1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
/*
* Recitation Section Number:
* Breakout Number:
* Member Name
* Member Name
* Member Name
* Member Name
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#define BUFSIZE 20
#define PERM 0644
int main(int argc, char *argv[]) {
int infile; char buffer[BUFSIZE];
// create/open a file named write.txt
infile = open("write.txt", O_CREAT | O_RDWR | O_TRUNC, PERM);
// write hello world to write.txtS
write(infile, "hello world\n", 12);
// spawn a child process and use this child process to reroute stdout to write.txt
pid_t pid = fork();
if (!pid) {
dup2(infile, 1);
}
// print pid
printf("Process %d\n", pid);
// use the child process spawned previously to read the contents from write.txt, restore output to stdout
// and then prints the contents of write.txt to stdout.
if (!pid) {
read(infile, buffer, 20);
int stdout = open("/dev/tty", O_WRONLY);
dup2(1, stdout);
printf("%s\n", buffer);
return 0;
}
// print pid
printf("%d\n", pid);
// close the file write.txt
close(infile);
return 0;
}
|
