Today I discovered that you can run the previous command without typing the whole command again. For example if you had to type a long command, in my case it was a docker command.

Something like this -

docker run -p 8080:80 -d --name {conatiner-name} {image-name}

But, I needed a sudo, so instead of typing

sudo docker run -p 8080:80 -d --name {conatiner-name} {image-name}

we can do this sudo !!

the !! will recall the last entered command in the shell and execute.