verify successful cp like xcopy does in windows?

carl0ski · 10-25-2006, 03:45 AM

What routine will best verify that a very large quatity of files copy correctly to a new disk?

preferably bash command

matthewg42 · 10-25-2006, 06:03 AM

The regular cp command will print an error message on the standard error file handle and set the $? environment variable to non-0 if an error was encountered while copying.

If you want to keep a log of errors during a large copy, you can re-direct the standard error messages to a file. For example, with this large recursive copy command, we send any error messages to cp_errors, and send a mail containing those errors if there were problems:

Code:

cp -R /var /mnt/backup 2> cp_errors
if [ $? -ne 0 ]; then
  cat cp_errors | mailx -s "copy errors" my@email.address
fi

You can also do a similar thing like this, which is a little easier to do from the command line:

Code:

cp -R /var /mnt/backup 2> cp_errors || \
    echo "You got errors - see cp_errors"

j88pers · 11-03-2006, 03:14 PM

I use md5sum. It generates a checksum against the file & can compare that against the written file.

something like this:

Code:

find /path_to_files | while read in; do
  md5sum "$in" >> /tmp/copy.md5
done

>>do the copy<<

this writes the md5 checksums to a text file for later verification. You could also use just sum as it's quicker. (but it may not offer the compare to file - man sum)

Then to verify I just use md5sum again on the target directory:

Code:

cd /target directory
md5sum -c /tmp/copy.md5

as others said, you can redirect std out and std error to files for your own comfort.

Code:

md5sum -c /tmp/copy.md5 &> /tmp/crc.out