如何在ubuntu上将python版本从3.7.5降级到3.6.5

Question

因此，目前，我有ubuntu19。Python3.7.5默认提供了它。我需要降级到3.6.5。

编辑：

我正在使用virtualenv

Answer 1

您还可以使用virtualenv使用不同的Python环境。

如果您键入python和tab两次左右，您可能会看到许多可用的Python版本。我之所以这样说是因为当我键入

python3.6 -V

我有

Python 3.6.9

可用。我的python别名是3.7.5

当您键入python时，您可能是指.bashrc中定义的别名

Answer 2

以下内容讨论了从3.6.7升级到3.7.0的过程，但是您可以使用相同的过程进行降级。除非您真的知道自己在做什么，否则不应该更改系统python

首先安装Pyenv

Installlation Instructions are here

查看Pyenv选项

$ pyenv 
pyenv 1.2.14
Usage: pyenv <command> [<args>]

Some useful pyenv commands are:
   commands    List all available pyenv commands
   activate    Activate virtual environment
   commands    List all available pyenv commands
   deactivate   Deactivate virtual environment
   doctor      Verify pyenv installation and deevlopment tools to build pythons.
   exec        Run an executable with the selected Python version
   global      Set or show the global Python version
   help        Display help for a command
   hooks       List hook scripts for a given pyenv command
   init        Configure the shell environment for pyenv
   install     Install a Python version using python-build
   local       Set or show the local application-specific Python version
   prefix      Display prefix for a Python version
   rehash      Rehash pyenv shims (run this after installing executables)
   root        Display the root directory where versions and shims are kept
   shell       Set or show the shell-specific Python version
   shims       List existing pyenv shims
   uninstall   Uninstall a specific Python version
   --version   Display the version of pyenv
   version     Show the current Python version and its origin
   version-file   Detect the file that sets the current pyenv version
   version-name   Show the current Python version
   version-origin   Explain how the current Python version is set
   versions    List all Python versions available to pyenv
   virtualenv   Create a Python virtualenv using the pyenv-virtualenv plugin
   virtualenv-delete   Uninstall a specific Python virtualenv
   virtualenv-init   Configure the shell environment for pyenv-virtualenv
   virtualenv-prefix   Display real_prefix for a Python virtualenv version
   virtualenvs   List all Python virtualenvs found in `$PYENV_ROOT/versions/*'.
   whence      List all Python versions that contain the given executable
   which       Display the full path to an executable

See `pyenv help <command>' for information on a specific command.
For full documentation, see: https://github.com/pyenv/pyenv#readme

查看Python版本

$ pyenv versions
  system
 * 3.6.7 (set by /home/taarimalta/.pyenv/version)

安装新的Python

$ pyenv install 3.7.0
Installing Python-3.7.0...
WARNING: The Python bz2 extension was not compiled. Missing the bzip2 lib?
WARNING: The Python readline extension was not compiled. Missing the GNU readline lib?
WARNING: The Python sqlite3 extension was not compiled. Missing the SQLite3 lib?
Installed Python-3.7.0 to /home/taarimalta/.pyenv/versions/3.7.0

如果遇到_ctypes问题，请安装libffi-dev库

现在查看版本

$ pyenv versions
  system
* 3.6.7 (set by /home/taarimalta/.pyenv/version)
  3.7.0

为本地环境选择3.7.0

$ pyenv local 3.7.0

确认版本已更改

$ pyenv versions
  system
  3.6.7
 * 3.7.0 (set by /home/taarimalta/.python-version)

$ python
Python 3.7.0 (default, Jan  1 2020, 10:52:57) 
[GCC 9.2.1 20191008] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>