struct rusage to which it points will be
63 filled with accounting information about the child. See getrusage(2)
64 for details.
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67 As for waitpid(2).
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70 As for waitpid(2).
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73 4.3BSD.
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75 SUSv1 included a specification of wait3(); SUSv2 included wait3(), but
76 marked it LEGACY; SUSv3 removed it.
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79 Including <sys/time.h> is not required these days, but increases porta‐
80 bility. (Indeed, <sys/resource.h> defines the rusage structure with
81 fields of type struct timeval defined in <sys/time.h>.)
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83 C library/kernel differences
84 On Linux, wait3() is a library function implemented on top of the
85 wait4() system call.
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88 fork(2), getrusage(2), sigaction(2), signal(2), wait(2), signal(7)
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91 This page is part of release 5.13 of the Linux man-pages project. A
92 description of the project, information about reporting bugs, and the
93 latest version of this page, can be found at
94 https://www.kernel.org/doc/man-pages/.
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98Linux 2021-03-22 WAIT4(2)