Table of open flags
+o-append+
+o-async+
+o-cloexec+
+o-creat+
+o-direct+
+o-directory+
+o-excl+
+o-largefile+
+o-noatime+
+o-noctty+
+o-nofollow+
+o-nonblock+
+o-ndelay+
+o-rdonly+
+o-rdwr+
+o-sync+
+o-trunc+
+o-wronly+