"find" and {a,c,m}time

[Jay M. Libove]

I use "find (files) | afio (etc...)" to backup my SCO Xenix 286 v2.2.1
filesystem, which is at around 80 megabytes right now. I would like to
be able to do incremental backups, but I'm having a problem...

My manual entry for find(C) (SCO uses bogus manual sections, that should
be find(1) to the real world I think) says:

find pathname-list expression
...
-atime n	True if the file has been accessed in n days.
-ctime n	True if the file has been changed in n days.
-mtime n	True if the file has been modified in n days.

Okay, so "find -?time 3 -print" should find all files ?'d within the
last three days, right? Nope. To wit:
==================================================
[root]/usr/local/bin:(1 ) % ls -lt | head -10
-rwxr-xr-x   1 bin      bin          111 Oct  8 09:10 lpq
-rwxr-xr-x   1 root     root       34513 Oct  7 09:57 pcomm_input
-rwxr-xr-x   1 root     root      180264 Oct  7 09:57 pcomm
-rwxr-xr-x   1 root     root       88865 Oct  7 02:32 vn
-rwxr-xr-x   1 root     root       12432 Oct  6 12:25 lesskey
-rwxr-xr-x   1 root     root       45329 Oct  6 12:25 less
-rwxr-xr-x   1 bin      bin          249 Oct  5 19:06 uulck
-rwxr-xr-x   1 bin      bin           89 Oct  5 08:18 ckuucp
-rwxr-xr-x   1 bin      bin        25775 Oct  4 19:19 psc

[root]/usr/local/bin:(2 ) % find . -mtime 1 -print
./less
./vn
./lesskey
./pcomm
./pcomm_input
[root]/usr/local/bin:(3 ) % find . -mtime 2 -print
./uulck
==================================================
As you can see, -mtime 1 included only those files modified in the day
preceeding, and -mtime 2 included only those files modified in the day
preceeding the day preceeding, _not_ files modified within the last two
days. This obviously makes it difficult to use

% find . -mtime (epoch_days) | afio ...

to back up the filesystem incrementally.

So, is this the correct behaviour for find(1) (oops, pardon me SCO,
find(C)) ?

While I have your attention :-)

Since, correct behaviour or not, this is what I have... does anyone have
Thanks for any suggestions.a suggestion on how to work around this, in
order to do reasonable incremental backups with commands like:

(find appropriate files by date) | afio ...

[ remark: afio is an enhanced cpio ]

Thanks in advance!

Jay Libove		ARPA:	jl42 at andrew.cmu.edu or libove at cs.cmu.edu
5731 Centre Ave, Apt 3	BITnet:	jl42 at andrew or jl42 at drycas
Pittsburgh, PA 15206	UUCP:	uunet!nfsun!libove!libove or
(412) 362-8983		UUCP:	psuvax1!pitt!darth!libove!libove
-- 
Jay Libove		ARPA:	jl42 at andrew.cmu.edu or libove at cs.cmu.edu
5731 Centre Ave, Apt 3	BITnet:	jl42 at andrew or jl42 at drycas
Pittsburgh, PA 15206	UUCP:	uunet!nfsun!libove!libove or
(412) 362-8983		UUCP:	psuvax1!pitt!darth!libove!libove