ex1 w6

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>

void sigusr1_handler(int signum) {
    FILE *file = fopen("text.txt", "r");
    if (file == NULL) {
        perror("Failed to open text.txt");
        exit(1);
    }
    char buffer[1024];
    while (fgets(buffer, sizeof(buffer), file)) {
        fputs(buffer, stdout);
    }
    fclose(file);
}

void sigusr2_handler(int signum) {
    printf("Process terminating...\n");
    exit(0);
}

int main() {
    // Create and write the PID to /var/run/agent.pid
    FILE *pid_file = fopen("/var/run/agent.pid", "w");
    if (pid_file == NULL) {
        perror("Failed to create /var/run/agent.pid");
        exit(1);
    }
    fprintf(pid_file, "%d", getpid());
    fclose(pid_file);

    // Set up signal handlers
    signal(SIGUSR1, sigusr1_handler);
    signal(SIGUSR2, sigusr2_handler);

    // Read and print the contents of text.txt
    FILE *text_file = fopen("text.txt", "r");
    if (text_file == NULL) {
        perror("Failed to open text.txt");
        exit(1);
    }
    char buffer[1024];
    while (fgets(buffer, sizeof(buffer), text_file)) {
        fputs(buffer, stdout);
    }
    fclose(text_file);

    // Sleep indefinitely
    while (1) {
        sleep(1);
    }

    return 0;
}


#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int main() {
    // Check if the agent exists by reading its PID from /var/run/agent.pid
    int pid_file = open("/var/run/agent.pid", O_RDONLY);
    if (pid_file == -1) {
        printf("Error: No agent found.\n");
        exit(1);
    }

    char pid_buffer[10];
    ssize_t bytes_read = read(pid_file, pid_buffer, sizeof(pid_buffer));
    if (bytes_read <= 0) {
        perror("Failed to read agent PID");
        exit(1);
    }
    close(pid_file);
    int agent_pid = atoi(pid_buffer);

    printf("Agent found.\n");

    while (1) {
        char choice[20];
        printf("Choose a command {\"read\", \"exit\", \"stop\", \"continue\"} to send to the agent: ");
        scanf("%s", choice);

        if (strcmp(choice, "read") == 0) {
            kill(agent_pid, SIGUSR1);
        } else if (strcmp(choice, "exit") == 0) {
            kill(agent_pid, SIGUSR2);
            exit(0);
        } else if (strcmp(choice, "stop") == 0) {
            kill(agent_pid, SIGSTOP);
        } else if (strcmp(choice, "continue") == 0) {
            kill(agent_pid, SIGCONT);
        } else {
            printf("Invalid command.\n");
        }
    }

    return 0;
}