一、查看python版本
python --verstion
二、查看python版本指向
ls -l /usr/bin | grep python
此命令信息较详细,也可使用简洁命令:ls /usr/bin/python*
三、直接升级
从版本2升级到3,可使用命令:apt-get install python3.7。若报错,只能从源码安装。
若报此错E: Couldn't find any package by regex 'python3.7-dev'则
sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt-get update
sudo apt-get install python3.7
或
sudo add-apt-repository ppa:jonathonf/python-3.7
sudo apt-get update
sudo apt-get install python3.7
若上述运行sudo add-apt-repository ppa:deadsnakes/ppa 出现 “bash: add-apt-repository: command not found” 则先运行:
sudo apt-get install -y software-properties-common
四、切换python版本
update-alternatives --list python#查看可替代python版本,如果报错没有可替代版本,则需要更新替代列表(操作如下)
update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1
update-alternatives --install /usr/bin/python python /usr/bin/python3.5 2
若报错:update-alternatives: error: no alternatives for python,说明python 的替代版本尚未被 update-alternatives 命令识别,要更新一下替代列表,将 python2.7 和 python3.*放入其中。
# update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1
update-alternatives: using /usr/bin/python2.7 to provide /usr/bin/python (python) in auto mode
# update-alternatives --install /usr/bin/python python /usr/bin/python3.4 2
update-alternatives: using /usr/bin/python3.4 to provide /usr/bin/python (python) in auto mode
也可移除代替版本:
# update-alternatives --remove python /usr/bin/python2.7
update-alternatives: removing manually selected alternative - switching python to auto mode
update-alternatives: using /usr/bin/python3.4 to provide /usr/bin/python (python) in auto mode
五、进行切换
update-alternatives --config python#选择标号