less: Page Through Files

cat shows a whole file at once; head and tail show the ends. But what if you want to scroll through a long file at your own pace, up and down?

That is the job of less.

less bigfile.log

less opens the file in a viewer. It does not dump everything. It shows one screenful and waits for you. Inside the viewer you can:

The most important key is q: that is how you leave less and get your shell back.

Why "less"?

There was an older tool called more that could only page forwards. less does everything more does and lets you scroll backwards, hence the joke name: "less is more".

less never changes the file. It is a pure viewer.

In this training sandbox the scrolling viewer is limited, so practise the idea with cat, but on a real Linux system, reach for less whenever a file is too long for one screen.

Mission: Review and Archive the Operations Manual

The station's operations manual has been updated and saved to manual.txt. You need to review it and keep a copy on file. (On a real system you would scroll through it page by page; in this sandbox the scrolling viewer is limited, so display the file instead.)

1. Display the whole manual to review its chapters.
2. Count how many lines the manual has.
3. Create a folder called manuals and copy manual.txt into it as manual-archive.txt.
4. Confirm the archived copy by displaying its contents.

Expected result

The full manual appears, you learn its line count, and the manuals folder holds a faithful copy of it.