This is activated whenever you send a line of input to either a channel or a query user. This means that if you type in a message and hit return, ON INPUT can be activated. ON INPUT can catch and process any input line.
Note: The fact that you can capture any line and suppress further normal processing means you can completely disable the client by accident or on purpose. Don't use this function if you don't know exactly what you are trying to do. Parameters are:
$0 Text of line
If you use ^ to suppress the processing of the line, you can
do your own pre-processing and send the line back to the client
with a call to sendline.
Note $[1]0 is the first character of the first word of the line.
Also, the $T var can show you who or what you're talking to at
any given moment.
See Also: set/input_protection alias/special