Automate Python Virtual Environment with a Script - https://tech.serhatteker.com/post/2022-04/automate-python-virtualenv

ve

#!/usr/bin/env bash
# -*- coding: utf-8 -*-
# vim: set ft=sh et ts=4 sw=4 sts=4:
# =================================================================================================
#
# Copyright 2022 Serhat Teker <me@serhatteker.com>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
#
# File                  : ve
# Description           : Create/activate a Python virtual environment in the current directory
# Author                : Serhat Teker <me@serhatteker.com>
# Date                  : 2022-05-10T18:58:06+0300 | 1652198286
# Last Modified Date    : 2026-08-24T00:32:25+0300 | 1787520745
# Notes                 : Checks whether a virtualenv exists in the current working directory.
#                         If not, creates and activates one. If already inside a virtualenv,
#                         warns about it.
# Usage                 :
#
# Make it executable and put it in your $PATH. Or put it in your zsh/bash/fish functions.
# $ chmod +x ./ve && mv ./ve $HOME/.local/bin
#
# How to run:
# Without arguments it will create virtualenv named `.venv` with `python3.9` version
# $ ve
# or for a specific python version
# $ ve python3.11
# or for a specific python version and environment name;
# $ ve python3.11 ./.venv-diff
#
# For detailed tutorial look at the post:
# https://tech.serhatteker.com/post/2022-04/automate-python-virtualenv
# =================================================================================================

# Bash safeties: exit on error, no unset variables, pipelines can't hide errors
set -o errexit
set -o nounset
set -o pipefail


# Logical conditions:
# 0. If not already in virtualenv:
# 0.1. If virtualenv already exists activate it,
# 0.2. If not create it with global packages, update pip then activate it
# 1. If already in virtualenv: just give info
ve() {
    local py="${1:-python3.9}"   # default python version is python3.9
    local venv="${2:-./.venv}"   # default virtual environment name is .venv

    local bin="${venv}/bin/activate"

    # If not already in virtualenv
    # $VIRTUAL_ENV is being set from $venv/bin/activate script
    if [ -z "${VIRTUAL_ENV:-}" ]; then
        if [ ! -d "${venv}" ]; then
            echo "Creating and activating virtual environment ${venv}"
            "${py}" -m venv "${venv}" --system-site-packages
            echo "export PYTHON=${py}" >> "${bin}"   # overwrite ${python} on .zshenv
            source "${bin}"
            echo "Upgrading pip"
            "${py}" -m pip install --upgrade pip
        else
            echo "Virtual environment ${venv} already exists, activating..."
            source "${bin}"
        fi
    else
        echo "Already in a virtual environment!"
    fi
}

ve "$@"