> Quick question....can anyone explain to me when the data in a file > might change without changing the mtime, ctime or size? I'm not > sure I've ever come across that before. An example might help me > determine if I can safely remove -c.
It's possible on Unix systems, but not practical. An example script: #!/bin/sh # Run on a BSD Unix system, your touch(1) arguments may vary echo "foo" > File touch -t 200205300800 File ls -l File echo "foo" > File ls -l File touch -t 200205300800 File ls -l File Output: -rw-r--r-- 1 ziegast ziegast 4 May 30 08:00 File -rw-r--r-- 1 ziegast ziegast 4 May 30 11:19 File -rw-r--r-- 1 ziegast ziegast 4 May 30 08:00 File Here's one example where I might use -c: Hackers are not known for being practical. They like to cover their tracks as best they can by setting the owner, group, permissions, size, mtime, and ctime of their fake programs to be the same as the original programs. If you're distributing system software using rsync or rdist, you may want to force checksum comparisons just to be sure. One might also use rsync with "-n -c" to help compare a "gold copy" of OS files with an active system. Then again, tripwire was designed to do this better. Another example is when some network-based filesystems delay updating their metadata even though the content has changed. I remember once using a client machine to update a file on a busy NFS server. It took several seconds for the change to be seen by another client machine. If I were using rsync on the second client machine, its view of the file might be inconsistent. Then again, best practices would dictate my wanting to run rsync on the NFS server and not on the clients that might be inconsistent with the server (to keep network traffic down and reduce overhead). -- Eric Ziegast -- To unsubscribe or change options: http://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.tuxedo.org/~esr/faqs/smart-questions.html
