wait4() - Unix, Linux System Call
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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);
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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);
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is equivalent to:
waitpid(-1, status, options);
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Similarly, the following
wait4() call:
wait4(pid, status, options, rusage);
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is equivalent to:
waitpid(pid, status, options);
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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
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