You can get the previous command that you typed by
pressing the 'up arrow' key on the keyboard.

You can get the even more previous commands that you typed by
pressing the 'up arrow' key repeatedly until you get the one you want.

You can now edit it by moving left and right with the arrows,
and inserting or deleting until it is correct.

Then press ENTER and it shall execute.

Just saves you retyping a long command, particulary useful when
you are developing pipelines, because you can just add the next
bit of the pipeline, execute it to see if it is OK, and then
get back that OK command and add another pipe stage.

Here is a typical sequence:

           $ cat file		[seems to be the file we want]
[up arrow] $ cat file|tr -d '\r'	[delete those MSDOS returns]
[up arrow] $ cat file|tr -d '\r'>save	[save it temporarily]
[up arrow] $ cat file|tr -d '\r'>save;mv save file	[update original]