Description
Inter-process Communication – Pipes
C Program with pipe IPC
Demonstrate each of the following steps to get a grade on this part of the lab assignment
- Compile and run the following program
/*Sample C program for Lab assignment 3*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
//main
int main() {
int fds[2];
pipe(fds);
/*child 1 duplicates downstream into stdin */
if (fork() == 0) {
dup2(fds[0], 0);
close(fds[1]);
execlp(“sort”, “sort”, 0);
}
/*child 2 duplicates upstream into stdout */
else if (fork() == 0) {
dup2(fds[1], 1);
close(fds[0]);
execlp(“ls”, “ls”, 0);
}
else { /*parent closes both ends and wait for children*/
close(fds[0]);
close(fds[1]);
wait(0);
wait(0);
}
return 0;
}
- Compile and run the following program
/*Sample C program for Lab assignment 3*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
// main
int main(int argc,char *argv[]){
int fds[2];
char buff[60];
int count;
int i;
pipe(fds);
if (fork()==0){
printf(“\nWriter on the upstream end of the pipe -> %d arguments \n”,argc);
close(fds[0]);
for(i=0;i<argc;i++){
write(fds[1],argv[i],strlen(argv[i]));
}
exit(0);
}
else if(fork()==0){
printf(“\nReader on the downstream end of the pipe \n”);
close(fds[1]);
while((count=read(fds[0],buff,60))>0){
for(i=0;i<count;i++){
write(1,buff+i,1);
write(1,” “,1);
}
printf(“\n”);
}
exit(0);
}
else{
close(fds[0]);
close(fds[1]);
wait(0);
wait(0);
}
return 0;
}
- Modify the program in Step 2. so that the writer process passes the output of “ls” command to the upstream end of the pipe. You may use dup2(fds[1],1); for redirection and execlp(“ls”, “ls”, 0); to run the “ls” command.
- Write a C program that implements the shell command: cat /etc/passwd | grep root
Producer – consumer with pipes
- In Computer Science, the producer–consumer problem is a classic multi- process synchronization example. The producer and the consumer share a common fixed-size buffer. The producer puts messages to the buffer while the consumer removes messages from the buffer. Pipes provide a perfect solution to this problem because of their built-in synchronization capability. So as a programmer, you do not have to worry about whether or not the buffer is empty or full to produce or consume messages.
Write a C program to implement the producer-consumer message communication using pipes.
