[greentarch]

You can do this, too (untested, but compiles):

pawn Code:

public OnPlayerCommandPerformed( playerid, cmdtext[ ], success )
    return ( !success ) ? ( SendClientMessage( playerid, -1, ">> That command doesn't exist! (/cmds)" ), 1 ) : ( 1 );

Anyways, my suggestion is, rename the topic (ask a moderator) to OnPlayerCommandPerformed tutorial, and add everything you know, like:
>> Player must spawn before using any commands
>> Player must be logged in before using any commands
>> etcetera.