sending a string between two programs using named pipes - c

Question

I am trying to send a string to another program
but i am having problem using O_WRONLY | O_NONBLOCK,
if i replace that with O_RDWR the program works fine
but i wanted to know if there is a way to send/read the
string without using O_RDWR. Right now it returns a
empty string for some reason.
Writer:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#define MAX_LINE 1024
int main(int argc, char **argv)
{
char line[MAX_LINE];
int pipe;
printf("Enter line: \n");
fgets(line, MAX_LINE, stdin);
pipe = open("link1", O_WRONLY | O_NONBLOCK);
write(pipe, line, strlen(line));
system("./run"); //executing the reader
close(pipe);
return 0;
}
reader:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#define MAX_BUF 1024
int main(int argc, char **argv)
{
int fd;
char * link1 = "link1";
char buf[MAX_BUF];
fd = open(link1, O_RDONLY | O_NONBLOCK);
read(fd, buf, MAX_BUF);
printf("%s\n", buf);
close(fd);
return 0;
}

Answer 1

Are you running the reader first? If no process has the FIFO open for reading when the writer attempts to open it write only, then the open will fail.
From the Open Group man page:
When opening a FIFO with O_RDONLY or O_WRONLY set: If O_NONBLOCK is set:
An open() for reading only will return without delay. An open() for writing only will return an error if no process currently has the file open for reading.