Copy and verify a directory in Linux

jismagic · 04-27-2013, 07:44 AM

Hello

I m transferring a folder from usb to local drive. I am using cp -r command to do it,
which works for me. But I want to verify if the file is transferred good.

I thought of 2 things - file size verification and CRC verification.

1, File size is different in usb drive and local drive - a few bytes different,
2. CRC verification is good.. but not sure how to do it..
I tried using cksum. is it OK to CRC a directory with cksum? If not, how i can
CRC all files in the directory?

3. Any other ideas?

thanks,
jis

Sigg3.net · 04-27-2013, 07:54 AM

Use 'sync' command to flush "temporary" data to disk. I always use this when transferring to USB devs.

Then, if you are paranoid, run md5sum on fileonpc vs fileonusb and see if the checksums are identical:

Code:

$ md5sum /home/file
123456767888999
$ md5sum /media/usb/file
123456767888999

This is just a mockup, but if the two numbers are identical the files are identical.

But if I understand you correctly, it's just about knowing that the data has actually been written. In that case, the sync command is your friend.

TobiSGD · 04-27-2013, 07:55 AM

Try to copy the files again, this time with rsync and the -c option. rsync will compare source and destination files based on a checksum before it copies and skip files that are the same in source and destination. So if rsync does not copy a file you can be sure that the copy is not corrupted.
Example:

Code:

cp -r /source /destination
rsync -avc /source /destination

eSelix · 04-27-2013, 07:57 AM

You can use md5sum for generating and checking:

Code:

md5sum /some_directory/* > checksum.md5
md5sum -c checksum.md5

hans66 · 07-29-2014, 10:24 AM

https://sourceforge.net/projects/crcsum/ has cp & mv with crc checksum