Open-Source Python Lesson #7 introduces file input and output. After learning exceptions in Lesson #6, the next practical step is saving information to disk and reading it back.

Open a file safely

Python’s with statement is a clean way to work with files because the file is closed when the block finishes.

with open("notes.txt", "w", encoding="utf-8") as file:
    file.write("Hello from Python!\n")

Read the file

with open("notes.txt", "r", encoding="utf-8") as file:
    text = file.read()

print(text)

The mode r reads a file. The mode w writes a file and replaces existing contents. The mode a appends new information to the end.

Append another line

with open("notes.txt", "a", encoding="utf-8") as file:
    file.write("Second line\n")

Technician exercise

Create a small equipment log. Write a device name and status to equipment.txt, append a second device, then read the entire file and print it. This same basic pattern can later support logs, configuration files, test results, and automation scripts.

Video reference

Key takeaway

Use with open(...) to manage a file, choose the correct mode for reading or writing, and keep the first programs small enough that you can inspect the resulting file yourself.