cups is blocking /dev/lp1
ekkard gerlach
jack at aiai.de
Mon May 31 10:32:14 PDT 2004
ekkard gerlach wrote:
> cups is sometimes blocking /dev/lp1. Anybody here has made the same
> experience?
> cat file > /dev/lp0 works. The file "file" seems to be sent to
cat file > /dev/lp1 , of course, not /dev/lp0
> /dev/lp1. But the printer doesn't work! (the file "file" is already in
> the right format for printing). After typing cat file > /dev/lp1 for
> about 10 times the printer suddenly works and prints the document for
> one time. There are no queues defined on /dev/lp1 but on /dev/lp0.
> I got the pointer to delete /usr/lib/cups/backend/parallel. Lets
> wait and see if this helps. The blocking appears only sometimes on a PC
> of some of my customers.
>
> The parports are interrupt driven. I already changed lp0 with lp1.
> No success. lp0 was blocked then.
>
> I don't really delete "parallel" but I changed it to
>
> #! /bin/bash
> # see the "CUPS Software Programmers Manual":
> # "Writing Filters" and "Writing Backends"
>
> # debug info in /var/log/cups/error_log
> set -x
>
> # output "Device Discovery" information on stdout
> if [ "$#" -eq "0" ]
> then
> echo 'direct lp0 "Unknown" "lp0 Printer"'
> exit 0
> fi
>
> # have the input at fd0 (stdin) in any case
> if [ -n "$6" ]
> then
> exec <"$6"
> fi
>
> # infinite retries to access the device
> until cat /dev/null >/dev/lp0
> do
> echo 'INFO: cannot access /dev/lp0 - retry in 30 seconds' 1>&2
> sleep 30
> done
> echo 'INFO: sending the data to /dev/lp0' 1>&2
>
> # forward the data from stdin to the device
> if cat - >/dev/lp0
> then
> echo 'INFO:' 1>&2
> exit 0
> else
> echo 'ERROR: failed to send the data to /dev/lp0' 1>&2
> exit 1
> fi
>
>
> It's not my code, I don't understand much. But replacing
> "parallel" with that code printing to lp0 works and lp1
> not (driven by cups). lp1 is untouched. I hope lp1 is
> working without beeing blocked or deferred. Tomorrow there
> will be a test in one of my customers office. Lets wait and see.
>
> using cups 1.1.18 / cupsd , Suse 8.2
>
> tia
> Ekkard
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