I use a script to partition and format CF cards (connected with a USB card writer) in an automated way. After the main process I check the card again with fsck. To check bad blocks I also tried the '-c' switch, but I always get a return value != 0 and the message "FILE SYSTEM WAS MODIFIED" (see below). I get the same result when checking the very same drive several times...

Does anyone know why a) the file system is modified at all and b) why this seems to happen every time I check and not only in case of an error (like bad blocks)?

Here's the output:

linux-box# fsck.ext3 -c /dev/sdx1
e2fsck 1.40.2 (12-Jul-2007)
Checking for bad blocks (read-only test): done
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information

Volume (/dev/sdx1): ***** FILE SYSTEM WAS MODIFIED *****
Volume (/dev/sdx1): 5132/245760 files (1.2% non-contiguous), 178910/1959896 blocks