diff --git a/CHANGELOG.md b/CHANGELOG.md
index c816e1f..dec20fc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -33,6 +33,6 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - First working version of `dockernel install` and `dockernel start`.
 
 [unreleased]: https://github.com/mrmino/dockernel/v1.0.2...HEAD
-[1.0.1]: https://github.com/mrmino/dockernel/releases/tag/v1.0.2
+[1.0.2]: https://github.com/mrmino/dockernel/releases/tag/v1.0.2
 [1.0.1]: https://github.com/mrmino/dockernel/releases/tag/v1.0.1
 [1.0.0]: https://github.com/mrmino/dockernel/releases/tag/v1.0.0
diff --git a/README.md b/README.md
index 0cf8692..5e42067 100644
--- a/README.md
+++ b/README.md
@@ -20,17 +20,52 @@ different one.
 
 ## Usage
 
+*Note for Linux users:
+
+If you run into permission errors with `docker` or `dockernel` - either use
+`sudo`, or follow the steps outlined in [Manage Docker as a non-root
+user](https://docs.docker.com/engine/install/linux-postinstall/#manage-docker-as-a-non-root-user)
+guide.*
+
+### Creating a Dockernel image
+
 First, create a docker image that will host your kernel. This will require a
-proper dockerfile. An example can be seen
+proper dockerfile. A full example for IPython kernel can be seen
 [here](https://github.com/MrMino/dockernel/blob/master/example_dockerfile).
 
+Most kernels take a path to a "connection file" (also called "control file" by
+some kernels) as a CLI argument. This file contains all of the information
+necessary to start up a kernel, including TCP ports to use, IP address, etc.
+
+When running your container, Dockernel will supply this file and put it into a
+predefined path in the container. This path will be given via an environment
+variable visible in the container as `$DOCKERNEL_CONNECTION_FILE`.
+
+Therefore, in order for the kernel to know the connection settings it should
+use, you need to pass the contents of this variable in `CMD` of the container.
+For example, for IPython kernel:
+
+```
+CMD python -m ipykernel_launcher -f $DOCKERNEL_CONNECTION_FILE
+```
+
+Or for the Rust kernel (Evcxr, see the
+[example Rust
+dockerfile](https://github.com/MrMino/dockernel/blob/master/example_rust_dockerfile)):
+
+```
+CMD evcxr_jupyter --control_file $DOCKERNEL_CONNECTION_FILE
+```
+
 To build your image, use `docker build`. E.g. to build the example mentioned
 above:
 
 ```
-sudo docker build --tag my_kernel - < example_dockerfile
+docker build --tag my_kernel - < example_dockerfile
 ```
 
+### Installing your image as a Jupyter Kernel
+
 After that, use Dockernel to install the docker image as a Jupyter kernel:
 
 ```
diff --git a/dockernel/cli/install.py b/dockernel/cli/install.py
index 488a18e..36f6d6c 100644
--- a/dockernel/cli/install.py
+++ b/dockernel/cli/install.py
@@ -49,7 +49,7 @@ def python_argv(system_type: str) -> List[str]:
 
 def generate_kernelspec_argv(image_name: str, system_type: str) -> List[str]:
     dockernel_argv = ['dockernel', 'start',
-                     image_name, JUPYTER_CONNECTION_FILE_TEMPLATE]
+                      image_name, JUPYTER_CONNECTION_FILE_TEMPLATE]
     return python_argv(system_type) + dockernel_argv
 
 
diff --git a/dockernel/kernelspec.py b/dockernel/kernelspec.py
index 4c184b4..7016263 100644
--- a/dockernel/kernelspec.py
+++ b/dockernel/kernelspec.py
@@ -12,9 +12,12 @@
 from enum import Enum
 from pathlib import Path
 
+from .version import version as dockernel_version
+
 
 KERNELSPEC_FILENAME = 'kernel.json'
 KERNELSPEC_STORE_DIRNAME = 'kernels'
+DOCKERNEL_VERSIONFILE_FILENAME = 'DOCKERNEL'
 
 
 class InterruptMode(str, Enum):
@@ -165,3 +168,18 @@ def install_kernelspec(kernelspec_dir: Path, kernelspec: Kernelspec) -> None:
     kernelspec_dir.mkdir()
     kernelspec_file = kernelspec_dir/KERNELSPEC_FILENAME
     kernelspec_file.write_text(kernelspec.json())
+    add_dockernel_versionfile(kernelspec_dir)
+
+
+def add_dockernel_versionfile(kernelspec_dir: Path) -> None:
+    """Generate DOCKERNEL file under the specified path.
+
+    Creates a text file with the current version of dockernel package
+
+    Parameters
+    ----------
+    kernelspec_dir
+        Path object to the store where the kernel should be installed.
+    """
+    versionfile_path = kernelspec_dir/DOCKERNEL_VERSIONFILE_FILENAME
+    versionfile_path.write_text(dockernel_version + '\n')
diff --git a/dockernel/version.py b/dockernel/version.py
new file mode 100644
index 0000000..71ee811
--- /dev/null
+++ b/dockernel/version.py
@@ -0,0 +1,4 @@
+# This file is written to by setuptools_scm.
+# The value supplied here is for development purposes only.
+
+__version__ = '0.0.0.dev'
diff --git a/example_dockerfile b/example_dockerfile
index 7dfb2cd..fc034da 100644
--- a/example_dockerfile
+++ b/example_dockerfile
@@ -1,4 +1,4 @@
 FROM python:3.7-slim-buster
 
 RUN pip install --upgrade pip ipython ipykernel
-CMD cat $DOCKERNEL_CONNECTION_FILE; python -m ipykernel_launcher -f $DOCKERNEL_CONNECTION_FILE || true
+CMD python -m ipykernel_launcher -f $DOCKERNEL_CONNECTION_FILE
diff --git a/example_rust_dockerfile b/example_rust_dockerfile
new file mode 100644
index 0000000..26c2b68
--- /dev/null
+++ b/example_rust_dockerfile
@@ -0,0 +1,5 @@
+FROM rust:1.50.0-buster
+
+RUN apt-get update && apt-get install build-essential cmake -y
+RUN cargo install evcxr_jupyter
+CMD evcxr_jupyter --control_file $DOCKERNEL_CONNECTION_FILE
diff --git a/pyproject.toml b/pyproject.toml
index 498d416..6c44890 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,3 +2,4 @@
 requires = ["setuptools>=42", "wheel", "setuptools_scm[toml]>=3.4"]
 
 [tool.setuptools_scm]
+write_to = "dockernel/version.py"
diff --git a/setup.cfg b/setup.cfg
index 7a3001d..34987dd 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -23,6 +23,7 @@ classifiers =
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
     Programming Language :: Python :: Implementation :: CPython
 
 [options]
diff --git a/setup.py b/setup.py
index e02756e..6267b7a 100644
--- a/setup.py
+++ b/setup.py
@@ -1,3 +1,3 @@
 import setuptools
 
-setuptools.setup(use_scm_version=True)
+setuptools.setup(use_scm_version={'write_to': 'dockernel/version.py'})
diff --git a/tests/test_install.py b/tests/test_install.py
index f5f31f8..424d5cd 100644
--- a/tests/test_install.py
+++ b/tests/test_install.py
@@ -4,12 +4,13 @@
 from dockernel.cli import main_arguments
 
 
-class TestKernelspecArgvGeneration:
+# TODO Add tests for Darwin and Windows
+class TestLinuxKernelspecArgvGeneration:
     IMAGE_NAME = 'example/image-name'
 
     @pytest.fixture
     def argv(self):
-        return generate_kernelspec_argv(self.IMAGE_NAME)
+        return generate_kernelspec_argv(self.IMAGE_NAME, 'Linux')
 
     def test_argv_starts_with_usr_bin_env_python_m(self, argv):
         assert argv[:3] == ['/usr/bin/env', 'python', '-m']
diff --git a/tests/test_kernelspec.py b/tests/test_kernelspec.py
index 32cba82..354b329 100644
--- a/tests/test_kernelspec.py
+++ b/tests/test_kernelspec.py
@@ -1,3 +1,4 @@
+import os
 import pytest
 import json
 from dockernel.kernelspec import (Kernelspec, InterruptMode,
@@ -7,6 +8,16 @@
 from pathlib import Path
 
 
+@pytest.yield_fixture
+def environment_variables():
+    starting_state = os.environ.copy()
+
+    yield os.environ
+
+    os.environ.clear()
+    os.environ.update(starting_state)
+
+
 @pytest.fixture
 def tmpdir(tmpdir):
     """Workaround for tmpdir being py.path.LocalPath instead of Path"""
@@ -81,7 +92,10 @@ def test_raises_ValueError_when_directory_name_is_not_store(self, tmpdir):
 
 class TestKernelspecStoreDir:
     @pytest.mark.parametrize('system_type', ('Linux', 'Windows', 'Darwin'))
-    def test_works_for_supported_platforms(self, system_type):
+    def test_works_for_supported_platforms(self, system_type,
+                                           environment_variables):
+        if system_type == 'Windows':
+            environment_variables['APPDATA'] = ''
         user_kernelspec_store(system_type)
 
     def test_raises_TypeError_on_unknown_system(self):