*SYSTEM CALLS PROGRAMS*

Write()

#include<unistd.h>

int main()

{

	write(1,”Hello”,5)

}

read()

#include<unistd.h>

int main()

{

Char b[30];

read(0,b,10);

write(1,b,10);

}

Open 

#include <stdio.h>

#include <fcntl.h>

#include <unistd.h>

int main() {

    int fd;

    char *filename = "example.txt";

    

    // Open the file for reading and writing, create if it doesn't exist

    fd = open(filename, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);

    printf("File opened successfully!\n");

    

    // Close the file

    close(fd);

    printf("File closed successfully!\n");

    

    return 0;

}

lseek

#include <stdio.h>

#include <fcntl.h>

#include <unistd.h>

int main() {

    int fd;

    off_t offset;

    // Open the file for reading

    fd = open("example.txt", O_RDONLY);

    

    // Move the file offset to a specific position (e.g., 100 bytes from the beginning)

    offset = lseek(fd, 100, SEEK_SET);

    

    // Close the file

    close(fd);

    

    return 0;

}

stat. This information includes details such as file size, permissions, inode number, timestamps, and more.

#include <stdio.h>

#include <sys/stat.h>

int main() {

    const char *filename = "example.txt";

    struct stat file_stat;

    // Call the stat system call to retrieve information about the file

    stat(filename, &file_stat);

    // Display file information

    printf("File Size: %ld bytes\n", file_stat.st_size);

    printf("File Permissions: %o\n", file_stat.st_mode & 0777);

    printf("Inode Number: %ld\n", file_stat.st_ino);

    return 0;

}

Open the current directory, Read directory entries

#include <stdio.h>

#include <dirent.h>

int main() {

    DIR *dir;

    struct dirent *entry;

    // Open the current directory

    dir = opendir(".");

    if (dir == NULL) {

        perror("opendir");

        return 1;

    }

    // Read directory entries

    while ((entry = readdir(dir)) != NULL) {

        printf("%s\n", entry->d_name);

    }

    // Close the directory

    closedir(dir);

    return 0;

}