#!/usr/bin/python3 is a shebang line.
A shebang line defines where the interpreter is located. In this case, the
python3 interpreter is located in
/usr/bin/python3. A shebang line could also be a
perl or any other scripting languages' interpreter, for example:
Without the shebang line, the operating system does not know it's a python script, even if you set the execution flag (
chmod +x script.py) on the script and run it like
./script.py. To make the script run by default in python3, either invoke it as
python3 script.py or set the shebang line.
You can use
#!/usr/bin/env python3 for portability across different systems in case they have the language interpreter installed in different locations.
~ Answered on 2011-10-06 04:35:49