Am 2026-03-02 11:53, schrieb Dale:
Howdy,
I did my weekly backups overnight. I had a lot of new files. I was
wondering tho, can I generate a checksum or something for the
directory on my main rig and then generate it for my backup copy and
then compare the two checksum results?
You can use `find` to generate a checksum for every file:
find /path/to/dir -type f -exec md5sum {} \; > output.md5
Then, you transfer the output file to the new machine and run md5sum -c:
md5sum --check < output.md5
Beware that the path needs to match. So you may need to adjust the
first parameter of `find` or play around with `sed` a bit.
For example, I use this to verify the backup of my ~ folder. First,
I go to /home/philipp and run
find home/philipp/ -type f -exec md5sum {} \; > /tmp/home.md5
Then, I go to the folder where I did the test restore, and verify:
$ cd /mnt/data/backup-test-restore
$ ls
home
$ cd home
$ md5sum -c /tmp/home.md5
While at it, how long would it take to do a directory that is about
42TBs in size? If it would take a long time to do it that way, is
there a faster way to make sure the files match in a fairly quick way?
It depends on the checksum algorithm. In the example above I used md5,
which is considered deprecated, but fairly fast. Other examples would be
sha256sum, sha512sum, etc.
Also, I use rsync to copy the files to the NAS box. Maybe it can do
some sort of check while copying the files over???
rsync has a --checksum flag for this.
Also, you may want to look at rclone, which is a bit more sophisticated
for
use cases like this:
https://rclone.org/commands/rclone_sync/
HTH
