[conspire] HP LaserJet4 - CUPS lists printer twice

[Rick Moen]

Quoting Darlene Wallach (freepalestin at dslextreme.com):

> I picked up the HP LaserJet4 printer from Bruce today. Since it has a
> parallel port, I connected it to my desktop VA Linux 420. 
> I am using CUPS to add it so I can print. The "List Available
> Printers" lists it twice:
> 
> - add this printer HP LaserJet 4 Plus (HP LaserJet 4 Plus LPT #1)
> - add this printer HP LaserJet 4 Plus (HP LaserJet 4 Plus LPT parport0 HPLIP)
> 
> Why is it listed twice?
> Which one should I add? Does it make a difference?

1.  Insufficient data.  For one thing, you didn't really identify where
in the process you are, including how you got there.  You might, for
example, have done this:

o  Open Web browser to http://localhost:631 (which brings up the CUPS
   administrative Web pages on a Linux machine that has CUPS installed).
o  Select "Add Printer".  Fill in stuff for Name, Location, Description.
   Select Continue.
o  In the Device for Test screen, pick "LPT #1", then Continue.
o  In the Make/Manufacturer for Test scren, pick "HP", then Continue.
o  Scroll down the displayed list of HP printers until one reaches the
   HP LaserJet 4 entries.

2.  However, the two entries you describe are not for a LaserJet 4, but
    rather for a LaserJet 4 Plus.  Wrong printer.

3.  Which entries you see depends on what packages of printer filters
    ("drivers") you have installed.  For example, the Debian box in
    front of me offers (among others) these entries, because it has 
    Gutenprint and Foomatic driver sets installed, along with the
    generic Postscript driver:

    HP LaserJet 4 - CUPS+Gutenprint v5.0.2 (en)
    HP LaserJet 4 Plus - CUPS+Gutenprint v5.0.2 (en)
    HP LaserJet 4 Plus - Foomatic/hpijs (en)
    HP LaserJet 4 Plus v2013.111 Postscript (recommended) (en)
    HP LaserJet 4/4M 600DPI Poscript (recommended) (en)

Picking one of those entries at the end of the process described in item
#1 (above) would result in adding a new entry to /etc/cups/printers.conf
(and /etc/cups/ppd/) saying which filter to use (e.g., hpijs, Generic
PostScript, gutenprint, hplip, gimp-print...), via what means of
communication to reach the printer, etc.  The choice of filter gets
written to one of CUPS's PPD (printer description) files in
/etc/cups/ppd/.

Note that you can also, on the "Make/Manufacturer for test" screen,
pick the option "Or Provide a PPD File".  By happy coincidence, the
top-recommended filter for HP LaserJet 4 printers on OpenPrinting's
page about that printer
(http://www.openprinting.org/show_printer.cgi?recnum=HP-LaserJet_4)
offers download of the HPLIP driver directly, if you prefer.  

HPIJS has been merged into HPLIP, I hear, so the "Foomatic/hpijs" entry
I mention above is probably exactly that.  OpenPrinting says:  "For
basic printing functionality use the Postscript PPD. For advanced
functionality such as printer status and maintenance features, use the
HPLIP driver (which includes HPIJS)."

'Hope that helps.