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]#
I can reproduce this.
This behaviour seems to be mandated by POSIX and Single UNIX.