Running Multiple Python Versions
Question:
I want to run multiple Python versions in my box. Is there any version manager for Python where I can switch between multiple Python versions without having to call the full path of the Python binary? I have tried virtualenv and it seems to only cover problems running multiple Python library versions.
Thanks for your help.
Answers:
When calling python from bash you could try an alias.
user@machine:~$ alias python1234='/usr/bin/python2.5'
user@machine:~$ python1234
Python 2.5.4 (r254:67916, Jan 20 2010, 21:44:03)
[GCC 4.3.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
Let’s say you have a script called script.py with following content:
import sys
print sys.version
So, launching a script with a different version of python looks like:
user@machine:~$ python script.py
2.6.2 (release26-maint, Apr 19 2009, 01:56:41)
[GCC 4.3.3]
user@machine:~$ python1234 script.py
2.5.4 (r254:67916, Jan 20 2010, 21:44:03)
[GCC 4.3.3]
You don’t have to use the full path.
user@machine:$ python2.5
Python 2.5.5 (r255:77872, Sep 14 2010, 17:16:34)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
user@machine:$ python2.6
Python 2.6.5 (r265:79063, Apr 16 2010, 13:09:56)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
Does that answer your question?
I use virtualenv to keep track of different environments I need for my projects. I may setup django 1.0 in one environment or django 1.2 for another. You can use it to set which version of python you’d like to use in a particular environment as well. Here’s the link to the site which has great samples and tutorials for how to get running: http://pypi.python.org/pypi/virtualenv
Installing Multiple Interpreter Versions
node-build is a common tool for installing multiple Node versions. python-build is a common tool for installing multiple Python versions.
node-build installation:
brew install node-build
python-build installation:
git clone https://github.com/pyenv/pyenv.git
cd pyenv/plugins/python-build
./install.sh
node-build usage:
node-build 14.20.1 ~/.nodes/node-14.20.1
node-build 16.17.1 ~/.nodes/node-16.17.1
python-build usage:
python-build 3.8.10 ~/.pythons/python-3.8.10
python-build 3.9.13 ~/.pythons/python-3.9.13
Managing Multiple Interpreter Versions
rvm, rbenv, and chruby are common tools for managing multiple Ruby versions. They inspired nvm, nodenv, and chnode which are equivalent tools for managing multiple Node versions. They also inspired pyenv and chpython which are equivalent tools for managing multiple Python versions (there is no rvm equivalent as far as I know).
To automatically switch the Ruby version bound to the ruby command depending on the version defined in the .ruby-version file of the current working directory or the nearest parent directory, the tools use different strategies (from the heaviest to the lightest):
rvm updates the PATH environment variable before each execution of the cd command with a function redefining the cd command;rbenv uses a proxy ruby command (shim);chruby updates the PATH environment variable before each execution of a shell command with a function hooked into the shell with preexec_functions for Zsh and PROMPT_COMMAND for Bash.
The drawback of the rvm strategy is that it is invasive and slow. The drawback of the rbenv strategy is that the man command cannot find the manual page of the ruby command anymore because of the shim indirection. The chruby strategy does not have those issues so chruby is the recommended tool.
chnode installation:
brew tap tkareine/chnode
brew install tkareine/chnode/chnode
echo "source /usr/local/opt/chnode/share/chnode/chnode.sh" >>~/.zshrc
echo "source /usr/local/opt/chnode/share/chnode/auto.sh" >>~/.zshrc
echo "precmd_functions+=(chnode_auto)" >>~/.zshrc
chpython installation:
git clone https://github.com/kisoku/chpython.git
cd chpython
make install
echo "source /usr/local/share/chpython/chpython.sh" >>~/.zshrc
echo "source /usr/local/share/chpython/auto.sh" >>~/.zshrc
chnode usage:
echo $PATH
# /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chnode
# node-14.20.1
# node-16.17.1
chnode 16.17.1
echo $PATH
# /Users/me/.nodes/node-16.17.1/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chnode
# node-14.20.1
# * node-16.17.1
echo 14.20.1 >.node-version
echo $PATH
# /Users/me/.nodes/node-14.20.1/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chnode
# * node-14.20.1
# node-16.17.1
chpython usage:
echo $PATH
# /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chpython
# python-3.8.10
# python-3.9.13
chpython 3.9.13
echo $PATH
# /Users/me/.pythons/python-3.9.13/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chpython
# python-3.8.10
# * python-3.9.13
echo 3.8.10 >.python-version
echo $PATH
# /Users/me/.pythons/python-3.8.10/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chpython
# * python-3.8.10
# python-3.9.13
I want to run multiple Python versions in my box. Is there any version manager for Python where I can switch between multiple Python versions without having to call the full path of the Python binary? I have tried virtualenv and it seems to only cover problems running multiple Python library versions.
Thanks for your help.
When calling python from bash you could try an alias.
user@machine:~$ alias python1234='/usr/bin/python2.5'
user@machine:~$ python1234
Python 2.5.4 (r254:67916, Jan 20 2010, 21:44:03)
[GCC 4.3.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
Let’s say you have a script called script.py with following content:
import sys
print sys.version
So, launching a script with a different version of python looks like:
user@machine:~$ python script.py
2.6.2 (release26-maint, Apr 19 2009, 01:56:41)
[GCC 4.3.3]
user@machine:~$ python1234 script.py
2.5.4 (r254:67916, Jan 20 2010, 21:44:03)
[GCC 4.3.3]
You don’t have to use the full path.
user@machine:$ python2.5
Python 2.5.5 (r255:77872, Sep 14 2010, 17:16:34)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
user@machine:$ python2.6
Python 2.6.5 (r265:79063, Apr 16 2010, 13:09:56)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
Does that answer your question?
I use virtualenv to keep track of different environments I need for my projects. I may setup django 1.0 in one environment or django 1.2 for another. You can use it to set which version of python you’d like to use in a particular environment as well. Here’s the link to the site which has great samples and tutorials for how to get running: http://pypi.python.org/pypi/virtualenv
Installing Multiple Interpreter Versions
node-build is a common tool for installing multiple Node versions. python-build is a common tool for installing multiple Python versions.
node-build installation:
brew install node-build
python-build installation:
git clone https://github.com/pyenv/pyenv.git
cd pyenv/plugins/python-build
./install.sh
node-build usage:
node-build 14.20.1 ~/.nodes/node-14.20.1
node-build 16.17.1 ~/.nodes/node-16.17.1
python-build usage:
python-build 3.8.10 ~/.pythons/python-3.8.10
python-build 3.9.13 ~/.pythons/python-3.9.13
Managing Multiple Interpreter Versions
rvm, rbenv, and chruby are common tools for managing multiple Ruby versions. They inspired nvm, nodenv, and chnode which are equivalent tools for managing multiple Node versions. They also inspired pyenv and chpython which are equivalent tools for managing multiple Python versions (there is no rvm equivalent as far as I know).
To automatically switch the Ruby version bound to the ruby command depending on the version defined in the .ruby-version file of the current working directory or the nearest parent directory, the tools use different strategies (from the heaviest to the lightest):
rvmupdates thePATHenvironment variable before each execution of thecdcommand with a function redefining thecdcommand;rbenvuses a proxyrubycommand (shim);chrubyupdates thePATHenvironment variable before each execution of a shell command with a function hooked into the shell withpreexec_functionsfor Zsh andPROMPT_COMMANDfor Bash.
The drawback of the rvm strategy is that it is invasive and slow. The drawback of the rbenv strategy is that the man command cannot find the manual page of the ruby command anymore because of the shim indirection. The chruby strategy does not have those issues so chruby is the recommended tool.
chnode installation:
brew tap tkareine/chnode
brew install tkareine/chnode/chnode
echo "source /usr/local/opt/chnode/share/chnode/chnode.sh" >>~/.zshrc
echo "source /usr/local/opt/chnode/share/chnode/auto.sh" >>~/.zshrc
echo "precmd_functions+=(chnode_auto)" >>~/.zshrc
chpython installation:
git clone https://github.com/kisoku/chpython.git
cd chpython
make install
echo "source /usr/local/share/chpython/chpython.sh" >>~/.zshrc
echo "source /usr/local/share/chpython/auto.sh" >>~/.zshrc
chnode usage:
echo $PATH
# /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chnode
# node-14.20.1
# node-16.17.1
chnode 16.17.1
echo $PATH
# /Users/me/.nodes/node-16.17.1/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chnode
# node-14.20.1
# * node-16.17.1
echo 14.20.1 >.node-version
echo $PATH
# /Users/me/.nodes/node-14.20.1/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chnode
# * node-14.20.1
# node-16.17.1
chpython usage:
echo $PATH
# /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chpython
# python-3.8.10
# python-3.9.13
chpython 3.9.13
echo $PATH
# /Users/me/.pythons/python-3.9.13/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chpython
# python-3.8.10
# * python-3.9.13
echo 3.8.10 >.python-version
echo $PATH
# /Users/me/.pythons/python-3.8.10/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
chpython
# * python-3.8.10
# python-3.9.13