unexpunging files

[Reti@STONY-BROOK.SCRC.Symbolics.COM (Kalman Reti)]

    Date: Wed, 16 May 90 15:46 PDT
    From: Reti@STONY-BROOK.SCRC.Symbolics.COM (Kalman Reti)

	Date: Wed, 16 May 90 11:23 PDT
	From: Fisher@ALAN.kahuna.decnet.lockheed.com (Scott Fisher)

	Dear SLUG,

		I was wondering if anybody had written utilities that unexpunge
	files that have been accidently expunged.
    I have such a utility for FEP files; I have the beginnings of such a utility for
    LMFS files too.  Both have been used successfully at customer sites though with
    some handholding, as they have no user-interface to speak of and require some
    knowledge of what's going on to be used correctly.  On my personal (but not
    any official) task list is to clean these up and install them in the system.

    Oops, I guess I wasn't specific enough; the salvager will retrieve expunged
    files from the LMFS if you haven't written over them and you don't have
    disk errors.  My tool is an attempt to do this even when LMFS won't come up
    because the partition or the disk is damaged.
As Barmar points out, this previous paragraph is wrong (not much thought went into
my afterthought).  I had forgotten that as part of expunging a file LMFS zeros out
the first header record (called the R0) record, which makes the data of the file
irretrievable.  I probably forgot about this because I consider it a bug; if it
weren't for this, what I said would have been true.

Sorry for any confusion I may have caused.

	Scott Fisher
	fisher@alan.decnet.lockheed.com