22.09.2013, 09:01
the tittle says everything..
public OnPlayerCommandPerformed(playerid, cmdtext[], success)//callback from #include <zcmd>
{//open
if(!success)//If the command does not exist on the server, ! = false
return SendClientMessage(playerid, COLOR_WHITE, "Your Error Message Here.");//showing the message
return 1;
}//close
if(!success)
// if it returns 0, send an error message