{"id":42,"is_content":1,"post_type":"post","post_title":"Change python version only in a single virtual environment","slug":"change-python-version-only-in-a-single-virtual-environment","source_value":"https:\/\/askubuntu.com\/questions\/1390269\/change-python-version-only-in-a-single-virtual-environment","fake_user_id":43208,"published_at":"2021-09-29T22:08:23.000000Z","view_count":0,"deleted_at":null,"created_at":"2022-02-01T10:08:31.000000Z","updated_at":"2023-02-01T08:38:46.000000Z","content":[{"id":9110354,"post_id":42,"fake_user_id":85237,"content_dec":"<div class=\"s-prose js-post-body\" itemprop=\"text\">&#xD;\n                &#xD;\n<p>Gnome terminal will only run when <code>python3.6<\/code> is used. So I created an environment and installed <code>python3.9<\/code> like so:<\/p>\n<pre><code>#!\/usr\/bin\/env bash\n\nsudo apt install python3-venv\npython3 -m venv test_env\nsource test_env\/bin\/activate\n\nsudo add-apt-repository ppa:deadsnakes\/ppa\nsudo apt-get update\napt list | grep python3.9\nsudo apt-get install python3.9\nsudo update-alternatives --install \/usr\/bin\/python3 python3 \/usr\/bin\/python3.6 1\nsudo update-alternatives --install \/usr\/bin\/python3 python3 \/usr\/bin\/python3.9 2\nsudo update-alternatives --config python3\npython3 -V\n<\/code><\/pre>\n<p>However this causes the whole system to switch to <code>python3.9<\/code> and prevents terminal from working. How can I prevent this?<\/p>\n<p>Now, running <code>source ~\/.bashrc<\/code> allows the non-venv terminal to continue working. And <code>python -V<\/code> reports the correct version of <code>3.6<\/code>. But if I close the window I can't reopen it. I have to use a terminal in my IDE to reselect the older version of python. Running:<\/p>\n<pre><code>sudo update-alternatives --install \/usr\/bin\/python3 python3\n<\/code><\/pre>\n<p>Shows that actually, version <code>3.9<\/code> is selected. Even though <code>python -V<\/code> actuallt reports running <code>python3.6<\/code>:<\/p>\n<pre><code># Python 3.6.9\n\n\n#  Selection    Path                 Priority   Status\n# ------------------------------------------------------------\n#  0            \/usr\/bin\/python3.9    2         auto mode\n#  1            \/usr\/bin\/python3.10   2         manual mode\n#  2            \/usr\/bin\/python3.6    1         manual mode\n#* 3            \/usr\/bin\/python3.9    2         manual mode\n<\/code><\/pre>\n    <\/div>","created_at":"2023-02-01T08:38:46.000000Z","updated_at":"2023-02-01T08:38:46.000000Z"},{"id":9110355,"post_id":42,"fake_user_id":54218,"content_dec":"<div class=\"s-prose js-post-body\" itemprop=\"text\">&#xD;\n<p>As outlined by Vanadium, using <code>PPA<\/code> updates the system version of python. So even from the venv I was making a global change.<\/p>\n<p>The solution is quite obvious; Python3 doesn't run Python3, it runs whatever version of python3 is installed on the system, so in my case...<\/p>\n<pre><code>python3 -m venv test_env\n<\/code><\/pre>\n<p>Was setting up a python3.6 venv. Running...<\/p>\n<pre><code>python3.9 -m venv test_env\n<\/code><\/pre>\n<p>Appears to have correctly setup a python3.9 venv. To hammer home the point, in order to run python code in ATOM IDE using Hydrogen, in my 3.9 venv I had to run...<\/p>\n<pre><code>python3.9 -m ipykernel install --user --name=atom_venv_py\n<\/code><\/pre>\n<p>So it's just a case of specifying which version of python you want to use in every instance where it deviates from the sys version (IPython kernel is the Python execution backend for Jupyter which allows Hyrdogen to run).<\/p>\n    <\/div>","created_at":"2023-02-01T08:38:46.000000Z","updated_at":"2023-02-01T08:38:46.000000Z"}],"tags":[{"id":88,"slug":"18-04","name":"18.04","suggest":0,"count":15162,"tag_group_id":null,"description":null},{"id":6,"slug":"bash","name":"Bash","suggest":0,"count":10209,"tag_group_id":null,"description":null},{"id":82,"slug":"gnome","name":"Gnome","suggest":0,"count":9966,"tag_group_id":null,"description":null},{"id":77,"slug":"python3","name":"Python3","suggest":0,"count":1279,"tag_group_id":null,"description":null}],"tagged":[{"id":118,"taggable_id":42,"taggable_type":"App\\Models\\Post","tag_name":"18.04","tag_slug":"18-04","tag":{"id":88,"slug":"18-04","name":"18.04","suggest":0,"count":15162,"tag_group_id":null,"description":null}},{"id":119,"taggable_id":42,"taggable_type":"App\\Models\\Post","tag_name":"Bash","tag_slug":"bash","tag":{"id":6,"slug":"bash","name":"Bash","suggest":0,"count":10209,"tag_group_id":null,"description":null}},{"id":120,"taggable_id":42,"taggable_type":"App\\Models\\Post","tag_name":"Gnome","tag_slug":"gnome","tag":{"id":82,"slug":"gnome","name":"Gnome","suggest":0,"count":9966,"tag_group_id":null,"description":null}},{"id":121,"taggable_id":42,"taggable_type":"App\\Models\\Post","tag_name":"Python3","tag_slug":"python3","tag":{"id":77,"slug":"python3","name":"Python3","suggest":0,"count":1279,"tag_group_id":null,"description":null}}]}