Just use rsync -va (possibly with --chown if you want user/group to be different at the destination and with --delete if you want removed files to be deleted) to continue the copy operation, it automatically takes care of figuring out which files still need to be copied and which are already there.
this post was submitted on 07 Dec 2023
45 points (94.1% liked)
Linux
48153 readers
732 users here now
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Rules
- Posts must be relevant to operating systems running the Linux kernel. GNU/Linux or otherwise.
- No misinformation
- No NSFW content
- No hate speech, bigotry, etc
Related Communities
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
founded 5 years ago
MODERATORS
Just use rsync -va
NO STOP!
The default quick check algorithm of rsync is not safe for this. It only checks filesize and modification time to determine if files are equal. After a b0rked copy, these are not to be trusted.
You should add the -c flag so that files are properly checksummed, unfortunately if you have slow storage on either end, this often negates the speed advantage of rsync.
For example, consider this example:
mkdir source
mkdir destination
echo "hello" > source/file.txt
echo "world" > destination/file.txt
touch -r source/file.txt destination/file.txt
rsync -avh source/ destination/
cat source/file.txt
cat destination/file.txt
Contrary to what you might expect, the rsync command copies nothing and the output at the end will show:
hello
world
If you change the rsync command in the example above to rsync -c -avh source/ destination/, it will work as expected.
True if the initial state is unknown but if you do your initial copy and all the later syncs with rsync it is not really necessary since rsync puts the partial files in a temporary location (there are same parameters to control the details of that too).
My memory of the cp command is that attributes such as file times were transferred at the last step. I think this would make rsync safe in most situations where a system crash wasn't involved.
rsync -avP
rsync even supports Alien vs Predator? What doesn't rsync do???
Bring my dad back
All hail the rsync!
We thank the rsync for it's unwavering reliability.
Amen.
Thank you!
Run an md5sum command on the last file in each location and compare. That will tell you if one of them is different and answer your question.
skimming through coreutils’ copy.c, emit_verbose is called on line 2627 while copy_reg is called on line 3103 (in the implementation of copy_internal). at least on my machine, touch /tmp/foo && cp -v /tmp/{foo,bar/} returns an error after printing the verbose output.
I think the one being currently copied? take a look at https://github.com/coreutils/coreutils/blob/master/src/cp.c :)
Another way to check is to
strace cp testfile testfile2
and the sequence in which the message is printed and operations performed can be studied.
It's perhaps a lot to read, but linux tracing tools are worth learning!