Wriiting to /dev/lp0 in SCO UNIX 3.2.4

Wriiting to /dev/lp0 in SCO UNIX 3.2.4

Post by Robert Tillya » Sun, 24 Jul 1994 12:48:04

                    Writing to the parallel port in
                           SCO UNIX 3.2.4

We have written a printer spooler that is able to detect printer problems
by setting an alarm() prior to a putc() call, our problem is that when we
are talking to /dev/lp0 and there is some reason why the read times out a
signal would be expected as occurrs with the serial ports but the process
just locks up until the putc() is able to write to lp0 (ie. they plug the
printer back in again), in this case the signal goes off after the putc()

Why is it that the signal/alarm soloution works on serial ports but not a
parallel port?  Is there any way that I should be checking that the write
will not block prior to writing? I need to know which characters don't go
to the printer so that when the operator resumes the print it'll continue
from where it left off.

Thanks in advance

Robert Tillyard               AT Veterinary Systems Ltd.,

+44 359-258411                Bury St Edmunds, Suffolk, IP31 3HA. UK.


1. ls > /dev/lp0 fails--but /dev/lp0 exists

I'm new to Linux.  I just loaded the Slackware distribution onto Swan 386SX,
386DX/25 and 486DX.  I have the same problem on all of them:

ls > /dev/lp0 gives:    
    bash: /dev/lp0: no such device.

ls -al /dev/lp0 gives:  
   crw-rw----  1  root  lp   6,  0  Nov 30 14:30  /dev/lp0

Nothing prints.  

All these machines print fine on lpt1: under DOS.  I've read the
print HOWTO and "Linux Installation and Getting Started."   On the 386SX,
uname -a gives:  
    Linux alinux 1.0 #9 Tue Mar 15 18:27:34 CST 1994  i386

I'd appreciate any help you can give.

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