How can I get environment variables defined at script launch in python?

Question

I can use os.environ to access variables.

However I would like to distinguish between "pre-defined" variables and variables defined at script launch time.

My use case is the following. Suppose I launch a script like this:

var1="value1" var2="value2" python script.py args

I would like to be able to log the entire command typed in the shell prompt, that is:

• script name
• script arguments
• environment variables defined before the command ( var1 and var2 )

The first two points can be done with sys.argv , but at the moment I cannot distinguish between previously defined variables and var1 and var2 .

Answer 1

It's not fully clear wha are you trying to distinguish. I guess these are your cases:

export var1="value1"
python script.py args
### vs
var1="value1" python script.py args

If I'm correct then it's impossible to do from Python (or really any language). It is a shell feature to set/override environmental variable when running the command, so the process get the full environment as a dictionary (or a hash map if you will), and there's no difference between environment variables by how they've been set.

Answer 2

Why not use os.environ to set the environment variables inside the script?

you can get initial environment variables

for k,v in os.environ.items():
  print(f"{k}={v}")

and then you can set yours:

os.envrion["var1"]=value1
os.envrion["var2"]=value2