Xref: utzoo comp.sys.att:7479 unix-pc.general:3675
Path: utzoo!attcan!uunet!ginosko!usc!ucsd!rutgers!gatech!mcdchg!chinet!les
From: les@chinet.chi.il.us (Leslie Mikesell)
Newsgroups: comp.sys.att,unix-pc.general
Subject: Re: Incremental backups on 3b1?
Summary: hard to get right
Message-ID: <9474@chinet.chi.il.us>
Date: 3 Sep 89 04:31:38 GMT
References: <16730@pasteur.Berkeley.EDU> <9316@cbnews.ATT.COM>
Reply-To: les@chinet.chi.il.us (Leslie Mikesell)
Followup-To: comp.sys.att
Organization: Chinet - Public Access Unix
Lines: 27

In article <9316@cbnews.ATT.COM> mvadh@cbnews.ATT.COM (andrew.d.hay,54242,wi,1d007,508 374 5484) writes:
>"	I am looking for a way to do incremental backups on my 3b1.

>read up on find(1) and cpio(1).
>you will want something like:
>find / -newer [date-spec] -print | cpio -Boacv > /dev/rfp020
>					^^^^^^	 ^^^^^^^^^^^
>				    all options on	|
>						the raw floppy

Not quite - the "newer" option should be followed by a filename
and all files whose modification times are newer than the specified
file are selected.  Normally you would "touch" a file at the beginning
of a backup, then "mv" it to the correct after the backup is complete.
However, you should be aware that this method will not find files
that have been moved or renamed instead of modified, or files that
have had their modification times intentionally set earlier (as would
happen if you use cpio -ivmd to load files that were stored earlier
or created on another machine keeping their actual timestamps).  Using
find / -ctime -days  will get all the files whose inodes have been
modified in the last "days" which will catch all modifications, but
you need to keep track of the days since the last backup.  Also, using
the -a flag to cpio (reset the access time so it appears the file
hasn't been read) will cause an inode modification and make a ctime-based
find select the same files again the next time.

Les Mikesell