Editing the Current Line (nano)
Let us assume we want to type the command ls -ld /etc but typed ls -l /etc.
Since we are well acquainted with nano shortcut keys lets edit the line using nano.
The key sequence C-x + M-e opens the nano browser with the contents of the Readline buffer. The cursor is positioned at the beginning of the line.
Use the key sequence Ctrl +F to start a forward search then use the key sequence l <enter> to search from the current cursor position to the next occurence of the letter l.
In this case it is easier to use the right arrow to move the cursor forward one character and enter the letter d. If you were going to replace more than one character you would use the key sequence Alt+R to start replace session.
Next use the key sequences Ctrl +O <enter> to write out the edited command and then Ctrl + x to exit nano. Once you exit nano the command will execute.
These examples are deliberately simple so you can focus on how the external‑editor feature works. Once you’re comfortable with the basic flow, you can use your editor to handle much more involved changes—multi‑line commands, long pipelines, or anything else you’d normally edit in a text file. The important part is that Readline hands the entire command line to your editor, and whatever you write out becomes the command that runs.