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From: davy@pur-ee.UUCP (Dave Curry)
Newsgroups: comp.unix.questions
Subject: Re: file times
Message-ID: <6237@pur-ee.UUCP>
Date: Fri, 22-May-87 22:35:27 EDT
Article-I.D.: pur-ee.6237
Posted: Fri May 22 22:35:27 1987
Date-Received: Sat, 23-May-87 19:46:40 EDT
References: <12854@watnot.UUCP> <994@oliveb.UUCP>
Reply-To: davy@pur-ee.UUCP (Dave Curry)
Distribution: na
Organization: Purdue University Engineering Computer Network
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>In article <12854@watnot.UUCP> djfiander@watnot.UUCP (David Fiander) writes:
>I just finished reading the MINIX book.  It is basically V7 compatible, except
>it only stores modification time in the i-nodes (like MS-DOS).  This was done
>for space reasons.  My question is: do any of the usual UNIX utilties/programs
>use the creation/access times in a file, or were they just put in because some-
>body thought they might be useful?
>

Yes.  "dump" uses the inode change time (it is *not* the creation time)
to decide what to dump to tape.  Not having it and not storing
modification times on the disk would make partial dumps basically
impossible, at least under the current scheme.

Access time, as previously mentioned, is used for the "mail"/"new mail"
hack.  It is also used to determined idle time by finger, w, etc.  One
other thing it's useful for is to see if a program has been executed --
"ls -lu file" is a great way for debugging things like inetd when they
act up.  (For those of you who don't follow, executing a program updates
its access time.  For those of you completely in the dark, the secret's
to bang the rocks together, guys.)

Storing the modification time only in memory is cute I suppose, but
probably makes the "make" utility rather useless after rebooting the
system... Somehow recompiling the entire kernel every time when
debugging something new just doesn't turn me on...  'Course, I suppose
MINIX compiles a little quicker than 4.3BSD, so maybe it isn't a big deal.

--Dave Curry