$ \textbf{mkdir b}
$ \textbf{echo b > b/b}
$ \textbf{echo c > b/c}
$ \textbf{mkdir b/d}
$ \textbf{echo d > b/d/d}
$ \textbf{hg add b}
adding b/b
adding b/c
adding b/d/d
$ \textbf{hg commit -m 'Added all files in subdirectory'}