Re: [TCLUG:407] Replacing netware with l

[mikk0022@maroon.tc.umn.edu]

On Fri, 12 Jun 1998 13:10:00 -0500 Brad DeJong wrote
>Not really.  However, you can alias the rm command to do pretty much   
>whatever you want.  I.E. even though there is no such feature built-in a   
>simple "alias 'rm $1' 'mv $1 /tmp/deleted" (I know this probably isn't   
>correct syntax) can do much the same thing in combination with a cron job   
>that checks space and does a first-in first-delete kind of thing.

Actually, whenever I want to cover my butt when editing files, I
just check them in to RCS.  That squirrels them away in to a
directory in which I can't delete them without changing permissions,
and also keeps the old versions handy (using reverse diffs).  Quite
a piece of work, that RCS.  It's practically ideal for one person's
work.

There is an emacs package (for those of you who are so inclined)
called vc.el, which is supposed to provide convenient access to
RCS from within emacs.  I don't use emacs for editing, so I can't
comment on that package.

>>Does linux have anything like the "salvage" function of Netware?  One of   
>the
>>things about Netware that saves us from time to time is that it keeps   
>past
>>versions of files after they have been updated....so that if we delete a
>>file by mistake or save a bad version, I am able to dig out other recent
>>versions from which to choose.

Ahhhh... versioning filesystems.  They fit in perfectly with VMS,
where the namespace was clunky enough (DEVICE:[dir.subdir]file.ext;ver)
that the version number just fit in.  Of course, this bit quite a
few people every now and then.  You'd think that the command ERASE
*.* would actually clear out a directory, right?  Wrong.  It only
removed the "head" versions of all the files (i.e. *.*;1).  So
you'd have to type ERASE *.*;* in order to actually clear out the
entire directory.  One of my favorite annoyances was that, without
dutifully cleaning up after yourself, frequently edited files would
take up lots of directory entries -- one for each time you saved
the file.  VMS might have been a great, stable system, but its
interface was downright hideous.

There once was a VMS-style versioning filesystem available for
Unix, called cedar, IIRC.  It presented a standard Unix filesystem
interface, except filenames had "!<version>" appended to them.
This filesystem is, along with VMS, 4.2BSD's IBIS remote filesystem,
MVS, DOS, and e-mail addresses (quite a combination, eh?) are all
discussed/critiqued in a quite thoughtful paper by Rob Pike and
P.J. Weinberger, called "The Hideous Name."  It's available on-line
at <http://plan9.bell-labs.com/cm/cs/doc/85/1-05.ps.gz> -- it is most
definitely on my "recommended reading list."

Although it's not strictly "versioning", the original plan9
installation had a beautifully-done service, known as "time travel
backup."  Every morning, modified portions of the filesystem would
be flushed to a WORM jukebox.  These backups were presented as
snapshots of the filesystem under directories given by the date of
the snapshot.  For example, to get at /lib/libc.a from April 13,
1998, you would access it with /1998/04/13/lib/libc.a   This was
quite elegant, in that all snapshots, as well as the current
filesystem, were available from within the same namespace.

-Chris