Msc computer science sem -1 | Advance operating System sppu practical slip with answers

 SAVITIBAI PHULE UNIVERSITY M.Sc.(Computer Science) Sem-I Practical Examination (From 2023-2024) SUBJECT: CS-504-MJP: Lab Course on CS-501-MJ (Advanced Operating System)  Answers is here -

Time: 3 Hours Max. Marks: 35

 ____________________________________________________________________ 


-------------------------- Slip 10 -------------------- 


Q.1) Write a program that illustrates how to execute two commands concurrently with a pipe. [10 Marks ]


#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>


int main() {

    int pipe_fd[2];

    pid_t child_pid;


    // Create a pipe

    if (pipe(pipe_fd) == -1) {

        perror("Pipe creation failed");

        exit(EXIT_FAILURE);

    }


    // Create a child process

    if ((child_pid = fork()) == -1) {

        perror("Fork failed");

        exit(EXIT_FAILURE);

    }


    if (child_pid == 0) {  // Child process

        // Close the write end of the pipe

        close(pipe_fd[1]);


        // Redirect standard input to read from the pipe

        dup2(pipe_fd[0], STDIN_FILENO);


        // Close the unused end of the pipe

        close(pipe_fd[0]);


        // Execute the second command (e.g., 'wc -w' as an example)

        execlp("wc", "wc", "-w", NULL);


        // If execlp fails

        perror("execlp failed");

        exit(EXIT_FAILURE);

    } else {  // Parent process

        // Close the read end of the pipe

        close(pipe_fd[0]);


        // Redirect standard output to write to the pipe

        dup2(pipe_fd[1], STDOUT_FILENO);


        // Close the unused end of the pipe

        close(pipe_fd[1]);


        // Execute the first command (e.g., 'ls' as an example)

        execlp("ls", "ls", NULL);


        // If execlp fails

        perror("execlp failed");

        exit(EXIT_FAILURE);

    }


    // To run this program on a Linux machine, compile it using a C compiler (e.g., gcc):

    // gcc concurrent_commands.c -o concurrent_commands


    // Then, execute the compiled program:

    // ./concurrent_commands


    return 0;

}




 Q.2) Generate parent process to write unnamed pipe and will write into it. Also generate child process which will read from pipe



#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>


#define BUFFER_SIZE 256


int main() {

    int pipe_fd[2];

    pid_t child_pid;


    // Create a pipe

    if (pipe(pipe_fd) == -1) {

        perror("Pipe creation failed");

        exit(EXIT_FAILURE);

    }


    // Create a child process

    if ((child_pid = fork()) == -1) {

        perror("Fork failed");

        exit(EXIT_FAILURE);

    }


    if (child_pid == 0) {  // Child process

        // Close the write end of the pipe

        close(pipe_fd[1]);


        char buffer[BUFFER_SIZE];

        ssize_t read_bytes;


        // Read from the pipe and print the received data

        printf("Child process reading from the pipe:\n");

        while ((read_bytes = read(pipe_fd[0], buffer, BUFFER_SIZE)) > 0) {

            write(STDOUT_FILENO, buffer, read_bytes);

        }


        if (read_bytes == -1) {

            perror("Read from pipe failed");

            exit(EXIT_FAILURE);

        }


        // Close the read end of the pipe

        close(pipe_fd[0]);

    } else {  // Parent process

        // Close the read end of the pipe

        close(pipe_fd[0]);


        // Data to be written into the pipe

        const char *message = "Hello, Child!";


        // Write data into the pipe

        write(pipe_fd[1], message, strlen(message));


        // Close the write end of the pipe

        close(pipe_fd[1]);


        // Wait for the child process to complete

        wait(NULL);

    }


    return 0;

}


gcc parent_child_pipe.c -o parent_child_pipe
./parent_child_pipe




******************************************************


Slip No 13

Q1 . Write a C program that illustrates suspending and resuming processes using signals

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

volatile sig_atomic_t child_suspended = 0;

// Signal handler for the SIGUSR1 signal (suspend)
void suspend_handler(int signum) {
    (void) signum;
    child_suspended = 1;
    printf("Child process suspended.\n");
}

// Signal handler for the SIGUSR2 signal (resume)
void resume_handler(int signum) {
    (void) signum;
    child_suspended = 0;
    printf("Child process resumed.\n");
}

int main() {
    pid_t child_pid;

    // Set up signal handlers
    signal(SIGUSR1, suspend_handler);
    signal(SIGUSR2, resume_handler);

    // Create a child process
    if ((child_pid = fork()) == -1) {
        perror("Fork failed");
        exit(EXIT_FAILURE);
    }

    if (child_pid == 0) {  // Child process
        while (1) {
            // Child process is doing some work
            printf("Child process is working...\n");
            sleep(1);
        }
    } else {  // Parent process
        sleep(2);  // Give the child some time to start

        // Send SIGUSR1 to the child process to suspend it
        kill(child_pid, SIGUSR1);

        // Wait for a moment
        sleep(3);

        // Send SIGUSR2 to the child process to resume it
        kill(child_pid, SIGUSR2);

        // Wait for the child process to complete
        wait(NULL);
    }

    return 0;
}



Q2. Write a C program that a string as an argument and return all the files that begins with that name in the current directory. For example > ./a.out foo will return all file names that begins with foo

#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <string.h>

void listFiles(const char *prefix) {
    DIR *dir;
    struct dirent *entry;

    // Open the current directory
    if ((dir = opendir(".")) == NULL) {
        perror("Error opening directory");
        exit(EXIT_FAILURE);
    }

    // Iterate over the directory entries
    while ((entry = readdir(dir)) != NULL) {
        // Check if the entry is a regular file and starts with the given prefix
        if (entry->d_type == DT_REG && strncmp(entry->d_name, prefix, strlen(prefix)) == 0) {
            printf("%s\n", entry->d_name);
        }
    }

    // Close the directory
    closedir(dir);
}

int main(int argc, char *argv[]) {
    // Check if the correct number of arguments is provided
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <prefix>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    // Get the prefix from the command line argument
    const char *prefix = argv[1];

    // List files in the current directory with the specified prefix
    listFiles(prefix);

    return 0;
}



**************************************


Slip No 15

Q1. Display all the files from current directory whose size is greater that n Bytes Where n is accept from user


#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <sys/stat.h>

void listFilesWithSize(const char *directoryPath, long sizeThreshold) {
    DIR *dir;
    struct dirent *entry;
    struct stat fileStat;

    // Open the specified directory
    if ((dir = opendir(directoryPath)) == NULL) {
        perror("Error opening directory");
        exit(EXIT_FAILURE);
    }

    // Iterate over the directory entries
    while ((entry = readdir(dir)) != NULL) {
        // Build the full path of the file
        char filePath[PATH_MAX];
        snprintf(filePath, sizeof(filePath), "%s/%s", directoryPath, entry->d_name);

        // Get information about the file
        if (stat(filePath, &fileStat) == -1) {
            perror("Error getting file information");
            exit(EXIT_FAILURE);
        }

        // Check if the entry is a regular file and its size is greater than the threshold
        if (S_ISREG(fileStat.st_mode) && fileStat.st_size > sizeThreshold) {
            printf("%s - %ld bytes\n", entry->d_name, fileStat.st_size);
        }
    }

    // Close the directory
    closedir(dir);
}

int main() {
    long sizeThreshold;

    // Get the size threshold from the user
    printf("Enter the size threshold in bytes: ");
    scanf("%ld", &sizeThreshold);

    // List files in the current directory with size greater than the specified threshold
    listFilesWithSize(".", sizeThreshold);

    return 0;
}





Q2. Write a C program which creates a child process to run linux/ unix command or any user defined program. The parent process set the signal handler for death of child signal and Alarm signal. If a child process does not complete its execution in 5 second then parent process kills child process


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

void childHandler(int signum) {
    (void)signum;
    printf("Child process terminated.\n");
    exit(EXIT_SUCCESS);
}

void alarmHandler(int signum) {
    (void)signum;
    printf("Timeout: Child process exceeded 5 seconds. Killing...\n");
    exit(EXIT_FAILURE);
}

int main(int argc, char *argv[]) {
    pid_t child_pid;
    int status;

    // Check if a command is provided as an argument
    if (argc < 2) {
        fprintf(stderr, "Usage: %s <command> [args...]\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    // Set signal handlers
    signal(SIGCHLD, childHandler);
    signal(SIGALRM, alarmHandler);

    // Create a child process
    if ((child_pid = fork()) == -1) {
        perror("Fork failed");
        exit(EXIT_FAILURE);
    }

    if (child_pid == 0) {  // Child process
        // Execute the command provided in the arguments
        execvp(argv[1], &argv[1]);

        // If execvp fails
        perror("execvp failed");
        exit(EXIT_FAILURE);
    } else {  // Parent process
        // Set an alarm for 5 seconds
        alarm(5);

        // Wait for the child process to complete
        waitpid(child_pid, &status, 0);

        // Disable the alarm
        alarm(0);

        // Check if the child process terminated normally
        if (WIFEXITED(status)) {
            printf("Child process exited with status: %d\n", WEXITSTATUS(status));
        } else {
            printf("Child process terminated abnormally.\n");
        }
    }

    return 0;
}






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