Use a PIP workspace for colcon and vcs

ionic/install_ubuntu_src.md

@@ -29,32 +29,17 @@ sudo apt install python3-pip lsb-release gnupg curl
 
 ## vcstool and colcon from pip
 
-PIP is available on all platforms:
+PIP is available on all platforms. Using a PIP workspace to install the tools:
 
 ```bash
-pip install vcstool || pip3 install vcstool
+python3 -m venv $HOME/vcs_colcon_installation
+. $HOME/vcs_colcon_installation/bin/activate
+pip3 install vcstool colcon-common-extensions
 ```
 
-```bash
-pip install -U colcon-common-extensions || pip3 install -U colcon-common-extensions
-```
-
-Check that no errors were printed while installing with PIP. If your system is not recognising the commands, and you're using a system that is compatible with Debian or Ubuntu packages, see the instructions below to install using `apt`.
-
-After installing `vcstool` and `colcon` with PIP, you may need to add their executables to your `$PATH`.
-Check where the installation of these packages took place:
-
-```bash
-pip show vcstool || pip3 show vcstool | grep Location
-
-pip show colcon-common-extensions || pip3 show colcon-common-extensions | grep Location
-```
-
-If your install path is prefixed with `$HOME/.local`, you'll probably need to add the executables within this directory to your `$PATH` in order to avoid "command not found" errors when using `vcstool` and `colcon` later on:
-
-```bash
-export PATH=$PATH:$HOME/.local/bin/
-```
+`vcs` and `colcon` are now available from the PIP workspace in the current
+terminal. For using them in other terminals run the `activate` script as
+done above.
 
 ## vcstool and colcon from apt