Why do people write #!/usr/bin/env python on the first line of a Python script?

Question

It seems to me like the files run the same without that line.

Answer 1

Perhaps your question is in this sense:

If you want to use: $python myscript.py

You don't need that line at all. The system will call python and then python interpreter will run your script.

But if you intend to use: $./myscript.py

Calling it directly like a normal program or bash script, you need write that line to specify to the system which program use to run it, (and also make it executable with chmod 755)