An editor that works under pressure

02Read the save destination

Open a named file with nano followed by its path. For a new file, the name chooses a future save location; it does not prove a file has already been written. Keep the destination inside your fresh exercise directory.

Nano displays keyboard shortcuts near the bottom. The notation ^O means hold Ctrl while pressing O; do not type a caret and O into the text. With default bindings, Ctrl+O opens Write Out, which asks where to save. Confirm the intended filename with Enter. Ctrl+X exits.

If you exit after unsaved changes, read any save decision carefully. Choosing not to save discards those buffer changes; cancelling returns to review. This lesson assumes no automatic save or recovery. After a confirmed write, cat lets you inspect the saved content independently of the editor display.

nano demo.txt

editing buffer before typing: unspecified

prior bytes unknown

not yet read

03Use a fresh owned workspace

The paths lesson introduced ~/yanosec-lab: ~ expands to your home directory. Before a file activity, return with cd ~/yanosec-lab. Use pwd to check your location and ls -a to inspect names. Continue only if this is your recognized owned lab. Then create the lesson's new child directory.

If mkdir reports that a destination already exists, preserve that work. Choose an unused name and use it consistently, or follow the paper route. Enter one command at a time and continue only after the preceding step succeeds. Record an unexpected result before doing anything else.

Unless the lesson says otherwise, leave the small activity folder for review and return with cd ~/yanosec-lab when finished. Closing the terminal does not delete files you saved. These activities need no sudo or system-file changes.

04Try a saved note

The worked file uses first draft. The activity uses meeting at ten, so you can tell the two cases apart. Both are harmless text; neither requires a privileged editor or a system-file change.

The worksheet retains an earlier Nano 7.2 observation: pressing Enter before Write Out saved the sentence with a blank second line. This is a recorded result from the earlier exercise, not a claim about every editor setting. In the paper route, trace open, edit, write, exit and read-back using that record. Running Nano can wait if it is unavailable.

first draft

Trace editing and saving separately

A buffer is the text being edited in memory. Write Out saves it to a
named file. After exiting, reading that file checks stored bytes.
The Nano 7.2 observation below is retained from the earlier course
exercise record; it is not a newly performed session or a guarantee
about every configuration.

Nano 7.2 in a disposable directory. This card is the keystroke record, not a screenshot.
nano note.txt
Type exactly: meeting at ten, then press Enter once.
Ctrl+O: write out; confirm note.txt with Enter; Ctrl+X: exit.
Observed with Nano 7.2: the first line is meeting at ten, and a blank second line is also present.
^O on screen means hold Ctrl while pressing O, not type caret and O.
If a prompt offers to save unexpected changes, read filename and decision;
cancel and preserve work if uncertain. Do not edit host/system files.
Question: buffer changed; exit without saving; no autosave/recovery assumed.
Does disk necessarily hold the new buffer content? yes/no

1. At the lab root create mkdir editor, then cd editor after success. Check that note.txt does not already exist before opening nano note.txt.
2. Type meeting at ten and press Enter once. Locate the displayed Write Out and Exit shortcuts; do not paste the prompt labels as file content.
3. Press Ctrl+O, confirm note.txt with Enter, then Ctrl+X. If any filename or save decision differs, cancel the decision and inspect it rather than agreeing blindly.
4. Read cat note.txt outside Nano. Expected with Nano 7.2: the first line is meeting at ten, and pressing Enter before Write Out also leaves a blank second line. Record actual content and path; a screenshot of a buffer alone would not prove the save.
5. On paper trace open, buffer change, write and read-back using the same text. Label live editing deferred. Return to the lab root and retain the file; no system edits or cleanup are needed.

05Optional challenge

Allow about ten extra minutes. Start from a saved first draft, change the buffer on paper, and choose exit without saving. Track the buffer and disk file separately. Explain why reopening cannot be assumed to restore an unsaved change through an unspecified recovery feature.

06Fresh cases for the checks

Use these fictional cases for the checks below. They have different inputs from the worked examples. Read them here or make notes; no installation or external service is needed.

Starting disk file plan.txt contains: gate closes at six
No file copy.txt exists initially.
1. Open plan.txt and change the buffer to: gate closes at eight
2. Write Out that buffer to copy.txt and confirm that write.
3. Change the buffer again to: gate closes at nine
4. Exit and choose not to save this last change.
No other write, automatic save or recovery occurs. Read only the first-line text.

A learner wants to save an owned note in Nano with its default bindings.
Nano displays ^O for Write Out.
The learner types the two characters ^O into the buffer instead.
No Write Out prompt appears. No save has occurred.

Intended first line in the file ./travel/packing.txt: bring spare socks
The editor buffer shows: bring spare socks
A confirmed Write Out saved to ./travel/packing-copy.txt.
After exit, cat ./travel/packing.txt displays: bring socks
Both paths belong to this exercise. No automatic save or synchronization is present.

Starting first line on disk in reminder.txt: return before noon
Open reminder.txt; change its buffer to: return before dusk
Confirm Write Out to reminder.txt, then exit.
No later changes occur. Predict only the first-line text, excluding its newline.

07Explain what proves a save

Optional self-check: explain how you would preserve an edited note and check the saved result. Include the buffer, the Write Out filename, the shortcut and a read-back after leaving the editor.

Review your explanation: interpret ^O as a Ctrl key combination; inspect the destination before confirming; distinguish a buffer edit from a disk write; and compare the intended content with the same saved path. Name any editing work you have only traced on paper. This explanation is self-reviewed.