diff --git a/src/user-guide/installing-workflows.rst b/src/user-guide/installing-workflows.rst
index a3464f1882..601bd5cae2 100644
--- a/src/user-guide/installing-workflows.rst
+++ b/src/user-guide/installing-workflows.rst
@@ -398,6 +398,12 @@ The run directory now looks as follows:
    │       └── <time-stamp>-reinstall.log
    └── .service
 
+.. note::
+
+   If your workflow needs to create or install scripts or executables at runtime
+   and you don't want Cylc to delete them on re-installation, you can use
+   ``bin`` and ``lib/python`` directories in the :ref:` workflow share directory <workflow_share_directories>`.
+
 
 Expected Errors
 ---------------
diff --git a/src/user-guide/writing-workflows/configuration.rst b/src/user-guide/writing-workflows/configuration.rst
index 4ce12c366a..16bbf4a39a 100644
--- a/src/user-guide/writing-workflows/configuration.rst
+++ b/src/user-guide/writing-workflows/configuration.rst
@@ -55,6 +55,12 @@ Other files and folders may be placed in the :term:`source directory` too:
 documentation, configuration files, etc. When the workflow is :ref:`installed
 <Installing-workflows>` these will be copied over to the :term:`run directory`.
 
+.. note::
+
+   If your workflow needs to create or install scripts or executables at runtime
+   and you don't want Cylc to delete them on re-installation, you can use
+   equivalent directories in the :ref:`workflow_share_directories`.
+
 
 .. _SyntaxHighlighting:
 
diff --git a/src/user-guide/writing-workflows/runtime.rst b/src/user-guide/writing-workflows/runtime.rst
index 6a6eeed2f2..a23c94b642 100644
--- a/src/user-guide/writing-workflows/runtime.rst
+++ b/src/user-guide/writing-workflows/runtime.rst
@@ -306,6 +306,8 @@ exported to subshells:
                                    #   relative to the workflow work directory
 
 
+.. _workflow_share_directories:
+
 Workflow Share Directories
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -317,6 +319,22 @@ output files are typically held in cycle point sub-directories of this.
 The top level share directory location can be changed, e.g. to a large data
 area, by global config settings under :cylc:conf:`global.cylc[install][symlink dirs]`.
 
+If your workflow creates or installs executables or Python libraries
+as it is running, these can be placed in:
+
+* ``share/bin/`` - for executables. This location is automatically added to ``PATH``
+  (before the top-level ``bin/`` in the run dir).
+* ``share/lib/python/`` - for Python modules. This location is automatically added
+  to ``PYTHONPATH`` (before the top-level ``lib/python/`` in the run dir).
+
+.. note::
+
+   Cylc will not create these folders.
+
+.. seealso::
+
+   :ref:`Top level "bin/" and "lib/python/" directories <WorkflowDefinitionDirectories>`.
+
 
 Task Work Directories
 ^^^^^^^^^^^^^^^^^^^^^