Me in IT UNIX/Linux consultancy

Here is a trick you can use in VI if you need to repeat an action multiple times. Imagine you have this file:

You want to change it to read "Hello world!" Here is what you can do in VI:

1. Go to the first occurrence of what you would like to have changed.
2. Enter "q" to initiate a recording.
3. Enter a letter or digit to save the recording under, like "a" or "1".
4. Do the actions you would like to repeat.
5. Enter "q" again to stop and save the recording.
6. Go to the line where you would like to start running the saved recording/macro.
7. Enter "@" followed by the letter of digit you have saved the recording under, like "a" or "1".

So, now you have learned what this (annoying) "recording" option can be used for!