Manpage of WAIT4

WAIT4

Section: Linux Programmer's Manual (2)
Updated: 2016-03-15
Index
 

NAME

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

SYNOPSIS

#include <sys/types.h>#include <sys/time.h>#include <sys/resource.h>#include <sys/wait.h>pid_t wait3(int *wstatus, int options,            struct rusage *rusage);pid_t wait4(pid_t pid, int *wstatus, int options,            struct rusage *rusage);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

wait3():
    Since glibc 2.19:
        _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  

DESCRIPTION

These functions are obsolete; use waitpid(2) or waitid(2) in new programs.

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 rusageargument, 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 rusageis not NULL, the struct rusageto which it points will be filled with accounting information about the child. See getrusage(2) for details.  

RETURN VALUE

As for waitpid(2).  

ERRORS

As for waitpid(2).  

CONFORMING TO

4.3BSD.

SUSv1 included a specification of wait3(); SUSv2 included wait3(), but marked it LEGACY; SUSv3 removed it.  

NOTES

Including <sys/time.h>is not required these days, but increases portability. (Indeed, <sys/resource.h>defines the rusagestructure with fields of type struct timevaldefined 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

fork(2), getrusage(2), sigaction(2), signal(2), wait(2), signal(7)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
NOTES
C library/kernel differences
SEE ALSO

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