Re: [PLUG] Creation times on unix files

[gabriel rosenkoetter <gr@eclipsed.net>]

On Thu, Feb 01, 2007 at 01:40:39PM -0500, Mark Dominus wrote:
> I wrote to Dennis Ritchie, one of the authors of Unix, to ask where it
> had gone; he said he thinks they took it out because they did not find
> it useful.

I think you would do better to ask Kirk McKusick, since the current
{a,c,m}time semantics are *file system* semantics, and basically all
modern file systems on Unix-like operating system start from his
(well, mostly, obviously not alone) Berkely Fast File System
implementation (on BSD, rather than Sys V, but it's where modern Sys
V derivatives get their various UFS semantics mostly, never mind
basic directory and metadata logical structures).

I'm not so sure you'll get a less handwavy answer than you did from
Dennis, though. Nobody's too sure on this one. (Windows, btw, DOES
have this and a host of other file system metadata than Unix hasn't
got--until it got hacked on later in many cases, excluding creation
time, by way of various ACL implementations--because it lifted that
along with a security model from VMS.)

I only just skimmed your referenced post, but I'm not sure you
clearly state the real difference between mtime and ctime in the
modern POSIX world there, which is "mtime is modification of file
contents, ctime is modification of file inode metadata". (Explicit
positional use of "file" and "inode" purposeful; they're not
interchangeable. Especially, cf clustered file system
implementations... I think like Veritas's cfs in the latest VxVM,
though I didn't check just not to make sure that it does what I
think it does, where files are a global concept but inodes are a
local-copy one. Maybe also see AFS, thought that starts to break
down a bit anyway because it's a network file system, and doesn't
cheat this stuff all that much more than NFS already does.)

-- 
gabriel rosenkoetter
gr@eclipsed.net

Attachment: pgp7hFGkYwbwK.pgp
Description: PGP signature

___________________________________________________________________________
Philadelphia Linux Users Group         --        http://www.phillylinux.org
Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion  --   http://lists.phillylinux.org/mailman/listinfo/plug