Words To Beautiful Notes

# Fork - `fork()` is a system call used for creating a new process (child process) by duplicating the calling process (parent process). - The child process gets its own memory space and can execute a different code path from the parent process. - `fork()` returns different values to the parent and child processes: - Child pid == 0 - Parent pid > 0 - Error pid < 0 - Both the parent and child processes continue executing from the line of code immediately following the `fork()` call. However, they can distinguish themselves by checking the return value of `fork()`. # Communicating between processes ## Pipes - Pipes are a method of communication between two processes, where one process writes to a pipe and the other reads from the pipe. - In Unix-like systems, pipes are created using the `pipe()` system call. - Pipes are a one-way communication channel, so to enable two-way communication, two pipes must be used. - Pipes can be used for parent-child communications, where the child process writes to the pipe and the parent process reads from the pipe. - Example of using pipes for parent-child communication: ```c #include <stdio.h> #include <stdlib.h> #include <unistd.h> int main() { int fd[2]; pid_t pid; char buffer[20]; if (pipe(fd) < 0) { perror("pipe"); exit(EXIT_FAILURE); } pid = fork(); if (pid < 0) { perror("fork"); exit(EXIT_FAILURE); } else if (pid == 0) { // child process close(fd[0]); // close unused read end write(fd[1], "Hello, parent!", 14); close(fd[1]); // close write end } else { // parent process close(fd[1]); // close unused write end read(fd[0], buffer, sizeof(buffer)); printf("Received message: %s\n", buffer); close(fd[0]); // close read end } return 0; } ....