diff --git a/README.md b/README.md
index ca19de6..e61ebf5 100644
--- a/README.md
+++ b/README.md
@@ -4,3 +4,7 @@ Code from programming books I work through—both sample code from the books and
 I write myself.
 
 ## Advanced Programming in the UNIX environment
+
+Working through both [the book](http://www.apuebook.com) and [this online course](https://stevens.netmeister.org/631/).
+
+
diff --git a/apitue/01/ls b/apitue/01/ls
new file mode 100755
index 0000000..837c256
Binary files /dev/null and b/apitue/01/ls differ
diff --git a/apitue/01/ls.c b/apitue/01/ls.c
new file mode 100644
index 0000000..f2a7bf6
--- /dev/null
+++ b/apitue/01/ls.c
@@ -0,0 +1,27 @@
+#include <sys/types.h>
+
+#include <dirent.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv) {
+  DIR *dp;
+  struct dirent *dirp;
+
+  if (argc != 2) {
+    fprintf(stderr, "usage: %s dir_name\n", argv[0]);
+    exit(1);
+  }
+
+  if ((dp = opendir(argv[1])) == NULL) {
+    fprintf(stderr, "can't open '%s'\n", argv[1]);
+    exit(1);
+  }
+
+  while ((dirp = readdir(dp)) != NULL) {
+    printf("%s\n", dirp->d_name);
+  }
+
+  closedir(dp);
+  return(EXIT_SUCCESS);
+}
diff --git a/apitue/01/simple_cat b/apitue/01/simple_cat
new file mode 100755
index 0000000..26d7641
Binary files /dev/null and b/apitue/01/simple_cat differ
diff --git a/apitue/01/simple_cat.c b/apitue/01/simple_cat.c
new file mode 100644
index 0000000..f0865ea
--- /dev/null
+++ b/apitue/01/simple_cat.c
@@ -0,0 +1,33 @@
+// Reads from STDIN only
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#ifndef BUFFSIZE
+#define BUFFSIZE 32768
+#endif
+
+int main (int argc, char **argv) {
+  int n;
+  char buf[BUFFSIZE];
+
+  // Cast to void to silence compiler warnings
+  (void)argc;
+  (void)argv;
+
+  while ((n = read(STDIN_FILENO, buf, BUFFSIZE)) > 0) {
+    if (write(STDOUT_FILENO, buf, n) != n) {
+      fprintf(stderr, "Unable to write: %s\n", strerror(errno));
+      exit(EXIT_FAILURE);
+    }
+  }
+
+  if (n < 0) {
+    fprintf(stderr, "Unable to read: %s\n", strerror(errno));
+    exit(EXIT_FAILURE);
+  }
+
+  return EXIT_SUCCESS;
+}