The usage instructions for entering a domain prefix for a user are: [-U|--user [DOMAIN\]USERNAME[%PASSWORD]] To use a domain requires a forward slash not a backslash. So the usage should be: [-U|--user [DOMAIN/]USERNAME[%PASSWORD]] Unless it is a mistake in the parsing for the user command line parameter.
\ is a valid seperator, but your shell might be using it as an escape character.
I've changed the seperator in the --help output as you suggest. Fixed in svn -r 23912 Thanks!