psf — PostScript filter
psf is an lpd filter for PostScript printing. psf interprets the name it was called with to determine what filters to invoke. First, if the string ``pap'' appears anywhere in the name, psf invokes pap to talk to a printer via AppleTalk. Next, if the string ``rev'' appears, psf invokes psorder to reverse the pages of the job. Finally, if psf was called with a filter's name as the leading string, it invokes that filter. If there is no filter to run, psf examines the magic number of the input, and if the input is not PostScript, converts it to PostScript.
In the default configuration, psf supports two kludges. The first causes psf to check its name for the letter `m'. If this letter is found and accounting is turned on, psf calls pap twice, once to get an initial page count and to print the job, and another time to get a final page count. This is a work-around for bugs in a variety of PAP implementions that cause printers to never properly close the PAP output file. A notable example is any printer by Hewlett-Packard.
The second kludge causes psf to examine its name
for the letter `w'. If this letter is found and accounting is turned
on, psf calls pap with
the -w flag. This flag causes pap
to wait until the printer's status contains the string `idle'.
Once this string is found, the job is printed as normal. This kludge is a
work-around for printers, notably Hewlett-Packard's LaserJet IV, which
will report a page count while a previous jobs is still printing.
The sample printcap entry below invokes psf to print text files, PostScript files, troff's C/A/T output, and TeX's DVI output, to an AppleTalk connected LaserWriter Plus. Since the LaserWriter Plus stacks pages in descending order, we reverse the pages and print the burst page last.
laser|lp|LaserWriter Plus on AppleTalk:\
:sd=/var/spool/lpd/laser:\
:lp=/var/spool/lpd/laser/null:\
:lf=/var/log/lpd-errs:pw#80:hl:\
:of=ofpap:\
:if=ifpaprev:\
:tf=tfpaprev:\
:df=dfpaprev:
Note that if the host in question spools to more than one AppleTalk
printer, /dev/null should not be used for the
lp capability. Instead, a null device
should be created with mknod for each
printer, as has been done above.
Finally, there is a file in the spool directory,
/var/spool/lpd/laser, called .paprc,
which pap reads for the AppleTalk name of
the printer.
