How to define a function that handles `command not found`?

Question

I'd like to define a function that is called, whenever a shell-user types a command that does not exist. In my case I'd like to log the errors and try alternative commands.

currently, when typing e.g. dgfgsdjagfghsdg the error zsh: command not found: dgfgsdjagfghsdg is shown.

Is there a way to define a function, that get the typed command (+ arguments) as a parameter?

Answer 1

Yes.

• In the Z shell it is a function named command_not_found_handler.
• In the Bourne Again shell it is a function named command_not_found_handle.

Further reading

• Intercept "command not found" error in zsh
• how to locally redefine 'command_not_found_handle'?
• (2x) zsh: command not found
• No command 'bla' found, did you mean:?

Answer 2

To complement JdeBP's answer, in the fish shell it's called fish_command_not_found.