diff --git a/Documentation/applications/nsh/commands.rst b/Documentation/applications/nsh/commands.rst
index dc8559d4417..8e4c933db07 100644
--- a/Documentation/applications/nsh/commands.rst
+++ b/Documentation/applications/nsh/commands.rst
@@ -431,6 +431,47 @@ that in-memory, circular buffer to the NSH console output.
 ``dmesg`` has the side effect of clearing the buffered data so
 that entering ``dmesg`` again will show only newly buffered data.
 
+.. _cmddu:
+
+``du`` Estimate File Space Usage
+================================
+
+**Command Syntax**::
+
+  du [-h] [-s] [-a] [-d N] <path>...
+
+**Synopsis**. Recursively summarize the apparent size of each
+``<path>`` in 1K-blocks, or in human-readable form with ``-h``. If
+no ``<path>`` is given, the current working directory is used. As
+an example::
+
+  nsh> du
+  397449  /data/test/elf
+  71993   /data/test/coredump
+  5       /data/test/log2
+  3251    /data/test/log1
+  472700  /data/test
+  nsh> du -h
+  388.1M  /data/test/elf
+  70.3M   /data/test/coredump
+  4.1K    /data/test/log2
+  3.1M    /data/test/log1
+  461.6M  /data/test
+  nsh>
+
+**Options**
+
+========  ===========================================================
+``-s``    Summary only: print only the total for each ``<path>``.
+``-a``    List all files, not only directories.
+``-d N``  Print at most N directory depth levels.
+``-h``    Human-readable sizes (K/M/G, one decimal; ``B`` below 1K).
+========  ===========================================================
+
+Sizes are apparent sizes (``st_size``), not block usage. ``-h``
+prints one decimal using integer arithmetic and does not require
+float printf support.
+
 .. _cmdecho:
 
 ``echo`` Echo Strings and Variables