So if I had a cp -v operation fail, is the last file name it printed out the last successful file copy, or is it the failed partially copied file? If you had to ensure all files are copied correctly without overwriting anything, would deleting the last filename that was printed from the destination folder delete the partially copied file that the operation failed on?

    • flux@beehaw.org
      1·
      11 months ago

      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!

  • taladar@sh.itjust.works
    0·
    11 months ago

    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.

    • DefederateLemmyMl@feddit.nlEnglish
      1·
      11 months ago

      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.