Christopher Juckins

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Python Virtual Environments

Overview to conda environments

Installing miniconda

  • Download and install miniconda3 as non-admin user from
  • Get the "Miniconda3 Linux 64-bit" version
  • NOTE: You may need to remove a $HOME/.condarc file if you have one to prevent repo source conflicts
cd $HOME
mkdir $HOME/tmpconda
TMPDIR=$HOME/tmpconda bash
  • (Accept license agreement and all the suggested default choices)
  • Note that if you do not want conda's base environment to be activated upon startup, run the following:
conda config --set auto_activate_base false

Now try creating a test conda environment:

cd ~/miniconda3/envs
~/miniconda3/bin/conda create -n testenv2_3.11.4 -c conda-forge time numpy requests pygrib netCDF4 scipy python=3.11.4
~/miniconda3/bin/conda init bash
  • (Open a new xterm and type 'bash')
conda activate $HOME/miniconda3/envs/testenv
cd $HOME/miniconda3/envs/testenv
  • (do work)
conda deactivate

Other useful commmands (see for specific python versions) :

conda create -n testenv2 python=3.11.3
conda activate testenv2

conda update conda (update just the conda package)
conda update --all (update all conda packages)
python3 -m pip list --outdated
python3 -m pip install --upgrade <package_name>

conda install conda=23.3.1 (installing or force-installing a specific conda package version)

conda -V (the conda version)

conda remove --name myenv --all (remove a conda environment)

Running a cron under conda (is this correct?)

21 15 * * * conda activate testenv2; /path/to/ > /tmp/output.txt (just call the correct version of python in first line of the script)


  • Create a conda test env with specific version of python
  • Run a script using that new test environment
    • Update the first line to point to the correct version of python
  • Run cron under conda
    • If you update the first line in the script to point to desired conda version of python, then no need to activate the conda env (?)

Using venv to set up a python virtual environment

Note: This method does not allow for running a different version of python that is natively installed on the system.

python3 -m venv venv_test
source venv_test/bin/activate
cd venv_test
pip list
pip install --upgrade pip
pip install pygrib

(venv_test) (base) [user@host: ~/venv_test]$ pip list
Package    Version
---------- ---------
certifi    2022.6.15
numpy      1.21.6
pip        22.1.2
pygrib     2.1.4
pyproj     3.2.1
setuptools 40.6.2

When done working:


Setting up a python virtual environment (with virtualenv)

Note: This method does allow for running a different version of python that is natively installed on the system.

dnf install virtualenv
virtualenv --python="/usr/local/bin/python" "/path/to/the/venv_dir/"
cd /path/to/the/venv_dir
source bin/activate

See Python Alternative Upgrade Notes for installing a different/local version of python.

python_virtual_environments.txt · Last modified: 2023/08/10 11:35 by juckins