• Run the anaconda installer for Python 3.x from here.

• In a new terminal, go to the directory conda was installed into (probably, ~/anaconda3 or ~/opt/anaconda3) and run

  condabin/conda $SHELL

• In a new terminal, run

  conda config --set auto_activate_base false

This configures your shell and conda such that if you open a new terminal, the environment is as if conda was never installed except that you can type conda activate ENV_NAME to easily switch to a conda environment.

(More precisely, the above configuration is doing the minimal change to the environment of a new terminal to make conda visible by adding a directory to PATH that contains only the conda command. A new terminal is still picking up the native python in a new terminal until the user explicitly indicates otherwise with conda activate ...).