If we want the welcome message to greet us by name no matter whether we supply the argument to the script or not, we can add in a prompt to capture the data while the script is running. Python makes this simple and easy to implement. We can see from the edited file shown in the screenshot that follows how this is achieved:
We make use of a new variable in the script that we set in the main block initially, to be an empty string. Set it here to make the variable available to the complete script and all code blocks.
The input function in Python 3 or raw_input can be used in Python 2 to gain user input. We store that input in the name variable. If we have supplied an argument we pick it up on the code in the else block and set the name variable to the first supplied argument. It is this that is used in the print statement back in the main block.
To add some variety to this chapter, we will now look at printing this data to a file. Again using Python, this is quite a simple and easy way to pick up. We will start by making a copy of our existing args.py. We will copy this to $HOME/bin/file.py. The new file.py should read similar to the following screenshot and have the execute permission set:
You will notice that we have just altered the final lines and instead of print we now open a file. We also see more of the object-orientated life of Python that dynamically assigns the write() and close() methods to the object log, as it is seen as an instance of a file. When we open the file, we open it up for the purpose of appending, meaning that we do not overwrite the existing content if it is already there. If the file is not there, we will create a new file. If we use w, we will open the file for writing, which might translate to overwriting, so take care.
You can see that this is an easy task and this is why Python is used in many applications and is taught widely in schools.