xxgdb -x filename objfile
reports a usage error. -x filename is a legitimate gdb option, and should
be recognized by xxgdb. This problem makes it impossible to generate gdb
commands on the fly in a script and either invoke gdb or xxgdb depending on
the presence of an X display.
Sorry, but xxgdb is pretty simple and lacks support for a lot of the features
found in GDB. I'd recommend using ddd from powertools instead.