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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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wait4(2) System Calls Manual wait4(2)
wait3, wait4 - wait for process to change state, BSD style
Standard C library (libc, -lc)
#include <sys/wait.h>
pid_t wait3(int *_Nullable wstatus, int options,
struct rusage *_Nullable rusage);
pid_t wait4(pid_t pid, int *_Nullable wstatus, int options,
struct rusage *_Nullable rusage);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
wait3():
Since glibc 2.26:
_DEFAULT_SOURCE
|| (_XOPEN_SOURCE >= 500 &&
! (_POSIX_C_SOURCE >= 200112L
|| _XOPEN_SOURCE >= 600))
From glibc 2.19 to glibc 2.25:
_DEFAULT_SOURCE || _XOPEN_SOURCE >= 500
glibc 2.19 and earlier:
_BSD_SOURCE || _XOPEN_SOURCE >= 500
wait4():
Since glibc 2.19:
_DEFAULT_SOURCE
glibc 2.19 and earlier:
_BSD_SOURCE
These functions are nonstandard; in new programs, the use of
waitpid(2) or waitid(2) is preferable.
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(wstatus, options, rusage);
is equivalent to:
waitpid(-1, wstatus, options);
Similarly, the following wait4() call:
wait4(pid, wstatus, options, rusage);
is equivalent to:
waitpid(pid, wstatus, 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.
As for waitpid(2).
As for waitpid(2).
None.
4.3BSD.
SUSv1 included a specification of wait3(); SUSv2 included
wait3(), but marked it LEGACY; SUSv3 removed it.
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>.)
C library/kernel differences
On Linux, wait3() is a library function implemented on top of the
wait4() system call.
fork(2), getrusage(2), sigaction(2), signal(2), wait(2),
signal(7)
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2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
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Linux man-pages 6.9.1 2024-05-02 wait4(2)
Pages that refer to this page: time(1), _exit(2), getrusage(2), syscalls(2), wait(2), popen(3), signal(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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