docs: add how to setup dev env in ubuntu (#605)

Author: lionelhorn

DEVELOPMENT.md

@@ -5,7 +5,8 @@
 Deepkit uses NPM and Lerna to manage this monorepo. Local package linking is managed through the NPM Workspaces.
 
 Make sure `libpq5` and `libpq-dev` are installed. 
-These are needed for Postgres client `pg`, which is used in `@deepkit/postgres`.
+These are needed for Postgres client `pg`, which is used in `@deepkit/postgres`.\
+See [Ubuntu requirements setup](docs/setup-env-ubuntu.md) for detailed steps for an Ubuntu system.
 
 Node >= v20 is needed.
 

docs/setup-env-ubundu.md

@@ -0,0 +1,73 @@
+## Setup development environment in Ubuntu
+
+### Step 1: Install `libpq5` and `libpq-dev`
+
+1. **Update your package lists**:
+
+   Open a terminal and run:
+   ```bash
+   sudo apt update
+   ```
+
+2. **Install the packages**:
+
+   Run the following command to install `libpq5` and `libpq-dev`:
+   ```bash
+   sudo apt install libpq5 libpq-dev
+   ```
+
+### Step 2: Set Python to refer to Python 2
+
+Since Python 2 is deprecated and might not be installed by default on newer systems, you'll need to ensure it is installed and set up correctly.
+
+1. **Install Python 2**:
+
+   If Python 2 is not installed, you can install it using:
+   ```bash
+   sudo apt install python2
+   ```
+
+2. **Check if Python 2 is installed**:
+
+   Verify the installation by running:
+   ```bash
+   python2 --version
+   ```
+
+   You should see something like:
+   ```
+   Python 2.7.x
+   ```
+
+3. **Update the `python` command to refer to Python 2**:
+
+   You might need to update the alternatives system to make `python` point to `python2`. Here’s how you can do that:
+
+- **Check current alternatives**:
+  ```bash
+  ls -l /usr/bin/python
+  ```
+
+- **Set `python` to point to `python2`**:
+
+  If `/usr/bin/python` points to Python 3, you can update it using the alternatives system:
+
+  ```bash
+  sudo update-alternatives --install /usr/bin/python python /usr/bin/python2 1
+  ```
+
+- **Verify**:
+
+  Check again to ensure that `python` now refers to Python 2:
+  ```bash
+  python --version
+  ```
+
+  It should display:
+  ```
+  Python 2.7.x
+  ```
+
+### Step 3: Install Node
+
+Refer to [node.js download](https://nodejs.org/en/download) for options on how to install node.