py-venv-setup.sh

# Usage:
#   venv_setup <venv path> [<python version>] [<requirements.txt path>]
# 
# If <python version> is left "", then the default python interpreter
# will be used, otherwise provide a number like "3.11"
#
venv_setup() { 
    local VENV_DIR="$1"
    local PY_VER="${2-}"
    local REQUIREMENTS_TXT="$3"

    local PY="python$PY_VER"
    local VENV_PY="$VENV_DIR/bin/python"

    "$PY" --version &> /dev/null || (echo "Error: '$PY' not installed" && exit 1)

    if ! "$VENV_PY" --version &> /dev/null; then
        if [ -d "$VENV_DIR" ]; then
            echo "Removing existing virtual enviornment..."
            rm -rf "$VENV_DIR"
        fi
        echo "Creating new virtual enviornment..."
        "$PY" -m venv "$VENV_DIR"
    fi
    
    if [[ -n "$REQUIREMENTS_TXT" && -f "$REQUIREMENTS_TXT" ]]; then        
        echo "Updating packages..."
        "$VENV_PY" -m pip install -q --upgrade pip
        "$VENV_PY" -m pip install -q -r "$REQUIREMENTS_TXT"
    fi
}