lpd(8)							      System Manager's Manual							    lpd(8)

NAME

       lpd - line printer daemon

SYNOPSIS

       /usr/lbin/lpd [-l]

FLAGS

       Causes the lpd daemon to log valid requests received from the network.  This  flag is useful for debugging.

DESCRIPTION

       The  lpd line printer daemon (spool area handler) normally is invoked at boot time.  The daemon makes a single pass through the printcap(4)
       file to determine the existing printers and to print all files that were not printed before the system shut down.  The daemon  uses  system
       calls  listen(2)  and accept(2) to receive requests to print files in the queue, to transfer files to the spooling area, and to display the
       queue or remove jobs from the queue.  In each case, the daemon forks a child process to handle the request so that the parent  process  can
       continue  to  listen  for  more requests.  The Internet port number used to interact with other processes is identified with the getservby-
       name(3) system call and is specified in the /etc/services file by its printer service record entry.

       Access control is provided by the following means:

       All requests must originate from one of the machines listed in the /etc/hosts.equiv or /etc/hosts.lpd file.

       When an rs capability, which restricts remote users to those with local accounts, is specified in the /etc/printcap file  for  the  printer
       being accessed, an lpr or lp request is honored only for those users having accounts on the same machine as the printer.

       The  minfree  ASCII  file  in each spool directory contains the number of disk blocks to leave free so that the line printer queue will not
       completely fill the disk.

       The lock file in each /usr/spool subdirectory is used to prevent more than one active lpd daemon and to store information about the  daemon
       process for other printer spooling commands.

       After  the  lpd	daemon	has  successfully set the lock in the lock file, it scans the /usr/spool subdirectory for files beginning with the
       characters cf.  Records in each of the cf files specify files to be printed or specify one or more non-printing actions	to  be	performed.
       Each such record begins with a key character that specifies what to do with the remainder of the line.  In the following table, the columns
       list the beginning key character, the key-character name, and its purpose: Name of the machine where the lpr daemon or the lp  command  was
       invoked.   Login name of the person who invoked the lpr or lp commands.	This record is used to verify ownership by the lprm or cancel com-
       mands.  String to be used for the job name on the burst page.  String to be used for the classification line on the burst page.	The record
       line  provides  identification  information from the etc/passwd file and initiates banner page printing.  The number of character spaces to
       indent the output (spacing is from the ASCII character set).  Sends mail to the specified user when the current print job completes.   Name
       of  another  font file to use in place of the default font file.  Name of another font file to use in place of the default font file.  Name
       of another font file to use in place of the default font file.  Name of another font file to  use  in  place  of  the  default  font  file.
       Changes	the  page  width  (in  characters) used by the pr command and by text filters.	Selects the input tray that supplies paper for the
       print job.  Selects the output tray where the printed paper is deposited.  Specifies the orientation of the printed  output  on	the  page.
       Note  that for certain print filters, such as pcfof, the O flag is used to specify other options such as even to print even-numbered pages.
       Specifies whether the job should be printed on both sides of the physical sheet and whether the pages should be	rotated  by  180  degrees.
       String  to be used as the title for the pr command.  Name of an already formatted file to print.  Name of a file to print using the pr com-
       mand as a filter.  Similar to f, but passes control characters and does not make page breaks.  The file contains troff output  (cat  photo-
       typesetter  commands).	The  file  contains DVI (device-independent) troff output.  The file contains Tex(l) output (DVI format from Stan-
       ford).  The file contains a raster image.  The file contains data produced by the cifplot command.  The file contains text data	with  For-
       tran  carriage control characters.  Do not interpret any control characters in the file.  Name of file to remove on completion of printing.
       The name of the file undergoing printing, or when blank, for the standard input (when the lpr or lp command is invoked  in  a  pipeline	or
       when the command is invoked from the standard input).

       Whenever  a file cannot be opened for printing, a message is logged via the syslog(3) subroutine using the LOG_LPR facility.  In this case,
       the lpd daemon tries to reopen a file, which it expects to be referenced by a correct pathname, up to 20 times.	If a file cannot be opened
       after 20 tries, lpd goes to the next file.

       The   lpd  daemon  uses	the  flock(2)  system call to provide exclusive access to the lock file and to prevent multiple daemons from being
       simultaneously activated.  If the daemon is killed or dies unexpectedly, the lock file does not have to be removed.

       The 2-line ASCII /usr/spool/lock file contains two lines.  The first line specifies the process ID of the daemon, and the second line spec-
       ifies  the control file name of the job currently undergoing printing.  The second line is updated to reflect the current status of the lpd
       daemon for commands lpq, lprm, cancel, and lpstat.

   NOTE - Printer Log Files
       The lpd does not automatically purge log files.	You should monitor logs regularly or set up a cleaning task using the cron  command.   See
       similar commands for syslog.dated in /usr/var/spool/cron/crontabs

FILES

       Specifies the command path.  Printer description file.  Spool directories.  The location of spool directories is a convention, but not nec-
       essary (see the /etc/printcap file).  The transient lock file which records print daemon and job status.  On clustered systems, this  tran-
       sient file is created to contain the daemon status.  Note that the /usr/spool/lpd directory is a Context Dependent Symbolic Link (CDSL) and
       should not be manually created or destroyed.  Minimum free disk space to leave.	Line printer devices.  Socket for local  requests.   Lists
       machine	names  allowed	access to a printer.  Lists machine names allowed access to a printer, but which are not under same administrative
       control.

RELATED INFORMATION

       Commands:  cancel(1), lp(1), lpc(8), lpr(1), lpq(1), lpstat(1), lprm(1), pac(8), pcfof(8)

       Calls:  syslog(3) delim off

																	    lpd(8)