Hi Ralf,
> I want to check the integrity of USB transferred, saved files by using
> a tool, without manually clearing cached data manually.
Why do you want to avoid manually clearing the cache?
The problem with clearing the cache is it is the cache for every device.
It is better to simply umount(8) and then mount(8) the USB stick so its
blocks in the cache are discarded and reads must access the device.
With the cache empty, a simple ‘diff -qr src dest’ will show if any
files' contents differ, reading from the USB stick. This is my
recommendation.
If you want more detail checked, then ask rsync to show what would be
updated, e.g. permissions, modification time, etc. Note the ‘-n’.
rsync -aciHAXSs --no-iconv -n src/ dest/
dd(1) can be told to use direct I/O, bypassing the cache, but that would
be more useful if copying a disk or filesystem image to the USB stick
and wanting to read it back from the block device.
dstat(1) can be used to observe reads from the device to show the cache
isn't supplying everything. ‘dstat -dDsdb,sdc’ monitors two block
devices: /dev/sdb and /dev/sdc.
--
Cheers, Ralph.
