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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 *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 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.

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 porta-
     bility.  (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.