8.8. wait3 and wait4 Functions
Most UNIX system implementations provide two additional functions: wait3 and wait4. Historically, these two variants descend from the BSD branch of the UNIX System. The only feature provided by these two functions that isn't provided by the wait, waitid, and waitpid functions is an additional argument that allows the kernel to return a summary of the resources used by the terminated process and all its child processes.
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/resource.h>
pid_t wait3(int *statloc, int options, struct
 rusage *rusage);
pid_t wait4(pid_t pid, int *statloc, int options,
struct rusage *rusage);
| Both return: process ID if OK, 0, or 1 on error |
The resource information includes such statistics as the amount of user CPU time, the amount of system CPU time, number of page faults, number of signals received, and the like. Refer to the geTRusage(2) manual page for additional details. (This resource information differs from the resource limits we described in Section 7.11.) Figure 8.11 details the various arguments supported by the wait functions.
Figure 8.11. Arguments supported by wait functions on various systemsFunction | pid | options | rusage | POSIX.1 | Free BSD 5.2.1 | Linux 2.4.22 | Mac OSX 10.3 | Solaris 9 |
|---|
wait | | | | • | • | • | • | • | waitid | • | • | | XSI | | | | • | waitpid | • | • | | • | • | • | • | • | wait3 | | • | • | | • | • | • | • | wait4 | • | • | • | | • | • | • | • |
The wait3 function was included in earlier versions of the Single UNIX Specification. In Version 2, wait3 was moved to the legacy category; wait3 was removed from the specification in Version 3.
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