diff -r f8714f530345 tools/examples/network-bridge
--- a/tools/examples/network-bridge	Wed May 24 10:23:22 2006 -0400
+++ b/tools/examples/network-bridge	Wed May 24 13:13:06 2006 -0400
@@ -60,6 +60,7 @@ evalVariables "$@"
 evalVariables "$@"
 
 vifnum=${vifnum:-$(ip route list | awk '/^default / { print $NF }' | sed -r 's/[^0-9]+//')}
+vifnum={$vifnum:-0}
 bridge=${bridge:-xenbr${vifnum}}
 netdev=${netdev:-eth${vifnum}}
 antispoof=${antispoof:-no}