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Conference 7.286::postscript_printing

Title:	Digital PostScript printers and their associated software

Moderator:	REGENT::LASKOHER

Created:	Wed Jan 24 1990
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	7230
Total number of notes:	31971

7139.0. "/print {pop} def ? Digital UNIX What does it mean?" by EVTAI1::BROCHARD (Manuel Brochard - French CSC) Wed Apr 02 1997 04:09

    Hi,
    
    	I'm using Digital Unix v4.0 and ln03rof print filter.
    
    	When I try to print a postscript file, generated by an application, 
	(the file begins with %!PS-Adobe),
    	the ln03rof filter (and all the ln0*rof print filters) prepends
    	the following line to the original postscript file :
    	"/print {pop} def"
    
    	What does it means ?
    	Is there a way to remove this line, because non-DEC printers
    	don't like it. (it prints successuflly on DEC printers).
	    	
        Thanks for info,
    
    Manuel.
    
     1)	orginal file : test.ps
    	%!PS-Adobe
    	statusdict begin { true setduplexmode } .....
    
     2) invocation of ln03rof filter :
    	
    	# /usr/lbin/ln03rof < test.ps | more 
>	/print {pop} def      <---- new line added..
>    	%!PS-Adobe-1.0
    statusdict begin { true setduplexmode }

T.R	Title	User	Date	Lines
7139.1		SMURF::LABONTE	`Wed Apr 02 1997 10:20`	10
	/print {pop} def disables the postscript print command. The idea is to prevent the postscript printer from sending info back to the host system. While this isn't bullet proof it does seem to resolve most of the chatty postscript programs. If the printer isn't prevented from sending info back to the host there is a possibility that the communication between the host and printer will lock up. Under certain conditions the filter would not start the output data with a %!. This would cause problems with auto sensing printers. This has been fixed but hasn't been released on an SSB kit.
7139.2		REGENT::POWERS	`Wed Apr 02 1997 11:53`	10
	To clarify a bit, the PostScript 'print' command takes a string argument and returns it on the backchannel to the host. print commands are often used diagnostically in PostScript code to return information from the printer to the host. The command fragment given refines 'print' to discard rather than return this argument. No print job should fail because of this redefinition, but there could be certain scope situations in which a conflict could result. - tom]