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. 

N.B.: Commands that relate to system maintenance, distinguished by (1M) are described in section 8. 

Manual pages that describe 4.1bsd UNIX commands are distinguished by the text 4th Berkeley Distribution appearing at the foot of each page. 

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 successful execution, nonzero to 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 special conventions are involved.