One of Unix's oldest and most persistent design rules is that when a program has nothing interesting or surprising to say, it should shut up . Well-behaved Unix programs do their jobs unobtrusively, with a minimum of fuss and bother. Silence is golden.
This “silence is golden” rule evolved originally because Unix predates video displays. On the slow printing terminals of 1969, each line of unnecessary output was a serious drain on the user's time. That constraint is gone, but excellent reasons for terseness remain.
I think that the terseness of Unix programs is a central feature of the style. When your program's output becomes another's input, it should be easy to pick out the needed bits. And for people it is a human-factors necessity — important information should not be mixed in with verbosity about internal program behavior. If all displayed information is important, important information is easy to find.
Well-designed programs treat the user's attention and concentration as a precious and limited resource, only to be claimed when necessary.
(We'll discuss the Rule of Silence and the reasons for it in more detail at the end of Chapter11.)
