wait3和wait4 Functions

提供了与wait，waitpid，waitid函数唯一不能提供的特性：增加了额外的参数，用于存放中止进程的所有资源的汇总和其所有的子进程

wait3, wait4 - wait for process to change state, BSD style

#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);
//Return: process ID if OK, -1 on error

包含了资源信息

1. the amount of user CPU time
2. the amount of system CPU time
3. number of page faults
4. number of signal received

可以man getrusage manual查看详细的额外信息

single UNIX specification 版本3已经移除了wait3