Imagine a script is running in these 2 sets of "conditions":

live action, set up in sudo crontab
debug, when I run it from console ./my-script.py

What I'd like to achieve is an automatic detection of "debug mode", without me specifying an argument (e.g. --debug) for the script.
Is there a convention about how to do this? Is there a variable that can tell me who the script owner is? Whether script has a console at stdout?  Run a ps | grep to determine that?
Thank you for your time.
Use a command line option that only cron will use.
Or a symlink to give the script a different name when called by cron. You can then use sys.argv[0]to distinguish between the two ways to call the script.
Detect if python script is run from console or by crontab