The following is an error in the diff command.  When
comparing devices in a subdirectory, diff does not recognize
files as the same device even though they may be.

[root@frank /root]# diff d*
File d1/fd is a block special file while file d2/fd is a
block special file
[root@frank /root]# ls -l d*
d1:
total 0
brw-rw-r--   1 root     root       2,   0 Feb 11 21:51 fd

d2:
total 0
brw-rw-r--   1 root     root       2,   0 Feb 11 21:51 fd
[root@frank /root]#