Inter Process Communication using Pipes

In this tutorial, we will investigate pipe call to understand inter-process communication. In pipe call, the child process is to be a different program from its parent, not a process running the same program.

Hence, we are developing two programs to understand how they work. Here, the first program, main_process.c, is data producer, and the second program, child_process.c, is data consumer.

Source code of main_process.c

#include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <string.h> int main() { int data_len; int f_pipes[2]; const char data[] = "987"; char buffer[BUFSIZ + 1]; pid_t fork_status; memset(buffer, '\0', sizeof(buffer)); if (pipe(f_pipes) == 0) { fork_status = fork(); if (fork_status == (pid_t)-1) { fprintf(stderr, "Fork failure"); exit(EXIT_FAILURE); } if (fork_status == 0) { sprintf(buffer, "%d", f_pipes[0]); (void)execl("child_process", "child_process", buffer, (char *)0); exit(EXIT_FAILURE); } else { data_len = write(f_pipes[1], data, strlen(data)); printf("%d - wrote %d bytes\n", getpid(), data_len); } } exit(EXIT_SUCCESS); }

Source code of child_process.c

#include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <string.h> int main(int argc, char *argv[]) { int data_len; char buffer[BUFSIZ + 1]; int f_descriptor; memset(buffer, '\0', sizeof(buffer)); sscanf(argv[1], "%d", &f_descriptor); data_len = read(f_descriptor, buffer, BUFSIZ); printf("%d - read %d bytes: %s\n", getpid(), data_len, buffer); exit(EXIT_SUCCESS); }

Happy Exploring!