Two ways to change the default Python version of Ubuntu python-> Anaconda__python

When you install Debian Linux, the installation process may also provide you with multiple Python versions available, so there will be multiple Python executable binaries in the system. You can use the LS command to see that Python binaries are available in your system as follows.

$ ls/usr/bin/python*
/usr/bin/python  /usr/bin/python2  /usr/bin/python2.7  /usr/bin/python3  / usr/bin/python3.4  /usr/bin/python3.4m  /usr/bin/python3m

Perform the following command to view the default Python version information:

$ python--version
python 2.7.8

1. Modify Python version based on User:

To modify the Python version for a particular user, simply create an alias (alias) under its home directory. Open the user's ~/.BASHRC file and add new alias information to modify the Python version used by default.

Alias python= '/usr/bin/python3.4 '

Once you have done so, log back in or reload the. bashrc file to make the operation effective.

$ . ~/.bashrc

Check the current Python version.

$ python--version
python 3.4.2

2. Modify Python version at System level

We can use Update-alternatives to change the Python version for the entire system. Log in as root, first listing all available Python alternative version information:

# update-alternatives--list python
update-alternatives:error:no alternatives for Python

If the error message shown above appears, the alternate version of Python is not yet recognized by the update-alternatives command. To solve this problem, we need to update the alternate list and put python2.7 and python3.4 in it.

# 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

How to view the current working directory of Python, you can import the Sys sys.executable by doing the following

'/root/anaconda3/bin/python '

The--install option uses more than one parameter to create a symbolic link. The last parameter specifies the priority of this option, and if we do not manually set an alternate option, the option with the highest priority is selected. In this example, we set the priority for/usr/bin/python3.4 to 2, so the update-alternatives command automatically sets it to the default Python version.

# python--version
python 3.4.2

Next, we list the available Python alternate versions again.

# update-alternatives--list python
/usr/bin/python2.7
/usr/bin/python3.4

From now on, we can use the commands below to switch at any time in the list of Python replacements.

# update-alternatives--config python
# python--version
python 2.7.8

3. Remove Alternate Version

Once a substitute version of Python is no longer present in our system, we can remove it from the Update-alternatives list. For example, we can remove the python2.7 version from the list.

# 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

Or remove a soft connection

Rm-rf/data/logs 
ln-s/temp/logs/data/logs