Unix IPC: Pipes and FIFOs
25 Nov 2012This snippet will show you two processes communicating between each other using a pipe.
int pfds[2];
char buf[30];
/* open the pipe */
pipe(pfds);
if (!fork()) {
/* the child will write to the pipe */
write(pfds[1], "test", 5);
exit(0);
} else {
/* the parent will read from the pipe */
read(pfds[0], buf, 5);
wait(NULL);
}FIFOs are just pipes that have a specific name. In this snippet the name is a constant defined elsewhere called FIFO_NAME.
/* first program writes to the named pipe */
char buffer[20];
int num, fd;
/* create the named pipe */
mknod(FIFO_NAME, S_IFIFO | 0666, 0);
/* open for writing */
fd = open(FIFO_NAME, O_WRONLY);
/* write to the pipe */
write(fd, buffer, strlen(buffer));
/* second program reads from the named pipe */
char buffer[20];
int num, fd;
/* create the named pipe */
mknod(FIFO_NAME, S_IFIFO | 0666, 0);
/* open for reading */
fd = open(FIFO_NAME, O_RDONLY);
/* read from the pipe */
read(fd, s, 20);