Mac 安装 Python 看这里就够了，Python2、Python3 再也不懵了

Mac 安装 Python2、Python3 。

零、基础准备

• 官网
  • https://www.python.org/
• 下载入口
  • https://www.python.org/downloads/
  • https://www.python.org/downloads/macos/

一、安装包下载及安装

安装包下载的页面路径是：官网>>> Downloads>>> macOS

其他平台根据请自己的实际情况选择

安装包下载的页面路径也可以是：官网>>> Downloads(点击)

进入到版本选择页面

最上面是最新的 Release 版本，分别是2.x的最新版本和3.x的最新版。

可以下载最新的 Release 版本进行安装，也可以通过搜索选择自己想要的版本进行安装。

通过搜索找到「2.7.16」

通过搜索找到「3.9.9」

强烈推荐下载最新的 Release 版进行安装

点击对应的链接分别下载即可(下载的过程中注意操作系统的架构和位数)。

下载「2.7.18」

下载「3.10.6」

下载好的安装包

使用下载好的安装包一直「下一步」即可安装对应版本的 python。

二、安装确认

1、Python2

• 查看版本号

$ python -VPython 2.7.18

• 帮助命令

$ python -husage: /Library/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python [option] ... [-c cmd | -m mod | file | -] [arg] ...Options and arguments (and corresponding environment variables):-b : issue warnings about comparing bytearray with unicode (-bb: issue errors)-B : don't write .py[co] files on import; also PYTHONDONTWRITEBYTECODE=x-c cmd : program passed in as string (terminates option list)-d : debug output from parser; also PYTHONDEBUG=x-E : ignore PYTHON* environment variables (such as PYTHONPATH)-h : print this help message and exit (also --help)-i : inspect interactively after running script; forces a prompt even if stdin does not appear to be a terminal; also PYTHONINSPECT=x-m mod : run library module as a script (terminates option list)-O : optimize generated bytecode slightly; also PYTHONOPTIMIZE=x-OO: remove doc-strings in addition to the -O optimizations-R : use a pseudo-random salt to make hash() values of various types be unpredictable between separate invocations of the interpreter, as a defense against denial-of-service attacks-Q arg : division options: -Qold (default), -Qwarn, -Qwarnall, -Qnew-s : don't add user site directory to sys.path; also PYTHONNOUSERSITE-S : don't imply 'import site' on initialization-t : issue warnings about inconsistent tab usage (-tt: issue errors)-u : unbuffered binary stdout and stderr; also PYTHONUNBUFFERED=x see man page for details on internal buffering relating to '-u'-v : verbose (trace import statements); also PYTHONVERBOSE=x can be supplied multiple times to increase verbosity-V : print the Python version number and exit (also --version)-W arg : warning control; arg is action:message:category:module:lineno also PYTHONWARNINGS=arg-x : skip first line of source, allowing use of non-Unix forms of #!cmd-3 : warn about Python 3.x incompatibilities that 2to3 cannot trivially fixfile : program read from script file-: program read from stdin (default; interactive mode if a tty)arg ...: arguments passed to program in sys.argv[1:]Other environment variables:PYTHONSTARTUP: file executed on interactive startup (no default)PYTHONPATH : ':'-separated list of directories prefixed to the default module search path.The result is sys.path.PYTHONHOME : alternate  directory (or :). The default module search path uses /pythonX.X.PYTHONCASEOK : ignore case in 'import' statements (Windows).PYTHONIOENCODING: Encoding[:errors] used for stdin/stdout/stderr.PYTHONHASHSEED: if this variable is set to 'random', the effect is the same as specifying the -R option: a random value is used to seed the hashes of str, bytes and datetime objects.It can also be set to an integer in the range [0,4294967295] to get hash values with a predictable seed.

2、Python3

• 查看版本号

$ python3 -VPython 3.10.6

• 帮助命令

$ python3 -husage: /Library/Frameworks/Python.framework/Versions/3.10/bin/python3 [option] ... [-c cmd | -m mod | file | -] [arg] ...Options and arguments (and corresponding environment variables):-b : issue warnings about str(bytes_instance), str(bytearray_instance) and comparing bytes/bytearray with str. (-bb: issue errors)-B : don't write .pyc files on import; also PYTHONDONTWRITEBYTECODE=x-c cmd : program passed in as string (terminates option list)-d : turn on parser debugging output (for experts only, only works on debug builds); also PYTHONDEBUG=x-E : ignore PYTHON* environment variables (such as PYTHONPATH)-h : print this help message and exit (also -" /> directory (or :). The default module search path uses /lib/pythonX.X.PYTHONPLATLIBDIR : override sys.platlibdir.PYTHONCASEOK : ignore case in 'import' statements (Windows).PYTHONUTF8: if set to 1, enable the UTF-8 mode.PYTHONIOENCODING: Encoding[:errors] used for stdin/stdout/stderr.PYTHONFAULTHANDLER: dump the Python traceback on fatal errors.PYTHONHASHSEED: if this variable is set to 'random', a random value is used to seed the hashes of str and bytes objects.It can also be set to an integer in the range [0,4294967295] to get hash values with a predictable seed.PYTHONMALLOC: set the Python memory allocators and/or install debug hooks on Python memory allocators. Use PYTHONMALLOC=debug to install debug hooks.PYTHONCOERCECLOCALE: if this variable is set to 0, it disables the locale coercion behavior. Use PYTHONCOERCECLOCALE=warn to request display of locale coercion and locale compatibility warnings on stderr.PYTHONBREAKPOINT: if this variable is set to 0, it disables the default debugger. It can be set to the callable of your debugger of choice.PYTHONDEVMODE: enable the development mode.PYTHONPYCACHEPREFIX: root directory for bytecode cache (pyc) files.PYTHONWARNDEFAULTENCODING: enable opt-in EncodingWarning for 'encoding=None'.

三、其他

除了使用python、python3命令来调用对应版本的 python 外，还可以使用如下的命令来调用对应版本的 python。

$ python2 -VPython 2.7.18$ python2.7 -VPython 2.7.18$ python3.10 -VPython 3.10.6

这些都可以可以在 /usr/local/bin 这个目录下看到相关命令对应的「软连接」。

$ pwd/usr/local/bin$ ls -l | grep pythonpython -> ../../../Library/Frameworks/Python.framework/Versions/2.7/bin/pythonpython-config -> ../../../Library/Frameworks/Python.framework/Versions/2.7/bin/python-configpython2 -> ../../../Library/Frameworks/Python.framework/Versions/2.7/bin/python2python2-config -> ../../../Library/Frameworks/Python.framework/Versions/2.7/bin/python2-configpython2.7 -> ../../../Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7python2.7-config -> ../../../Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7-configpython3 -> ../../../Library/Frameworks/Python.framework/Versions/3.10/bin/python3python3-config -> ../../../Library/Frameworks/Python.framework/Versions/3.10/bin/python3-configpython3-intel64 -> ../../../Library/Frameworks/Python.framework/Versions/3.10/bin/python3-intel64python3.10 -> ../../../Library/Frameworks/Python.framework/Versions/3.10/bin/python3.10python3.10-config -> ../../../Library/Frameworks/Python.framework/Versions/3.10/bin/python3.10-configpython3.10-intel64 -> ../../../Library/Frameworks/Python.framework/Versions/3.10/bin/python3.10-intel64pythonw -> ../../../Library/Frameworks/Python.framework/Versions/2.7/bin/pythonwpythonw2 -> ../../../Library/Frameworks/Python.framework/Versions/2.7/bin/pythonw2pythonw2.7 -> ../../../Library/Frameworks/Python.framework/Versions/2.7/bin/pythonw2.7

PS：python2和python3的兼容性一直被广大开发者诟病。