I'm using guestmount to construct 500mb ext4 filesystem for an embedded built application. Subsequent to an unmount, I want to snapshot the sha256sum of the filesystem. But if I take a copy of the file system first and I calculate the sha256sum several times? I get different answers...Why?

. #untar stuff into file system . sync

guestunmount system.img

#take a copy before calculating the checksum
cp system.img bla
SHASUM=`/usr/bin/sha256sum -b bla | awk '{print $1}'`
echo "SHA SUM is ${SHASUM}"

I added the sync command for good measure, even before I ran it the first time. It STILL gives me the wrong answer. Am I using the guestunmount command incorrectly? Does FUSE have a user space sync command I should run?

I'm running guestmount 1.32.2, linux kernel 4.10.0-42-generic


Well? There is now a "-d (directory)" option added to mke2fs. I was planning on doing this work myself. Somebody beat me to the punch.

My recommendation if you're looking for a simple solution is to use mke2fs and stay away from guest mount.

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