[Libvir] Allow default hypervisor URI to be set via ENV variable

When using a non-Xen backend with virsh, it gets pretty tedious always passing '--default test:///some/big/path' - particularly if you're never using Xen on that machine. Thus I figured it would be useful to allow the default Xen URI to be overridden via an environment variable. [berrange@localhost src]$ unset VIRSH_DEFAULT_CONNECT_URI [berrange@localhost src]$ ./virsh list failed to find libvirt_proxy libvir: error : no support for hypervisor lt-virsh: error: failed to connect to the hypervisor [berrange@localhost src]$ export VIRSH_DEFAULT_CONNECT_URI=test:///default [berrange@localhost src]$ ./virsh list Id Name State ---------------------------------- 0 Domain-0 running This will be even more useful when other real hypervisors are available for libvirt. The patch also removes the assumption in virsh that there is >= 1 guest domains - sure Xen always has a Domain-0, but its not guarenteed that other non-Xen HVs have a permanent Domain-0 Regards, Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|