on [<mode>]public_msg [<serial#>] [-|^]<match> { <action> }

This hook is triggered whenever the client receives a public message in a channel from someone not actually in the channel.

To customize how these messages are displayed:

 on ^public_msg "*" {
    if ( [$1] == C ) {
       xecho -b \($0\) $2-
    } {
       xecho -b \($0:$1\) $2-
    }
 }