Specifying input and output file names in the Terminal

So far, you have specified the file names directly inside the program. Alternatively, it is possible to write your program so that you can specify the names of the input and output files in the Terminal when the program is run. This is particularly useful if you need to run the same program several times with different input datasets and collect several different output files.

The sys module allows you to access an array of strings that correspond to the parameters entered in the Terminal when a program is run. To get a sense for how this works, you can use create a basic program as follows to import the sys module and print out the parameter array:

import sys
print(sys.argv)

You can specify parameters to the program after the initial Python command separated by spaces, as follows:

$Python(3) json_code.py arg1 arg2 asdf fdsa

When running the preceding command, you will see that the parameters that you specified become the elements of the...