NAME
lpd - line printer daemon

SYNOPSIS
/usr/lib/lpd [ -l ] [ port # ]

DESCRIPTION
Lpd is the line printer daemon (spool area handler) and is normally
invoked at boot time from the rc(8) file. It makes a single pass
through the printcap(5) file to find out about the existing
printers and prints any files left after a crash. It then uses the
system calls listen(2) and accept(2) to receive requests to print
files in the queue, transfer files to the spooling area, display
the queue, or remove jobs from the queue. In each case, it forks a
child to handle the request so the parent can continue to listen
for more requests. The Internet port number used to rendezvous
with other processes is normally obtained with getservent(3) but
can be changed with the port# argument. The -l flag causes lpd to
log valid requests received from the network. This can be useful
for debugging purposes.

Access control is provided by two means. First, all requests must
come from one of the machines listed in the file /etc/hosts.equiv
or /etc/hosts.lpd. Second, if the "rs" capability is specified
in the printcap entry for the printer being accessed, lpr(1)
requests will only be honored for those users with accounts on the
machine with the printer.

The file minfree in each spool directory contains the number of
disk blocks to leave free so that the line printer queue won’t
completely fill the disk. The minfree file can be edited with your
favorite text editor.

The file lock in each spool directory is used to prevent multiple
daemons from becoming active simultaneously, and to store
information about the daemon process for lpr(1), lpq(1), and
lprm(1). After the daemon has successfully set the lock, it scans
the directory for files beginning with cf. Lines in each cf file
specify files to be printed or non-printing actions to be
performed. Each such line begins with a key character to specify
what to do with the remainder of the line.

J Job Name. String to be used for the job name on the burst
page.

C Classification. String to be used for the classification line
on the burst page.

L Literal. The line contains identification info from the
password file and causes the banner page to be printed.

T Title. String to be used as the title for pr(1).

H Host Name. Name of the machine where lpr(1) was invoked.

P Person. Login name of the person who invoked lpr(1). This is
used to verify ownership by lprm(1).

M Send mail to the specified user when the current print job
completes.

f Formatted File. Name of a file to print which is already
formatted.

l Like "f" but passes control characters and does not make page
breaks.

p Name of a file to print using pr(1) as a filter.

t Troff File. The file contains troff(1) output (cat
phototypesetter commands).

n Ditroff File. The file contains device independent troff
output.

d DVI File. The file contains tex output (DVI format from
Stanford).

g Graph File. The file contains data produced by plot(3).

c Cifplot File. The file contains data produced by cifplot.

v The file contains a raster image.

r The file contains text data with FORTRAN carriage control
characters.

1 Troff Font R. Name of the font file to use instead of the
default.

2 Troff Font I. Name of the font file to use instead of the
default.

3 Troff Font B. Name of the font file to use instead of the
default.

4 Troff Font S. Name of the font file to use instead of the
default.

W Width. Changes the page width (in characters) used by pr(1) and
the text filters.

I Indent. The number of characters to indent the output by (in
ascii).

U Unlink. Name of file to remove upon completion of printing.

N File name. The name of the file which is being printed, or a
blank for the standard input (when lpr(1) is invoked in a
pipeline).

The system does not contain output formatters for the more exotic
output formats. Specifically, the Troff File, Ditroff File, Graph
File, Cifplot File, raster image, Fortran carriage control and the
alternate font specifiers are not handled with Release 1.0 of
MachTen.

If a file can not be opened, a message will be logged via syslog(3)
using the LOG_LPR facility. Lpd will try up to 20 times to reopen
a file it expects to be there, after which it will skip the file to
be printed.

Lpd uses flock(2) to provide exclusive access to the lock file and
to prevent multiple daemons from becoming active simultaneously.
If the daemon should be killed or die unexpectedly, the lock file
need not be removed. The lock file is kept in a readable ASCII
form and contains two lines. The first is the process id of the
daemon and the second is the control file name of the current job
being printed. The second line is updated to reflect the current
status of lpd for the programs lpq(1) and lprm(1).

FILES
/etc/printcap printer description file
/usr/spool/* spool directories
/usr/spool/*/minfree minimum free space to leave
/dev/lp* line printer devices
/dev/printer socket for local requests
/etc/hosts.equiv lists machine names allowed printer access
/etc/hosts.lpd lists machine names allowed printer access,
but not under same administrative control.

SEE ALSO
lpc(8), pac(8), lpr(1), lpq(1), lprm(1), syslog(3), printcap(5)
"4.2BSD Line Printer Spooler Manual" (see MachTen System & Network
Administration manual)