.TH INTRO 1 .SH NAMEintro \- introduction to commands.SH DESCRIPTIONThis section describes publicly accessible commandsin alphabetic order.Certain distinctions of purpose are made in the headings:.TP(1)Commands of general utility..TP(1C)Commands for communication with other systems..TP(1G)Commands used primarily for graphics and computer-aided design..TP(1M)Commands used primarily for system maintenance..PPThe word `local' at the foot of a page means that thecommand is not intended for general distribution..SH SEE ALSO.SH DIAGNOSTICSSection (6) for computer games..PP.I How to get started,in the Introduction..SH DIAGNOSTICSUpon termination each command returns two bytes of status,one supplied by the system giving the cause fortermination, and (in the case of `normal' termination)one supplied by the program,see.I waitand.IR exit (2).The former byte is 0 for normal termination, the latteris customarily 0 for successful execution, nonzeroto indicate troubles such as erroneous parameters, bad or inaccessible data,or other inability to cope with the task at hand.It is called variously `exit code', `exit status' or`return code', and is described only where specialconventions are involved.