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NAME    [Toc]    [Back]

     lpd - line printer spooler daemon

SYNOPSIS    [Toc]    [Back]

     lpd [-dlsrW] [-b bind-address] [-n  maxchild]  [-w  maxwait]

DESCRIPTION    [Toc]    [Back]

     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
     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 options are as follows:

     -b      Normally, if the -s option  is  not  specified,  lpd
will listen on
             all network interfaces for incoming TCP connections.
The -b option,
 followed by a bind-address specifies that  lpd
should listen
             on  that address instead of INADDR_ANY.  Multiple -b
options are
             permitted, allowing a list of addresses to be specified.  Use of
             this  option  silently overrides the -s option if it
is also present
 on the command line.  bind-address can be a numeric host
             name  in  IPV4  or IPV6 notation, or a symbolic host
name which will
             be looked up in the normal way.

     -d      The -d option turns on the  SO_DEBUG  socket(2)  option.  See
             setsockopt(2) for more details.

     -l       The  -l  flag  causes lpd to log valid requests received from the
             network.  This can be useful for debugging purposes.

     -n       The  -n flag sets maxchild as the maximum number of
child processes
 that lpd will spawn.  The default is 32.

     -r      The -r flag allows the ``of'' filter to be  used  if
specified for
             a  remote printer.  Traditionally, lpd would not use
the output
             filter for remote printers.

     -s      The -s flag selects ``secure'' mode,  in  which  lpd
does not listen
             on  a TCP socket but only takes commands from a UNIX
domain socket.
  This is valuable when the machine on which  lpd
runs is subject
  to  attack  over the network and it is desired
that the machine
 be protected from attempts  to  remotely  fill
spools and similar

     -w       The  -w flag sets maxwait as the wait time (in seconds) for dead
             remote server detection.  If no response is returned
from a connected
  server within this period, the connection is
closed and a
             message logged.  The default is 120 seconds.

     -W      The -W option will instruct lpd not to verify a  remote tcp connection
 comes from a reserved port (<1024).

     If  the [port] parameter is passed, lpd listens on this port
instead of
     the usual ``printer/tcp'' port from /etc/services.

     Access control is provided by two  means.   First,  all  requests must come
     from one of the machines listed in the file /etc/hosts.equiv
     /etc/hosts.lpd.  Second, if the ``rs'' capability is  specified in the
     printcap(5)  entry  for  the printer being accessed, lpr 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 daemon begins processing files after it has successfully
set the lock
     for  exclusive access (described a bit later), and scans the
spool 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

     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

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

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

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

     r       DVI File.  The file contains Tex l output DVI format
from Stanford.

     g       Graph File.  The  file  contains  data  produced  by

     c        Cifplot  File.   The file contains data produced by

     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

     U        Unlink.   Name of file to remove upon completion of

     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

     If a file cannot 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

     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

FILES    [Toc]    [Back]

     /etc/printcap                printer description file
     /var/run/lpd.pid             lock file for lpd
     /var/spool/output/*          spool directories
     /var/spool/output/*/minfree  minimum free space to leave
     /dev/lp*                     line printer devices
     /var/run/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    [Toc]    [Back]

     lpq(1),  lpr(1),  lprm(1), syslog(3), hosts.equiv(5), printcap(5), lpc(8),

     4.3BSD Line Printer Spooler Manual.

HISTORY    [Toc]    [Back]

     An lpd daemon appeared in Version 6 AT&T UNIX.

OpenBSD      3.6                           May      18,      2002
[ Back ]
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