4.20. Interfacing to Non-LPRng Spoolers

Given the large number of defective RFC1179 implementations that are currently in use, there will come a time when the administrator will discover that their printer with its built-in network interface, the non-UNIX based print spooler on a mainframe, or even a new print spooler on a new OS distribution will not accept jobs from the LPRng system. Usually this is caused by the presence, absence, or order of lines in the control file being sent to the remote system. To deal with this particular problem, the :bk, :control_file_line_order, :nline_after_file, and :control_filter options are used.

The :bk (BSD Kompatibility) option causes the lpd server to remove all but an extremely small subset of lines from the control file, and to put the lines in the most commonly used order. In addition it will make the control and data files names extremely short and simple. This almost always solves compatibility problems when sending jobs to older vintage print spoolers or UNIX systems.

If this does not solve the problem, then you can specify the allowed control file lines and their order using the control_file_line_order=... option. For example, control_file_line_order=CJPMD would allow only control file lines starting with C, J, P, M, and D, and this order in the control file. Note that this does not provide missing line values, it only controls line values that are present in the control file. You should also use the :bk option as well.

You might run into some really unusual implementations where the control file N (file name) information must come after the control file name. This is forced by the :nline_after_file option.

If these horrible kludges do not solve your compatibility problems then we turn to the very large hammer and edit the control file. The very last step before transfering the control file to the remote server is to filter it using the :control_filter=/path program specified in the printcap. The :control_filter reads the control file from STDIN and writes the modified control file to STDOUT. No consistency checking or validity checks are done on the new control file and the result is transferred directly to the remote system. If the :control_filter exits with a 0 status, then the normal processing continues. Any other status will cause the transfer operation to be aborted and an error reported.