在Linux系统中配置环境变量以切换不同版本Python的方法与实践

这个Linux系统下本来装了python2&＃xff0c;而且是好几个。还装了anaconda&＃xff0c;自带python3。我的目的是想让python环境变量默认使用python3。

查看当前python版本&＃xff1a;

[liusiyi&＃64;localhost ~]$ python --version

Python 2.7.5

用which 看一下当前使用的python的路径&＃xff1a;

[liusiyi&＃64;localhost ~]$ which python

/usr/bin/python

用whereis 确认所有python路径(但这个不全&＃xff0c;因为没有anaconda)&＃xff1a;

[liusiyi&＃64;localhost ~]$ whereis python

python: /usr/bin/python /usr/bin/python2.7 /usr/bin/python2.7-config /usr/lib/python2.7 /usr/lib64/python2.7 /etc/python /usr/include/python2.7 /usr/share/man/man1/python.1.gz

改用echo $PATH再次确认(这里也没包含anaconda)&＃xff1a;

[liusiyi&＃64;localhost ~]$ echo $PATH

/appcom/kylin/bin:/appcom/hadoop/bin:/appcom/hadoop/sbin:/usr/lib/jdk/bin:/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/home/shijuan355/bin:/appcom/hadoop/bin:/appcom/hadoop/sbin:/home/shijuan355/bin:/appcom/ganglia/sbin:/appcom/ganglia/bin:/appcom/sqoop/bin:/appcom/hive/bin:/appcom/hbase/bin:/appcom/zookeeper/bin:/appcom/R/bin:/appcom/apache/bin:/appcom/oozie/bin:/appcom/btrace/bin:/appcom/storm/bin:/appcom/rocketmq//bin:/appcom/hbase/bin:/appcom/hbase/sbin:/appcom/R2/bin:/appcom/R3/bin:/appcom/spark/bin:/appcom/spark/sbin:/appcom/kafka/bin:/appcom/flume/bin:/appcom/odpp/bin:

用export PATH&＃61;添加python3路径&＃xff1a;

[liusiyi&＃64;localhost ~]$ export PATH&＃61;/appcom/AnacondaInstall/anaconda3/bin:$PATH

这时候用python --version 看还是Python 2.7.5。因为bash命令export PATH&＃61;/appcom/AnacondaInstall/anaconda3/bin:$PATH&＃xff0c;使PATH自增&＃xff0c;既PATH&＃61;PATH&＃43;"/appcom/AnacondaInstall/anaconda3/bin:"&＃xff1b;通常是把这行bash命令写到末尾。

下面采用在~/.bashrc 里添加一行“export PATH&＃61;/appcom/AnacondaInstall/anaconda3/bin:$PATH”的方式&＃xff0c;这个只对当前用户生效&＃xff0c;是比较稳妥的做法。

修改前的 ~/.bashrc&＃xff1a;

[liusiyi&＃64;localhost ~]$ cat ~/.bashrc

# .bashrc

# Source global definitions

if [ -f /etc/bashrc ]; then

. /etc/bashrc

fi

# Uncomment the following line if you don&＃39;t like systemctl&＃39;s auto-paging feature:

# export SYSTEMD_PAGER&＃61;

# User specific aliases and functions

修改后的 ~/.bashrc&＃xff0c;最后多了一行&＃xff1a;

[liusiyi&＃64;localhost ~]$ cat ~/.bashrc

# .bashrc

# Source global definitions

if [ -f /etc/bashrc ]; then

. /etc/bashrc

fi

# Uncomment the following line if you don&＃39;t like systemctl&＃39;s auto-paging feature:

# export SYSTEMD_PAGER&＃61;

# User specific aliases and functions

export PATH&＃61;/appcom/AnacondaInstall/anaconda3/bin:$PATH

这时候有两个方法让这个环境变量生效。1、关闭当前终端窗口&＃xff0c;重新打开一个新终端窗口就能生效&＃xff1b;2、输入“source ~/.bashrc”命令&＃xff0c;立即生效。

现在再来查看&＃xff0c;python3已经成为默认的环境变量&＃xff1a;

[liusiyi&＃64;localhost ~]$ which python

/appcom/AnacondaInstall/anaconda3/bin/python

[liusiyi&＃64;localhost ~]$ python --version

Python 3.6.3 :: Anaconda, Inc.

还有很多其他方法能实现不同版本的python切换环境变量默认值。很多文章都讲过。

python中path路径的优先匹配顺序&＃xff1a;https://blog.csdn.net/wangzhaotongalex/article/details/50127431

切换Python2和Python3的4种方法&＃xff1a;https://blog.csdn.net/jasonfqw/article/details/72974187