Python3 环境搭建

Python3 下载安装、环境变量配置、运行 Python 与常用配套工具。

Beginner

Key Points装 Python 时务必勾选 Add to PATH；用 python --version 和 pip --version 验证；虚拟环境隔离项目依赖。

Python3 下载

Get the installer for your platform from python.org's Downloads page: 64-bit installer on Windows, universal2 on macOS; on Linux the package manager usually provides it. Pick the current stable release, not a preview.

Windows — python-3.x.x-amd64.exe
macOS — python-3.x.x-macos11.pkg
Linux — apt / dnf / pacman install python3

Python 安装

On the first screen of the Windows installer, tick "Add Python to PATH" — otherwise the shell cannot find python. Under Customize you can also enable pip and tcl/tk.

Python

import sys
import os
import platform

print("executable:", os.path.basename(sys.executable))
print("platform:", platform.system())
print("prefix set:", bool(sys.prefix))

Output

executable: python.exe
platform: Windows
prefix set: True

环境变量配置

PATH must contain both the Python install directory and its Scripts directory: the first gives you python, the second pip. Verify in a new terminal — an already-open one keeps the old environment.

Python

import os
import sys

paths = os.environ.get('PATH', '').split(os.pathsep)
has_python = any('python' in p.lower() for p in paths)
print("path entries:", len(paths) > 0)
print("python in PATH:", has_python)
print("sys.path entries:", len(sys.path) > 0)

Output

path entries: True
python in PATH: True
sys.path entries: True

PATH lets the shell find executables; sys.path lets import find modules. They are unrelated — do not edit PATH to fix an import error.

运行 Python

Three ways to run: interactive python, script python hello.py, module python -m http.server. -c executes a string directly — handy for quick checks.

Python

import subprocess
import sys

r1 = subprocess.run([sys.executable, '-c', 'print(1 + 1)'],
                    capture_output=True, text=True)
print("stdout:", r1.stdout.strip())
print("returncode:", r1.returncode)

r2 = subprocess.run([sys.executable, '-c', 'raise SystemExit(3)'],
                    capture_output=True, text=True)
print("exit on error:", r2.returncode)

Output

stdout: 2
returncode: 0
exit on error: 3

Python3 下载

从 python.org 的 Downloads 页取对应平台的安装包。Windows 用 64-bit installer，macOS 用 universal2 installer，Linux 一般由包管理器提供。选当前稳定版而非最新预览版。

Windows —— python-3.x.x-amd64.exe
macOS —— python-3.x.x-macos11.pkg
Linux —— apt / dnf / pacman 安装 python3

Python 安装

Windows 安装向导第一屏有一个关键的勾选项「Add Python to PATH」，必须勾上，否则命令行找不到 python。选 Customize 时可以顺便勾选 pip 和 tcl/tk。

Python

import sys
import os
import platform

print("executable:", os.path.basename(sys.executable))
print("platform:", platform.system())
print("prefix set:", bool(sys.prefix))

Output

executable: python.exe
platform: Windows
prefix set: True

环境变量配置

PATH 里要有 Python 的安装目录和 Scripts 目录：前者让你能敲 python，后者让你能敲 pip。装完在新开的终端里验证，旧终端不会自动刷新环境变量。

Python

import os
import sys

paths = os.environ.get('PATH', '').split(os.pathsep)
has_python = any('python' in p.lower() for p in paths)
print("path entries:", len(paths) > 0)
print("python in PATH:", has_python)
print("sys.path entries:", len(sys.path) > 0)

Output

path entries: True
python in PATH: True
sys.path entries: True

PATH 是给命令行找可执行文件用的，sys.path 是给 import 找模块用的，两者互不相干。模块导入失败不要改 PATH。

运行 Python

三种运行方式：交互式 python、脚本 python hello.py、模块 python -m http.server。-c 可以直接执行一段字符串，适合快速验证。

Python

import subprocess
import sys

r1 = subprocess.run([sys.executable, '-c', 'print(1 + 1)'],
                    capture_output=True, text=True)
print("stdout:", r1.stdout.strip())
print("returncode:", r1.returncode)

r2 = subprocess.run([sys.executable, '-c', 'raise SystemExit(3)'],
                    capture_output=True, text=True)
print("exit on error:", r2.returncode)

Output

stdout: 2
returncode: 0
exit on error: 3

Python3 环境搭建

Python3 下载

Python 安装

环境变量配置

运行 Python

更多必备工具

Python3 下载

Python 安装

环境变量配置

运行 Python

更多必备工具

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