Scripts are files full of code that has been put together in order to do a particular task. The idea being that the code will get re-run many times and not just as a one off.
Building a script is usually pretty easy - just type the code in to a text file.
You’ll need a text editor, a program that deals with text but not in the same way as a word processor. Many such programs are available, try the options below
Most Python scripts have this on the first line
#!/usr/bin/env pythonThis is a Unix/Linux convention that affects how those systems interpret the file. Leave it in for convention’s sake.
By convention, Python script filess end in the extension, .py.
So if we have the following in a file called hello_world.py, we have a Python script.
#!/usr/bin/env python
print("Hello, World!")
Once created, the script itself is run from the python command on the command line. python is just a regular program that accepts a python script filename as its argument and runs the code in the script.
Here’s an example terminal session that runs a script.
Last login: Thu Dec 6 10:59:32 on ttys000
~/Desktop macleand$ python hello_world.py
Hello, World!
~/Desktop macleand$A good reason for creating scripts is because you want to be able to re-run the code in them. Sometimes you’ll want to change some aspect or behaviour of the code according to settings given on the command-line. For example, you might want to work on a different input file each time. We can access the text from the command-line in the script, using the sys.argv attribute in the sys module.
Imagine the command line
python my_script.py OPTION_1 option_2We access it like this
#!/usr/bin/env python
import sys
print( sys.argv )['/Users/macleand/Desktop/programming_with_python/renv/python/virtualenvs/renv-python-3.8/lib/python3.8/site-packages/ipykernel_launcher.py', '-f', '/private/var/folders/22/kjdvv_k14cj1m6hq5hl527qw0006zc/T/tmpjjcmkkm3.json', '--HistoryManager.hist_file=:memory:']['my_script.py', 'OPTION_1', 'option_2']The sys.argv attribute gives us a list of the command line options. The first item in the list is the script name, the options come after that. So we can access the options by indexing the sys.argv list
python my_script.py OPTION_1 option_2#!/usr/bin/env python
import sys
first_option = sys.argv[1]
second_option = sys.argv[2]
print(second_option, first_option)/private/var/folders/22/kjdvv_k14cj1m6hq5hl527qw0006zc/T/tmpjjcmkkm3.json -foption_2 OPTION_1You said.. <argument> - replacing <argument> with the value you give on the command line.