【getpid/getppid系统调用】
功能描述：
getpid返回当前进程标识，getppid返回父进程标识。
用法：
#include <sys/types.h>
#include <unistd.h>
pid_t getpid(void);
pid_t getppid(void);
例子：
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
int main(void)
{
pid_t pid;
printf("Before fork ...n");
switch(pid = fork()) {
case -1:
printf("Fock call failn");
exit(1);
case 0:
printf("The pid of child is: %dn", getpid());
printf("The pid of child's parent is: %dn", getppid());
printf("Child exiting...n");
exit(0);
default:
printf("The pid of parent is: %dn", getpid());
printf("the pid of parent's child is: %dn", pid);
}
printf("After fork, program exiting...n");
exit(0);
}
getpid() getppid()进程和父进程函数
getpid()和getppid()进程和父进程函数，在调用中都不能返回错误，下面的程序输出了他的进程ID和父进程ID，由于不能保证pid_t 能够放进 int类型中去，返回值被转为long 整型输出
main()
{
#include <stdio.h>
#include <unistd.h>
printf ("I am process %ld",(long)getpid());
printf ("My parent is %ld",(long)getppid());
exit(0);
}