wait4(2) - Linux manual page (original) (raw)
wait4(2) System Calls Manual wait4(2)
NAME top
wait3, wait4 - wait for process to change state, BSD styleLIBRARY top
Standard C library (_libc_, _-lc_)SYNOPSIS top
**#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_SOURCEDESCRIPTION top
These functions are nonstandard; in new programs, the use of
[waitpid(2)](../man2/waitpid.2.html) or [waitid(2)](../man2/waitid.2.html) is preferable.
The **wait3**() and **wait4**() system calls are similar to [waitpid(2)](../man2/waitpid.2.html),
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)](../man2/wait.2.html) 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)](../man2/getrusage.2.html) for details.RETURN VALUE top
As for [waitpid(2)](../man2/waitpid.2.html).ERRORS top
As for [waitpid(2)](../man2/waitpid.2.html).STANDARDS top
None.HISTORY top
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.
SEE ALSO top
[fork(2)](../man2/fork.2.html), [getrusage(2)](../man2/getrusage.2.html), [sigaction(2)](../man2/sigaction.2.html), [signal(2)](../man2/signal.2.html), [wait(2)](../man2/wait.2.html), [signal(7)](../man7/signal.7.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.10 2024-07-23 wait4(2)
Pages that refer to this page:time(1), _exit(2), getrusage(2), syscalls(2), wait(2), popen(3), signal(7)