WAIT4(2)                                            Linux Programmer's Manual                                           WAIT4(2)



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 *status, int options,
                   struct rusage *rusage);

       pid_t wait4(pid_t pid, int *status, int options,
                   struct rusage *rusage);

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

       wait3(): _BSD_SOURCE
       wait4(): _BSD_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION
       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(status, options, rusage);

       is equivalent to:

           waitpid(-1, status, options);

       Similarly, the following wait4() call:

           wait4(pid, status, options, rusage);

       is equivalent to:

           waitpid(pid, status, 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.

RETURN VALUE
       As for waitpid(2).

ERRORS
       As for waitpid(2).

CONFORMING TO
       4.3BSD.

NOTES
       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>.)

       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)

COLOPHON
       This  page  is  part of release 3.25 of the Linux man-pages project.  A description of the project, and information about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                                                      2008-09-28                                                   WAIT4(2)