When you are writing or editing a particularly long command line in the shell, you can enter the following key combination and spawn of an editor to assist your.
<ctrl>-x-e
When closing the editor the command line entered is executed.
You can specify what editor to use using two different variables.
$ env | grep -e 'EDITOR\|VISUAL'
EDITOR=/usr/local/bin/vim
VISUAL=code --wait --new-windowThe shell should pick the appropriate one.
An alternative to <ctrl>-x-e is the command fc (fix command) which can do a lot of things, by default takes the last command from your history. Do note that is does not respect $VISUAL and uses $EDITOR, or: $FCEDIT.