printcap -- printer capability data base
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 dele- tion 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 discus- sion 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 num none if lp is a tty, set the baud rate (ioctl(2) call) cf str NULL cifplot data filter ct num 120 TCP 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 num 0 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 num 0 maximum file size (in BUFSIZ hundredths of cents pl num 66 page length (in lines) pw num 132 page width (in characters) px num 0 page width in pixels (horizontal) py num 0 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 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 var- ious 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: if [-c] -wwidth -llength -iindent -n login -h host acct-file The -c flag is passed only if the -l flag (pass control characters liter- ally) 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: filter -xwidth -ylength -n login -h host acct-file 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. Specifi- cally, the output filter is terminated and restarted for each file trans- mitted. 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 writ- ten 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.
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