System call

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <fcntl.h>

#include <sys/types.h>

#include <sys/stat.h>

int main() {

    // Open a source file for reading

    int source_fd = open("source.txt", O_RDONLY);

    if (source_fd == -1) {

        perror("Failed to open source.txt");

        exit(1);

    }

    // Create or open a destination file for writing

    int dest_fd = open("destination.txt", O_WRONLY | O_CREAT | O_TRUNC, 0644);

    if (dest_fd == -1) {

        perror("Failed to open destination.txt");

        close(source_fd);

        exit(1);

    }

    // Read from the source file and write to the destination file

    char buffer[1024];

    ssize_t nread;

    while ((nread = read(source_fd, buffer, sizeof(buffer))) > 0) {

        if (write(dest_fd, buffer, nread) != nread) {

            perror("Write error");

            close(source_fd);

            close(dest_fd);

            exit(1);

        }

    }

    // Check if there was an error during reading

    if (nread < 0) {

        perror("Read error");

    }

    // Close both files

    close(source_fd);

    close(dest_fd);

    return 0;

}