kaka
apue笔记
apue代码编译http://blog.163.com/casillas_yeah/blog/static/1041019820103505716852/
fork函数
#include<unistd.h>
pid_t fork(void)
返回值:子进程中返回0,父进程中返回子进程ID,出错返回1
子进程获得父进程的数据空间,堆,和栈的副本,注意这是子进程所拥有的副本,父子进程并不共享存储空间,只共享正文段
#include<unistd.h> #include<sys/types.h> char buf[] = "a write to stdout\n"; int glob = 6; int main(void) { int var; pid_t pid; var = 88; if(write(STDOUT_FILENO,buf,sizeof(buf)-1) != sizeof(buf) - 1) printf("write error"); printf("before fork\n"); if((pid = fork()) < 0)printf("error"); else if(pid == 0) { glob++; var++; printf("this is child process pid = %d\n",getpid()); printf("this is child process my parentprocess pid = %d\n",getppid()); } else { printf("this is parentprocess pid = %d\n",getpid()); sleep(2); } printf("pid = %d,processpid = %d,glob = %d,var = %d\n",pid,getpid(),glob,var); exit(0); }
输出
xiaobo@xiaobo-desktop:~/桌面/apue/myapue$ ./a.out
a write to stdout
before fork
pid = 2319,glob = 7,var = 89
pid = 2318,glob = 6,var = 88
xiaobo@xiaobo-desktop:~/桌面/apue/myapue$ ./a.out > temp.out
xiaobo@xiaobo-desktop:~/桌面/apue/myapue$ cat temp.out
a write to stdout
before fork
pid = 2323,glob = 7,var = 89
before fork
pid = 2322,glob = 6,var = 88
vfock函数