🦄 refactor(C13, C14, C115): 更新了linux系统开发部分的结构

C14-文件系统/atexit.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+static void f1(void)
+{
+    puts("f1() is working!");
+}
+
+static void f2(void)
+{
+    puts("f2() is working!");
+}
+
+static void f3(void)
+{
+    puts("f3() is working!");
+}
+
+int main(int argc, char **argv)
+{
+    puts("Begin!");
+
+    atexit(f1);
+    atexit(f2);
+    atexit(f3);
+
+    puts("End!");
+
+    exit(0);
+}
+// out:
+// *[main][~/Linux-C-Notes/C13-Linux系统编程/fs]$ ./atexit
+// Begin!
+// End!
+// f3() is working!
+// f2() is working!
+// f1() is working!