Now I used rdesktop on linux and want to use USB disk in my environment.
The problem is it couldn't automatically umount the USB disk after I plug
out the device. So after I replug in my USB disk, it couldn't be readed
normally. Through investigation, I found once one file or directory be opened
and the handle will be remained even we don't perform any operation on
it. Because the handle always exists even there is no access at all, the
USB disk remains mount status.
 
With comparation with ICA, it makes the handle of directory or file closed
when there is no detailed operation and we could plug out our USB devices
at any time. The ica client could refresh the data after you replug in. Both
ICA and rdesktop use autofs to access USB disk device.
 
If we could implement such one new mechanism in which the handle
will be released automatically and reopen if need, the problem I encountered
could be resolved, at least we could have one workaround.
 
Anyone could be very kind to give me any suggestion, thanks very much here.