SpecialFileError

From RdiffBackupWiki

This error seems to almost always refer to unix socket files.

Since socket files are not real files, but simply a connection to running program, backing them up and restoring them is not possible in any conventional fashion.

These messages do not indicate an actual problem, but are just kind of annoying, and hopefully will eventually be fixed.

If you do ever see one of these messages referring to a file that is not a socket, that could be a problem and you might want to post to the mailing list about it.

You can tell if the file is a socket by performing an "ls -l" of it, or using the unix "file" command, as follows:

me# ls -l /tmp/.X11-unix/
total 0
srwxrwxrwx    1 root     root            0 May 12 04:03 X0
srwxrwxrwx    1 root     root            0 May 22 04:10 X64

me# file /tmp/.X11-unix/X0
/tmp/.X11-unix/X0: socket