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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  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 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
   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

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

COLOPHON

   This page is part of release 4.09 of the Linux  man-pages  project.   A
   description  of  the project, information about reporting bugs, and the
   latest    version    of    this    page,    can     be     found     at
   https://www.kernel.org/doc/man-pages/.



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