Difference between revisions of "Set up a Python virtual environment"

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Python virtual environments run their own site directories, allowing them to be optionally separated from system directories. This can easily avoid a potential nightmare of version conflicts - one piece of software on your system may require a certain version to run, while another make require a different one.
Python virtual environments run their own site directories, allowing them to be optionally isolated from system directories. This can easily avoid a potential nightmare of version conflicts - one piece of software on your system may require a certain version to run, while another make require a different one.


== Creating the virtual environment ==
== Create ==
<code>venv</code> is a tool that can be used to create an environment:
If you are using Python 3, you can use <code>venv</code>, which is part of its standard library.


<syntaxhighlight lang="bash">
<syntaxhighlight lang="bash">
Line 8: Line 8:
</syntaxhighlight>
</syntaxhighlight>


To activate the virtual environment, run:
When this is run, <code>venv</code> creates the target directory (in this case, named <code>venv</code>), and any parent directories that don't exist yet. It also puts a <code>pyvenv.cfg</code> file with a <code>home</code> key that points to the installation of Python from where the command was run.


== Activate ==
<syntaxhighlight lang="bash">
<syntaxhighlight lang="bash">
source venv/bin/activate
source venv/bin/activate
</syntaxhighlight>
</syntaxhighlight>


You will see the prompt change to something like this:
You will see the prompt change to display <code>(venv)</code> at the beginning of the line:
<syntaxhighlight lang="bash" line>
<syntaxhighlight lang="bash">
(venv)Username@Computer myfolder %
(venv) Username@Computer myfolder %
</syntaxhighlight>
 
== Use ==
Install dependencies within the new Python virtual environment, using <code>pip</code>, the default package manager for Unix-like systems such as Mac OS and Linux. Swap out the {packagename} for the package you want to install.
 
<syntaxhighlight lang="bash">
pip install {packagename}
</syntaxhighlight>
 
== Deactivate ==
To stop it, type:
 
<syntaxhighlight lang="bash">
deactivate
</syntaxhighlight>
</syntaxhighlight>


To close it, simply type
== Close ==
Simply type


<syntaxhighlight lang="bash">
<syntaxhighlight lang="bash">
exit
exit
</syntaxhighlight>
</syntaxhighlight>
== Remove ==
To remove a Python virtual environment, first deactivate it. Then you can use <code>rm</code> to remove it.
<syntaxhighlight lang="bash">
rm -r venv
</syntaxhighlight>
A more thorough method is to specify removal of the files and folders made when the environment was created. In the folder where the venv is, run
<syntaxhighlight lang="bash">
rm -r bin include lib lib64 pyvenv.cfg share
</syntaxhighlight>
[[Category:Cookbook]]
[[Category:Python]]

Latest revision as of 20:56, 4 November 2021

Python virtual environments run their own site directories, allowing them to be optionally isolated from system directories. This can easily avoid a potential nightmare of version conflicts - one piece of software on your system may require a certain version to run, while another make require a different one.

Create

If you are using Python 3, you can use venv, which is part of its standard library. 

python3 -m venv venv

When this is run, venv creates the target directory (in this case, named venv), and any parent directories that don't exist yet. It also puts a pyvenv.cfg file with a home key that points to the installation of Python from where the command was run.

Activate

source venv/bin/activate

You will see the prompt change to display (venv) at the beginning of the line: 

(venv) Username@Computer myfolder %

Use

Install dependencies within the new Python virtual environment, using pip, the default package manager for Unix-like systems such as Mac OS and Linux. Swap out the {packagename} for the package you want to install. 

pip install {packagename}

Deactivate

To stop it, type: 

deactivate

Close

Simply type 

exit

Remove

To remove a Python virtual environment, first deactivate it. Then you can use rm to remove it. 

rm -r venv

A more thorough method is to specify removal of the files and folders made when the environment was created. In the folder where the venv is, run 

rm -r bin include lib lib64 pyvenv.cfg share
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