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printcap - printer capability data base


Remote Printing
Transfer Statistics
See Also




The Printcap function is a simplified version of the termcap(5) data base used to describe line printers. The spooling system accesses the printcap file every time it is used, allowing dynamic addition and deletion of printers. Each entry in the data base is used to describe one printer. This data base may not be substituted for, as is possible for termcap(5), because it may allow accounting to be bypassed.

The default printer is normally lp, though the environment variable PRINTER may be used to override this. Each spooling utility supports an option, -P printer, to allow explicit naming of a destination printer.

Refer to the "4.3 BSD Line Printer Spooler Manual" for a complete discussion on how to setup the database for a given printer.


Refer to termcap(5) for a description of the file layout. "Name Type Default Description
"af str" NULL "name of accounting file"
"br numnone if lp is a tty, set the baud rate"
( ioctl 2 call)
"cf str" NULL "cifplot data filter"
"ct num120TCP connection timeout in seconds"
"df str" NULL "tex data filter"
( DVI format)
"ff str" '\f "string to send for a form feed"'
"fo bool false print a form feed when device is opened"
"gf str" NULL "graph data filter"
( plot 3 format
"hl bool false print the burst header page last"
"ic bool false driver supports (non standard) ioctl to indent printout"
"if str" NULL "name of text filter which does accounting"
"lf str" /dev/console "error logging file name"
"lo str" lock "name of lock file"
"lp str" /dev/lp "device name to open for output, or" port @ machine "to open a TCP socket"
"mc num0 maximum number of copies which can be requested on"
lpr(1), zero = unlimited
"ms str" NULL "if lp is a tty, a comma-separated," stty 1 -like list describing the tty modes
"mx num0 maximum file size (in" BUFSIZ blocks), zero = unlimited
"nd str" NULL "next directory for list of queues (unimplemented)"
"nf str" NULL "ditroff data filter (device independent troff)"
"of str" NULL "name of output filtering program"
"pc num200price per foot or page in hundredths of cents"
"pl num66 page length (in lines)"
"pw num132page width (in characters)"
"px num0 page width in pixels (horizontal)"
"py num0 page length in pixels (vertical)"
"rc bool false when sending to a remote host, resend copies (see below)"
"rf str" NULL "filter for printing"
FORTRAN style text files
"rg str" NULL "restricted group. Only members of group allowed access"
"rm str" NULL "machine name for remote printer"
"rp str" lp "remote printer name argument"
"rs bool false restrict remote users to those with local accounts"
"rw bool false open the printer device for reading and writing"
"sb bool false short banner (one line only)"
"sc bool false suppress multiple copies"
"sd str" /var/spool/lpd "spool directory"
"sf bool false suppress form feeds"
"sh bool false suppress printing of burst page header"
"sr str" NULL "file name to hold statistics of each datafile as it is received"
"ss str" NULL "file name to hold statistics of each datafile as it is sent"
"st str" status "status file name"
"tf str" NULL "troff data filter (cat phototypesetter)"
"tr str" NULL "trailer string to print when queue empties"
"vf str" NULL "raster image filter"

Each two-letter capability has a human-readable alternate name. "Short form Long form"

"af acct.file"
"br tty.rate"
"cf filt.cifplot"
"ct remote.timeout"
"df filt.dvi"
"du daemon.user"
"ff job.formfeed"
"fo job.topofform"
"gf filt.plot"
"hl banner.last"
"if filt.input"
"lf spool.log"
"lo spool.lock"
"lp tty.device"
"mc max.copies"
"ms tty.mode"
"mx max.blocks"
"nf filt.ditroff"
"of filt.output"
"pc acct.price"
"pl page.length"
"pw page.width"
"px page.pwidth"
"py page.plength"
"rc remote.resend_copies"
"rf filt.fortran"
"rg daemon.restrictgrp"
"rm remote.host"
"rp remote.queue"
"rs daemon.restricted"
"rw tty.rw"
"sb banner.short"
"sc job.no_copies"
"sd spool.dir"
"sf job.no_formfeed"
"sh banner.disable"
"sr stat.recv"
"ss stat.send"
"st spool.status"
"tf filt.troff"
"tr job.trailer"
"vf filt.raster"

If the local line printer driver supports indentation, the daemon must understand how to invoke it.


The lpd(8) daemon creates a pipeline of filters to process files for various printer types. The filters selected depend on the flags passed to lpr(1). The pipeline set up is:
p pr | if regular text + pr(1)
none if regular text
c cf cifplot
d df DVI (tex)
g gf plot(3)
n nf ditroff
f rf Fortran
t tf troff
v vf raster image

The if filter is invoked with arguments:



-w width

-l length

-i indent

-n login

-h host acct-file

The -c flag is passed only if the -l flag (pass control characters literally) is specified to lpr(1). The Width function and length specify the page width and length (from pw and pl respectively) in characters. The -n and -h parameters specify the login name and host name of the owner of the job respectively. The Acct-file function is passed from the af printcap entry.

If no if is specified, of is used instead, with the distinction that of is opened only once, while if is opened for every individual job. Thus, if is better suited to performing accounting. The of is only given the width and length flags.

All other filters are called as:


-x width

-y length

-n login

-h host acct-file

where width and length are represented in pixels, specified by the px and py entries respectively.

All filters take stdin as the file, stdout as the printer, may log either to stderr or using syslog(3), and must not ignore SIGINT.


When printing to a remote printer using rm, it is possible to use either if or of. If both are specified, of is ignored. Both filters behave the same except that they are passed different arguments as above. Specifically, the output filter is terminated and restarted for each file transmitted. This is necessary in order to pass the resulting size to the remote lpd(8).

If the -p flag was passed to lpr(1), pr(1) is not executed locally, but is requested of the remote lpd(8). Any input filtering via if will therefore happen before pr(1) is executed rather than afterwards.

There are some models of network printers which accept jobs from lpd(8), but they ignore the control file for a job and simply print each data file as it arrives at the printer. One side-effect of this behavior is that the printer will ignore any request for multiple copies as given with the -# flag on the lpr(1) command. The rc entry will cause lpd(8) to resend each data file for each copy that the user originally requested. Note that the rc entry should only be specified on hosts which send jobs directly to the printer.

If lp is specified as port @ machine (and rm is not in use), print data will be sent directly to the given port on the given machine.


When a print job is transfered to a remote machine (which might be another unix box, or may be a network printer), it may be useful to keep statistics on each transfer. The sr and ss options indicate filenames that lpd should use to store such statistics. A statistics line is written for each datafile of a job as the file is successfully transferred. The format of the line is the same for both the sending and receiving side of a transfer.

Statistics on datafiles being received would be used on a print server, if you are interested in network performance between a variety of machines which are sending jobs to that print server. The print server could collect statistics on the speed of each print job as it arrived on the server.

Statistics on datafiles being sent might be used as a minimal accounting record, when you want to know who sent which jobs to a remote printer, when they were sent, and how large (in bytes) the files were. This will not give include any idea of how many pages were printed, because there is no standard way to get that information back from a remote (network) printer in this case.


Error messages generated by the line printer programs themselves (that is, the lpd(8) and related programs) are logged by syslog(3) using the LPR facility. Messages printed on stderr of one of the filters are sent to the corresponding lf file. The filters may, of course, use syslogd(8) themselves.

Error messages sent to the console have a carriage return and a line feed appended to them, rather than just a line feed.


lpq(1), lpr(1), lprm(1), hosts.lpd(5), termcap(5), chkprintcap(8), lpc(8), lpd(8), pac(8)
.Rs "4.3 BSD Line Printer Spooler Manual"


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