wait4
NAME
wait3, wait4 - wait for process to change state, BSD style
SYNOPSIS
#define _BSD_SOURCE
/* Or #define _XOPEN_SOURCE 500 for wait3() */
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
I pid_t wait3(int * status , int options ,
I struct rusage * rusage );
I pid_t wait4(pid_t pid , int * status , int options ,
I struct rusage * rusage );
DESCRIPTION
The
R wait3 ()
and
R wait4 ()
system calls are similar to
waitpid(2),
but additionally return resource usage information about the
child in the structure pointed to by
R rusage .
Other than the use of the
rusage
argument, the following
R wait3 ()
call:
wait3(status, options, rusage);
is equivalent to:
waitpid(-1, status, options);
Similarly, the following
R wait4 ()
call:
wait4(pid, status, options, rusage);
is equivalent to:
waitpid(pid, status, options);
In other words,
R wait3 ()
waits of any child, while
R 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
R <sys/time.h> .)
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