Command Line@python

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The CPython interpreter scans the command line and the environment for various settings.

CPython implementation details: Other implementations' command line schemes may differ.

Command Line

When invoking Python, you may specify any of these options:

python [-bBdEhiIOqsSuvVWx?] [-c command | -m module-name | script | -] [args]

The most common use case is, of course, a simple invocation of a script:

python myscript.py

Interface options

The interpreter interface resembles that of the UNIX shell, but provides some additional methods of invocation:

• When called with standard input connected to a tty device, it prompts for commands and executes them until an EOF (an end-of file character, you can produce that with Ctrl-D on UNIX or Ctrl-z, Enter on Windows) is read.
• When called with a file name argument or with a file as standard input, it reads and executes a script form that file.
• When called with a firectory name argument, it reads and executes an appropriately named script from that directory.
• When called with -c command, it executes the Python statement(s) given as command. Here command may contain multiple statements separated by newlines. Leading whitespace is significant in Python statements!
• When called with -m module-name, the given module is located on the Python module path and executed as a script.

In non-interactive mode, the entire input is parsed before it is executed.

An intervace option terminates the list of options consumed by the interpreter, all consecutive arguments will end up in sys.argv - note that the first element, subscript zero, is a string reflecting the program's source.

-c : Execute the Python code in command. command can be one or more statements separated by newlines, with significant leading whitespace as in normal module code. NOTE If this option is given, the first element of sys.argv will be "-c" and the current directory will be added to the start of sys.path (allowing modules in that directory to be imported as top level modules).

-m : Search sys.path for the named module and execute its contents as the __main__ module. See also: https://docs.python.org/3/using/cmdline.html#cmdoption-m

-: Read commands from standard input (sys.stdin). If standard input is a terminal, -i is implied. NOTE if this option is given, the first element of sys.argv will be "-" and the current directory will be added to the start of sys.path.