README and fd: start a note to tell what I'm doing here ...

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

fd.cpp

@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+int main() {
+    // Open a file for reading and writing
+    int fd = open("example.txt", O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
+    // int fd = 2; // jam in STDERR_FILENO ...
+    if (fd == -1) {
+        perror("Error opening file");
+        return EXIT_FAILURE;
+    }
+
+    // Write to the file
+    const char *text = "Hello, file descriptors!";
+    ssize_t bytes_written = write(fd, text, strlen(text));
+    if (bytes_written == -1) {
+        perror("Error writing to file");
+        close(fd);
+        return EXIT_FAILURE;
+    }
+
+    // Move the file offset to the beginning
+    if (lseek(fd, 0, SEEK_SET) == -1) {
+        perror("Error seeking in file");
+        close(fd);
+        return EXIT_FAILURE;
+    }
+
+    // Read from the file
+    char buffer[256];
+    ssize_t bytes_read = read(fd, buffer, sizeof(buffer) - 1);
+    if (bytes_read == -1) {
+        perror("Error reading from file");
+        close(fd);
+        return EXIT_FAILURE;
+    }
+
+    // Null-terminate the buffer and print the content
+    buffer[bytes_read] = '\0';
+    printf("File content: %s\n", buffer);
+
+    // Close the file
+    if (close(fd) == -1) {
+        perror("Error closing file");
+        return EXIT_FAILURE;
+    }
+
+    return EXIT_SUCCESS;
+}