How does man know?

[John Hood]

In article <11211 at smoke.BRL.MIL> gwyn at brl.arpa (Doug Gwyn) writes:
[following up on this considerable thread]
>Actually, *I* said it should be done in the terminal;
>somebody else said it should be done in the terminal handler
>(loosely called the device driver) and explained how theirs worked.
>What we agreed on was that pagination rightfully should be dealt
>with considerably closer to the viewer, who has pagination needs,
>not in the applications that should perform orthogonal functions.

(playing devil's advocate here)

I can respect Doug's position; it has validity.  But this argument is
beginning to sound a bit like the question of "where do we put
command-line editing/history?"  If we put it in the kernel, a la the
BSD tty driver, then you get the feature everywhere, but you may not
be able to implement it well or properly for all cases, and the user
will find it difficult to replace the feature with one they like.  If
you make it a user-level process, then it is much easier to change or
enhance or remove.  Look at the features of 'less', which would be
impossible for a terminal driver or intelligent terminals.  Of course,
a user-level pager will not work right in all cases either.

Consider these two situations:

1) more's output being fed to a printer /dev/lp0

2) A smart terminal or driver monitoring the considerable, but slow,
output of tail watching some process or sar or vmstat in a background
window

Another facet to this issue is that man is one of the few programs
that automatically pipes output through a pager.

  --jh-- 
John Hood, Biar Games snail: 10 Spruce Lane, Ithaca NY 14850
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