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From: rchui@neptune.nswc.navy.mil (Chui)
Newsgroups: aus.computers,comp.dcom.lans,comp.periphs.printers
Subject: Re: Laser Printing in a Student Lab Environment
Message-ID: <1991Jun20.130225.7752@relay.nswc.navy.mil>
Date: 20 Jun 91 13:02:25 GMT
References: <1991Jun20.110938.30701@qut.edu.au>
Sender: news@relay.nswc.navy.mil (0000-Admin(0000))
Reply-To: rchui@neptune.nswc.navy.mil (Chui)
Organization: Naval Surface Warfare Center, Dahlgren VA
Lines: 92

3.  How does the IIIsi behave in a mixed environment (Macs and PC's)?  Can
    it switch between postscript and HPGL automatically?

---------------------------------------------------------------------------

	I am really interesting this question. I have installed a PostScript
cartridge in HP LaserJet III. I am try to write a output filter file in
C for my
Sun3 os 4.0 system. This output file performed:

1) chech if there any print job on tty## printer port?
2) check if that print file is a postscript file? (this is option)
3) if no print job and is a postscript file, then sent signal to printer to
   switch to PostScript mode, print postscript file. 
4) Reset to PCL mode.



	Here is my C code. After I compiled the file, and modify the /etc/printcap
file. 
I try to print by "lpr -h -Pprintername filename". where -h is suppress the
burst page which is not in postscript code.

This program is work to detect the print jobs and set signal to switch to
postscript mode, after that the printer just do nothing, the postscript file 
never print. But when run this program by input a file("ofps <
filename), it works fine, it works everything what I want! 

 Is there anyone out there know why is that? 

#include <stdio.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/dir.h>

char *SD="/usr/spool/lpd/hplp";

main(argc,argv)
int argc;
char *argv[];
{
        register char *cp;
        register int ch;

        /* 'of' filters are only passed width and length arguments from lpd */
        while (--argc)
        {
                if (*(cp = *++argv) == '-' )
                {
                        switch (cp[1])
                        {
                        case 'w':
                                /* this filter does nothing with width */
                                break;

                        case 'l':
                                /* this filter does nothing with length */
                                break;

                        }
                }
        }

        while (checkq()) /* If there any print job on tty## port? */
                system("sleep 20");
        printf("\033&l1057.32259J"); /*  reset and switch to PCL */
        (void) fflush(stdout);
        system("sleep 50");         /* printer takes 45 sec to reset */
        printf("\033&l5257.1058J"); /* to PS mode */
        (void) fflush(stdout);
        system("sleep 50");
        while ((ch=getchar()) != EOF) {
                putchar(ch);
        }
        exit(0);
}
int checkq()
{
        register struct direct *d;
        DIR *dirp;
        int nitems=0;

        if ((dirp = opendir(SD)) == NULL) /* open the lpq directory */
                return(-1);
        while ((d = readdir(dirp)) != NULL) /* list the files */
                if (d->d_name[0] == 'c' && d->d_name[1] == 'f')
                        nitems++; /* If there are files begin with "cf"
print jobs
					*/
        closedir(dirp);
        return(nitems);
}