Problems with lofs on Sun-3/4, SunOS 4.0, 4.0.1

[Per Westerlund]

Short recapitulation of the problem: Paraphrased, loop-back filesystems
(lofs(4)) are for directories what symbolic links are for files.  But, I
did not succeed in mounting filesystems of type lofs from the /etc/rc
script, which always worked from a shell.

The solution: The variable PATH is not exported in /etc/rc, add "export
PATH" and mounting lofs-type filesystems works.  (Aside: Why is PATH not
exported?  Will I break something when I export it, due to some very
subtle interaction?)

The explanation of the solution:
Whenever /usr/etc/mount encounters a file system type that it does not
recognize, it tries to execute a program called '"mount_%s", <file system
type>', in this case mount_lo.  (This is not documented, I got a
suggestion this was the case by Greg Earle, <earle at sun.com>. Thanks,
Greg.) There is a program /usr/etc/mount_lo, but /usr/etc/mount did not
find it, since it had the default PATH in the environment.  If /etc/rc
exports its PATH, which contains /usr/etc, /usr/etc/mount will find
mount_lo.

	Per Westerlund
	Holistic Technology AB
	Grona Gatan 59
	Gothenburg
	SWEDEN
	+46 31 420370
	perw at holtec.se