1 #include <stdio.h>
 2 #include <unistd.h>
 3 #include <sys/types.h>
 4 #include <sys/stat.h>
 5 #include <fcntl.h>
 6 #include <string.h>
 7 
 8 int main(int argc, char **argv)
 9 {
10         printf("before file redirect\n"); // 输出到屏幕
11         char buf[] = "before before\n";
12         write(1, buf, strlen(buf)); // 输出到屏幕
13 
14         int fd_stdout_bak = dup(1);
15         int fd_file = creat("file.dat", 0777);
16         int fd = dup2(fd_file, 1); // 1 指向 file.dat
17         printf("after file redirect, %s - %s\n", argv[0], argv[1]); // 输出到文件 file.dat
18         char buf1[] = "after after\n";
19         write(1, buf1, strlen(buf1)); // 输出到文件 file.dat
20 
21         dup2(fd_stdout_bak, 1);
22         printf("after restore stdout file\n"); // 恢复输出到屏幕
23         char buf2[] = "restore restore\n";
24         write(1, buf2, strlen(buf2)); // 恢复输出到屏幕
25 
26         close(fd_stdout_bak);
27         close(fd_file);
28 
29         return 0;
30 }