in a FB 5.5 script I call an external programm that requires username + password as parameter (via "execute programm").
Now, I want to have this action excluded from the log, so that username + pw do not appear in the log (with FB 5.5 Server, all server users could look up this info in the log).
There's a "Suppress Log Messages" option on the Runtime property page of the action. This will omit all of the action's output from the log.
Alternatively, if you don't want to suppress _all_ of the output of the action, then you can use the OnStatusMessage event to modify the output of the action.
(This is assuming your password doesn't contain whitespace, and it prefixed by -P. You'll need to edit it to match the exact specifics of your password syntax. If it contains spaces, then just match everything within two quotes.)
Hth. Please let us know if you need any more assistance.