📝 Added sandbox (code sketchbook)

sandbox/dup2.c

@@ -0,0 +1,28 @@
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <fcntl.h>
+
+int main() {
+    int file_desc = open("dup2.txt", O_WRONLY | O_APPEND);
+
+    /* here the newfd is the file descriptor of stdout
+     * note that using our dup.c program would create a new file descriptor,
+     * dup() doesn't do that, it takes a second argument through which it will
+     * duplicate the file descriptor of whichever one we wish */
+
+    dup2(file_desc, 1);
+
+    printf("I will be printed to the file dup2.txt\n");
+
+    return 0;
+}
+
+/* https://stackoverflow.com/questions/4171126/what-do-the-dup-and-dup2-systems-really-do */
+/* EXPLANATION FROM STACKOVERFLOW:
+Both make a new file descriptor corresponding to an existing open file description.
+Most properties between the old and new fd (like position) are shared; the only property
+I can think of that's not shared is the close-on-exec flag. The difference between dup and
+dup2 is that dup assigns the lowest available file descriptor number, while dup2 lets you
+choose the file descriptor number that will be assigned and atomically closes and replaces
+it if it's already taken. */