ian@sibyl.eleceng.ua.oz.au (01/15/90)
I was bitten by the tar -N flag the other day. I was upgrading my OS and I thought I could save all my changed files (/etc/passwd, /etc/inittab etc etc) by: cd /; tar -clf /usr/new.files -N <installation date> . This failed because the system had been saved and restored several times and tar effectively uses the most recent of the file modification time (mtime) and the inode change time (ctime). Restoring from a tar, cpio or dump file updates ctime. I understand why tar uses this criteria, it means that files whose access permissions or ownership have changed get archived. It is unfortunate that tar cannot restore ctime when extracting files (but that is an OS limitation). However, I think I had a natural and resonably frequent use for the -N flag so how about, a) documenting the behaviour a little more clearly and b) yet another flag which means files whose mtime is > date.