Django in python3 on mac os

ummm ... Since I always install django using virtualenv, I'm not familiar at all with installing django via pip3 as system site-packages.

Off the top of my head, I can think of couple of causes for command not found error.

Run the following command in your terminal

python3 -c "import django; print(django.get_version())"

It should return Django version number; if however it returns an ImportError: No module named 'django', that means Django wasn't installed correctly, maybe you should try install it again.

Once you've confirmed that Django is indeed installed properly; another cause for command not found error is that the django_admin executable isn't on your System Path. However, I do believe that a successful Django installation would place django_admin in your Mac's system path; maybe you just need to re-source/reload your terminal's profile. It can be done by entering this command

source ~/.bash_profile

But I think the easiest way to achieve that is simply restart the Terminal. So try that, see if it fixes the issue.