Final answer:
A program is written in C where a parent process sends two signals to a child process, which catches them and prints a message for each before terminating. The use of fork() to create a child process, and signal() along with kill() to handle and send signals respectively, demonstrates inter-process communication.
Step-by-step explanation:
Writing a C program where a parent process sends two signals to a child process involves using system calls like fork(), signal(), and kill(). The child process needs to set up signal handlers for the signals it's expected to receive. When the parent process sends these signals using kill(), the specified handler function in the child process will execute, printing a message indicating the reception of the signal before exiting.
Example C Program:
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/types.h>
#include <unistd.h>
void signal_handler(int sig) {
printf("Child process received signal %d\\", sig);
exit(0); // Terminate child process
}
int main() {
pid_t pid = fork();
if (pid == 0) { // Child process
signal(SIGUSR1, signal_handler);
signal(SIGUSR2, signal_handler);
while(1); // Wait for signals
} else if (pid > 0) { // Parent process
sleep(1); // Ensure child is ready for signals
kill(pid, SIGUSR1);
kill(pid, SIGUSR2);
} else {
perror("fork"); // Fork failed
exit(1);
}
return 0;
}
In this example, the child process sets up handlers for two user-defined signals, SIGUSR1 and SIGUSR2, and continuously loops until it receives these signals. The parent process sends these two signals to the child process, one after the other, resulting in the child process printing out the message and then terminating.