wait() and waitpid()wait(): Suspends the calling process until one of its child processes terminates. It returns the PID of the terminated child or -1 if an error occurs.waitpid(): Similar to wait(), but provides more control. It can wait for a specific child process or modify its behavior using options.wait(int *status): Waits for any child process to terminate and stores its exit status.waitpid(pid_t pid, int *status, int options): Waits for a specific child process (pid) to terminate. You can specify:
pid > 0: Wait for the specific child.pid = -1: Wait for any child (same as wait()).options: Special flags (e.g., WNOHANG to return immediately if no child has exited).#include <stdio.h>
#include <sys/wait.h>
#include <unistd.h>
int main() {
pid_t child_pid = fork();
if (child_pid == 0) {
// Child process
printf("Child process with PID: %d\n", getpid());
return 42; // Exit with status 42
} else {
// Parent process
int status;
waitpid(child_pid, &status, 0); // Wait for the child process to terminate
if (WIFEXITED(status)) {
printf("Child exited with status: %d\n", WEXITSTATUS(status));
}
}
return 0;
}
wait(): Waits for any child, returns when one exits.waitpid(): Wait for a specific child (or any child if pid=-1) with optional flags for finer control.