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#include<unistd.h> #include<sys/types.h> #include<pwd.h> #include<stdio.h> int main(int argc,char **argv) { pid_t my_pid,parent_pid; pid_t te ; my_pid=getpid(); parent_pid=getppid(); printf("mypid is [%d]\t parentid is [%d]\n",my_pid,parent_pid); te = fork(); printf("*********begin*************\n"); my_pid=getpid(); parent_pid=getppid(); printf("mypid is [%d]\t parentid is [%d]\t te is %d\n",my_pid,parent_pid,te); printf("*********end*************\n"); #if 0 te = fork(); my_pid=getpid(); parent_pid=getppid(); printf("mypid is [%d]\t parentid is [%d]\t te is %d\n",my_pid,parent_pid,te); getchar(); #endif
RESULT：
mypid is [1705] parentid is [1521]
*********begin*************
mypid is [1705] parentid is [1521] te is 1706
*********end*************
root@ubuntu:/usr/lsrcc/tempUserFun# *********begin*************
mypid is [1706] parentid is [1] te is 0
*********end*************
结果分析：调用fork一次，fork返回2次，一个是父进程，一个是子进程。
#include<unistd.h> #include<sys/types.h> #include<pwd.h> #include<stdio.h> int main(int argc,char **argv) { pid_t my_pid,parent_pid; pid_t te ; my_pid=getpid(); parent_pid=getppid(); printf("mypid is [%d]\t parentid is [%d]\n",my_pid,parent_pid); te = fork(); printf("*********begin*************\n"); my_pid=getpid(); parent_pid=getppid(); printf("mypid is [%d]\t parentid is [%d]\t te is %d\n",my_pid,parent_pid,te); printf("*********end*************\n"); #if 1 printf("*********2THbegin*************\n"); te = fork(); my_pid=getpid(); parent_pid=getppid(); printf("mypid is [%d]\t parentid is [%d]\t te is %d\n",my_pid,parent_pid,te); printf("********2TH*end*************\n"); getchar(); #endif }
RESULT：
*********begin*************
mypid is [1801] parentid is [1521] te is 1802
*********end*************//第一次fork父进程
*********2THbegin*************
mypid is [1801] parentid is [1521] te is 1803//第2次fork的父进程（在第一次fork的父进程基础上）
********2TH*end*************
mypid is [1803] parentid is [1801] te is 0//第2次fork的子进程（在第一次fork的父进程基础上）
********2TH*end*************
*********begin*************
mypid is [1802] parentid is [1801] te is 0
*********end*************//第1次fork的子进程
*********2THbegin*************
mypid is [1802] parentid is [1801] te is 1804//第2次fork的父进程（在第2次fork的父进程基础上）
********2TH*end*************
mypid is [1804] parentid is [1802] te is 0//第2次fork的子进程（在第2次fork的父进程基础上）
********2TH*end*************
系统运行结束后有6个进程。
#include<unistd.h> #include<sys/types.h> #include<pwd.h> #include<stdio.h> int main(int argc,char **argv) { pid_t my_pid,parent_pid; pid_t te ; static int count = 0; my_pid=getpid(); parent_pid = getppid(); int i = 0; const char *p = "/usr/lsrcc/dMF/main"; for(i = 0;i < 2;++i){ te = fork(); if(te < 0){ printf("fork err!\n"); return -1; } if(te > 0){ printf("i is %i \nmypid is [%d]\t parentid is [%d]\t te is %d\n",i,my_pid,parent_pid,te); printf("this is PARENT\n"); count++; } else if(0 == te){ printf("i is %i\nmypid is [%d]\t parentid is [%d]\t te is %d\n",i,my_pid,parent_pid,te); printf("this is CHILD\n"); count++; execlp(p,NULL); } } printf("count is %d\n",count); }
RESULT:
i is 0
mypid is [2798] parentid is [2361] te is 2799
this is PARENT
i is 1
mypid is [2798] parentid is [2361] te is 2800
this is PARENT
count is 2
root@ubuntu:/usr/lsrcc/tempUserFun# i is 1
i is 0
mypid is [2798] parentid is [2361] te is 0
this is CHILD
This is mytool1 print hello
mypid is [2798] parentid is [2361] te is 0
this is CHILD
This is mytool1 print hello
This is mytool2 print hello
This is mytool2 print hello
//主要提供一个子进程调用的例子
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原文地址：http://www.cnblogs.com/ashen/p/4493416.html
