INTRO(1) UNIX Programmer's Manual 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. N.B.: Commands related to system maintenance used to appear in section 1 manual pages and were distinguished by (1M) at the top of the page. These manual pages now appear in sec- tion 8. SEE ALSO Section (6) for computer games. _H_o_w _t_o _g_e_t _s_t_a_r_t_e_d, 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 _w_a_i_t and _e_x_i_t(2). The former byte is 0 for normal termination, the latter is customarily 0 for success- ful execution, nonzero to indicate troubles such as errone- ous 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 special conventions are involved. Printed 11/26/99 April 29, 1985 1