wait4() - Unix, Linux System Call

NAME

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); 

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).

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>.)

The prototype for these functions is only available if _BSD_SOURCE is defined.

CONFORMING TO

4.3BSD

SEE ALSO

• fork (2)

• getrusage (2)

• sigaction (2)

• signal (2)

• wait (2)