replacing last command and execute it

For example

$ echo "hello world world world"
hello world world world

If you want to replace world with universe you can do

# If you use ZSH you can press `tab` at the end of the line and it will replace
# the whole line with the actuall command
$ ^world^universe
$ echo "hello universe world world"

As you can see, it only replace the first matching word.

If you want it to replace the whole match:

# zsh
$ ^world^universe^:G
# bash

Don't use it in production I tend to use fc command which allow me to edit the command in my editor first