Tell me more ×
Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems.. It's 100% free, no registration required.
up vote 3 down vote favorite

I have a ext3 filesystem on a .img file. After mounting and unmounting it, I noticed that the md5sum is changed, even if no file inside was changed!

md5sum myfilesystem.img
XXXX myfilesystem.img
mount -t ext3 myfilesystem.img temp/
umount temp/
md5sum myfilesystem.img
YYYY myfilesystem.img

Why does XXXX differs from YYYY? I clearly didn't touch anything inside myfilesystem.img.

share|improve this question
2  
last mount date is stored :) – gasko peter Feb 15 at 14:16

1 Answer

up vote 6 down vote accepted

Because, if you mount the ext3 in writable mode, there are a few things that get updated, like the last mount date. Try if this also happens when you mount with -o ro.

share|improve this answer
With -o ro the md5sum is not changed. – michelemarcon Feb 15 at 14:58
1  
Note that sometimes, even mounting with -o ro doesn't guarantee that nothing gets written. See the man page for mount under --read-only. – Michael Kjörling Feb 15 at 15:35

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.