Python shebang with conda
Question:
Following best practice I have started an executable Python script with a shebang specific to Python 3:
#!/usr/bin/env python3
import spotipy
# ...some fancy code
One chmod +x later, I’m executing this script as ./quick_example.py but alas the executable found (running locally on my Mac) is not the Python executable in my active Conda environment, as running which python3 in my Bash shell throws up /usr/bin/python3 instead of the desired /Users/anilkeshwani/opt/miniconda3/envs/spot/bin/python given by which python.
Apparently using #!/usr/bin/env python is bad practice in general, so my question is: can I keep the Python 3-specific shebang and somehow have Conda alias python3 calls when an env is active?
Answers:
So, I’m not sure what you’ve read. Unfortunately, the naming convention across *nix platforms is a total mess. IMO, python should just always be Python 3, since Python 2 is passed the EOL. But this is above my pay grade. In any case, looking at PEP 394:
For scripts that are only expected to be run in an activated virtual
environment, shebang lines can be written as #!/usr/bin/env python, as
this instructs the script to respect the active virtual environment.
It gets messy for scripts not expected to be run in a virtual environment.
TL:DR
Just use #!/usr/bin/env python
Edit
Ah, looking at the answer you linked to, they were referencing and old version of PEP 394 which has been revised several times since that answer was posted. A total mess, unfortunately.
Noting the answer by juanpa, I think your problem may be in that you haven’t activated your conda environment in the shell in which you are running ./quick_example.py.
Activating a conda environment is done by running source activate <envname>. Just creating the env isn’t enough, you have to activate it as well before it takes effect. This has to be done each time you create a new shell, although IDEs often have ways to have this be done automatically.
Following best practice I have started an executable Python script with a shebang specific to Python 3:
#!/usr/bin/env python3
import spotipy
# ...some fancy code
One chmod +x later, I’m executing this script as ./quick_example.py but alas the executable found (running locally on my Mac) is not the Python executable in my active Conda environment, as running which python3 in my Bash shell throws up /usr/bin/python3 instead of the desired /Users/anilkeshwani/opt/miniconda3/envs/spot/bin/python given by which python.
Apparently using #!/usr/bin/env python is bad practice in general, so my question is: can I keep the Python 3-specific shebang and somehow have Conda alias python3 calls when an env is active?
So, I’m not sure what you’ve read. Unfortunately, the naming convention across *nix platforms is a total mess. IMO, python should just always be Python 3, since Python 2 is passed the EOL. But this is above my pay grade. In any case, looking at PEP 394:
For scripts that are only expected to be run in an activated virtual
environment, shebang lines can be written as#!/usr/bin/env python, as
this instructs the script to respect the active virtual environment.
It gets messy for scripts not expected to be run in a virtual environment.
TL:DR
Just use #!/usr/bin/env python
Edit
Ah, looking at the answer you linked to, they were referencing and old version of PEP 394 which has been revised several times since that answer was posted. A total mess, unfortunately.
Noting the answer by juanpa, I think your problem may be in that you haven’t activated your conda environment in the shell in which you are running ./quick_example.py.
Activating a conda environment is done by running source activate <envname>. Just creating the env isn’t enough, you have to activate it as well before it takes effect. This has to be done each time you create a new shell, although IDEs often have ways to have this be done automatically.