JALE/docs/Installing-Python.md

This guide walks you through the steps to set up Python and manage virtual environments using pyenv and pyenv-virtualenv on macOS and Linux.

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Prerequisites

Before you start, ensure you have the following installed:

macOS

• Homebrew:

  Check if Homebrew is already installed:

  brew
  

  If this throws an error:

  /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
  

  Follow the instructions provided by the Homebrew installer to add brew to your path.

• Install required dependencies:

  brew install openssl readline sqlite3 xz zlib tcl-tk git libomp
  

Linux (Debian/Ubuntu-based systems)

• Install build dependencies:

  sudo apt update && sudo apt install -y \
      make build-essential libssl-dev zlib1g-dev \
      libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm \
      libncurses5-dev libncursesw5-dev xz-utils tk-dev \
      libffi-dev liblzma-dev python-openssl git
  

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Step 1: Install pyenv

1. Run the following command to install pyenv:

   curl https://pyenv.run | bash
   

   Alternatively, use wget:

   wget -qO- https://pyenv.run | bash
   

2. Find out which configuration file your shell is loading. Most common: ~/.bashrc, ~/.zshrc or ~/.bash_profile.

   e.g.

   echo $SHELL
   

3. Run the command corresponding to your shell configuration file. (~/.bashrc, ~/.zshrc, etc.):

   echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bashrc
   echo 'command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bashrc
   echo 'eval "$(pyenv init --path)"' >> ~/.bashrc
   echo 'eval "$(pyenv init -)"' >> ~/.bashrc
   

   echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.zshrc
   echo 'command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.zshrc
   echo 'eval "$(pyenv init --path)"' >> ~/.zshrc
   echo 'eval "$(pyenv init -)"' >> ~/.zshrc
   

4. Reload your shell:

   exec $SHELL
   

5. Verify the installation:

   pyenv --version
   

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Step 2: Install pyenv-virtualenv

1. Install the pyenv-virtualenv plugin:

   git clone https://github.com/pyenv/pyenv-virtualenv.git $(pyenv root)/plugins/pyenv-virtualenv
   

2. Add the following line to your shell configuration file (~/.bashrc, ~/.zshrc, etc.):

   eval "$(pyenv virtualenv-init -)"
   

3. Reload your shell:

   exec $SHELL
   

4. Verify the installation:

   pyenv virtualenv --version
   

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Step 3: Install a Python Version and setup a virtual environment

1. Install Python Version 3.11

   pyenv install 3.11
   

2. Create a virtual environment with a name of your choice:

   pyenv virtualenv 3.11 <env-name>
   

3. Set the virtual environment as the global Python Environment:

   pyenv global <env-name>
   

You are now ready to install JALE. Installing JALE

---

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Useful pyenv commands

• List all available Python versions:

  pyenv install --list
  

• Install a specific Python version:

  pyenv install <version>
  

  Example:

  pyenv install 3.11.5
  

• Set the global Python version:

  pyenv global <version>
  

  Example:

  pyenv global 3.11.5
  

• Verify the installed Python version:

  python --version
  

• Check all installed Python versions:

  pyenv versions
  

• Create a virtual environment:

  pyenv virtualenv <python-version> <env-name>
  

  Example:

  pyenv virtualenv 3.11.5 myenv
  

• Activate the virtual environment:

  pyenv activate <env-name>
  

  Example:

  pyenv activate myenv
  

• Deactivate the virtual environment:

  pyenv deactivate
  

• List all virtual environments:

  pyenv virtualenvs
  

• Set a local Python version or virtual environment for a specific project directory:

  pyenv local <version-or-env>
  

  Example:

  pyenv local myenv
  

• Remove a virtual environment:

  pyenv uninstall <env-name>
  

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Troubleshooting

macOS Specific Issues

• If you use macOS with M1/M2 chips, consider setting additional flags when installing Python:

  CFLAGS="-I$(brew --prefix openssl)/include" \
  LDFLAGS="-L$(brew --prefix openssl)/lib" \
  pyenv install <version>
  

Linux Specific Issues

• If you encounter build issues while installing Python, ensure all required dependencies (listed in prerequisites) are installed.