#include
#include
#include
int main(void)
{
#define STDOUT 1 //标准输出文件描述符 号
int nul, oldstdout;
char msg[] = "This is a test";
/* create a file */
//打开一个文件，操作者具有读写权限 如果文件不存在就创建
nul = open("DUMMY.FIL", O_CREAT | O_RDWR,
S_IREAD | S_IWRITE);
/* create a duplicate handle for standard
output */
//创建STDOUT的描述符备份
oldstdout = dup(STDOUT);
/*
redirect standard output to DUMMY.FIL
by duplicating the file handle onto the
file handle for standard output.
*/
//重定向nul到STDOUT
dup2(nul, STDOUT);
/* close the handle for DUMMY.FIL */
//重定向之后要关闭nul
close(nul);
/* will be redirected into DUMMY.FIL */
//写入数据
write(STDOUT, msg, strlen(msg));
/* restore original standard output
handle */
//还原
dup2(oldstdout, STDOUT);
/* close duplicate handle for STDOUT */
close(oldstdout);
return 0;
}
//结果就是msg写到了文件中而不是STDOUT