NAME

       lpd — line printer spooler daemon

SYNOPSIS

       lpd [-dlrs] [-b bind-address] [-n maxchild] [-w maxwait] [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 options are as follows:

       -b bind-address
               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 maxchild
               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 attacks.

       -w maxwait
               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 300 seconds.

       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 or  /etc/hosts.lpd  (which  follows  the  same  syntax  as  hosts.equiv(5)).
       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.

       lpd performs reverse DNS lookups on network clients.  If a client hostname cannot be determined from  its
       IP  address,  the print request will be silently dropped.  This is important to note when debugging print
       problems in dynamic address environments.

       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 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.

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

       g       Graph File.  The file contains data produced by plot.

       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).

       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
       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
       /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

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

       4.3BSD Line Printer Spooler Manual.

HISTORY

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

       lpd previously required that clients connected using a privileged port (below  1024).   This  restriction
       was  removed because it does not provide additional security and also because many modern clients connect
       using an unprivileged port.

Debian                                           April 15, 2008                                           LPD(8)