lpsched and 'default destination'

[Mark J Elkins]

This is a really wild story about the Line Printer Schedular on SCO
Xenix 2.3.2.

My customer, lp has worked fine for months - spooling to two different
printers, one parallel (Called 'C0') and one serial (called 'C1').
C0 is also the default destination.  All of a sudden - C0 stops - and
refuses to work.

Items queue up properly - but only 'C1' works.  Leaving messages in
the interface file does nothing, the interface is never run.  Direct
printing (cat file >/dev/lp) however works!  Eventually - I create a
3rd (dummy) printer - and make it the default.  Now both printers
work!  - though the dummy just collects jobs (It can't even print to
/dev/null and the 'interface' is the line 'exit 0' ????).  I assume
that lpsched has been hit by a cosmic ray and re-install 'lpr'.  I
also do 'cmp's on the old and new.  Absolutly no difference.

On re-installing the two prointers, I do NOT set up a default - and
everything works fine.  I edit the file 'default' first to one then
the other printer - and which ever is default refuses to print!
(Stuff queued up on the previous 'default' always prints again.)

Problem - customer _needs_ a default printer.  Solution - No default
in the default file - but the lines 'LPDEST=C0; export LPDEST' in
/etc/profile 'covers up' the problem and the customer is happy.

But I'm confused!  What is going on?  Why does lpsched seem to examine
the 'default' printer - even after stuff is queued for the 'default'
printer - but ONLY if the default is in /usr/spool/lp/default ????

-- 
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