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Repair: Files, Folders and Applications

Mental model​

A file holds data; a folder organizes names pointing to files and other folders. A filename extension such as .txt is a convention that helps applications choose how to open it. Renaming an extension does not convert the data inside. A browser displays web content; an editor changes source or plain text; a terminal presents a command interface. Saving changes the file on disk. Typing unsaved changes into an editor does not change what another process reads from disk.

Guided practice​

  1. Create a new disposable launchpad-practice folder using your file manager. Inside it create notes.
  2. Use a plain-text editor to save session.txt inside notes. Enable filename-extension display or inspect the file properties so you can detect names such as session.txt.txt.
  3. Close and reopen the file. Confirm that it contains your intended text. If it does not, check the save location and whether the editor used rich text.
  4. Duplicate the file as session-backup.txt. Edit the duplicate, save it and reopen both. A normal copy has independent contents; a shortcut or alias points to another location instead.
  5. Move the duplicate into a new archive folder. Find it again using the folder hierarchy. Do not practise on valuable documents.

Paths without memorized commands​

Imagine a folder named course, containing notes, containing session.txt. From course, the relative path is notes/session.txt. From inside notes, it is session.txt. A full path starts from a filesystem root and identifies the location independently of your current folder. Path notation varies across operating systems; the relationship between folders is the same.

When a tool cannot find a file, check three things: current folder, exact filename and extension, and whether the file was saved. Do this before reinstalling the tool.

Check yourself​

Why does changing session.txt to session.pdf not create a PDF? Why can a file be visible in an editor but absent from the folder you expected? Explain using data format and save location.

Repeat A1–A4 from the fresh reassessment without a walkthrough. Then continue Developer Environment and Tooling; its terminal lessons build on this model.

Reference: Missing Semester shell introduction, specifically working directories and paths. It is a later command-line companion, not a prerequisite for the graphical exercises above.