Exclusive lock on /dev/null

[Glen Dudek]

In article <9540 at brazos.Rice.edu> jet at karazm.math.uh.edu (J. Eric Townsend) writes:
>
>How do I circumvent this?  I'm using the KIP/CAP software to drive laser
>printers, which requires tricking lpd into sending all of its data to the
>input filter and never seeing it again.  Part of this includes telling it
>the printing device is /dev/null.  If I want to print on two different
>printers at the samet time, one has to wait because the other has an
>exclusive lock on /dev/null.

I had the same problem when we upgraded to Sun OS 4.0.3 - I worked around
it by creating a device for each printer which has the same major and
minor device number as /dev/null, e.g.

    mknod /dev/laserwriter1 c 3 2

Since the exclusive lock is on the inode, having a separate inode for each
printer solves the problem.

	Glen Dudek
	dudek at ksr.com