INTRO(1) INTRO(1) NAME intro - introduction to commands DESCRIPTION This section describes publicly accessible commands in alphabetic order. Certain distinctions of purpose are made in the headings: (1) Commands of general utility. (1C) Commands for communication with other systems. (1G) Commands used primarily for graphics and computer-aided design. (1M) Commands used primarily for system maintenance. The word `local' at the foot of a page means that the command is not intended for general distribution. SEE ALSO DIAGNOSTICS Section (6) for computer games. How to get started, in the Introduction. DIAGNOSTICS Upon termination each command returns two bytes of status, one supplied by the system giving the cause for termination, and (in the case of `normal' termination) one supplied by the program, see wait and exit(2). The former byte is 0 for normal termination, the latter is customarily 0 for success- ful execution, nonzero to indicate troubles such as erro- neous parameters, bad or inaccessible data, or other inabil- ity to cope with the task at hand. It is called variously `exit code', `exit status' or `return code', and is described only where special conventions are involved.