David, please CC rsync@lists.samba.org in your replies so that others can help you and your messages are archived for others' future benefit.
On Fri, 2009-01-23 at 09:02 +0100, David de Lama wrote: > >> - Finally I want two know if it is possible to change an amount of > >> blocks manually? > >> e.g. I made a 100 MB file with "dd if=/dev/zero of=/home/test.xyz > >> bs=1M count=100" and know I want to change, lets say, 10 blocks of > >> this file. Is it possible? > > >I guess you're performing some kind of test of the delta-transfer > >algorithm? > > > >The block size for each file defaults to approximately the square root > >of its size. You can find out the exact block size rsync is using for a > >file by passing -vvv (--debug=deltasum2 in rsync 3.1.*) and looking for > >"blength=" in the output, or you can specify a block size to use for all > >files with the --block-size option. Then, just overwrite the desired > >areas of the file. > My next question is, how to overwrite the desired areas in a file? Here's an example. Suppose the block size is 900 bytes (i.e., you either specified --block-size=900 or saw blength=900 in the output). Then you could use the following command to overwrite blocks 40 through 45 of the file (counting from 0) with zeros: dd bs=900 if=/dev/zero of=/home/test.xyz seek=40 count=6 To overwrite with random data, change the if=/dev/zero to if=/dev/urandom . -- Matt -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html