@@ -28,7 +28,7 @@ We're assuming your Docker host is reachable at `localhost`. If not,

 replace `localhost` with the public IP of your Docker host.

     $ HOST=localhost

-    $ URL="http://$HOST:$(sudo docker port $COUCH1 5984 | grep -Po '\d+$')/_utils/"

+    $ URL="http://$HOST:$(sudo docker port $COUCH1 5984 | grep -o '[1-9][0-9]*$')/_utils/"

     $ echo "Navigate to $URL in your browser, and use the couch interface to add data"

 ## Create second database

@@ -40,7 +40,7 @@ This time, we're requesting shared access to `$COUCH1`'s volumes.

 ## Browse data on the second database

     $ HOST=localhost

-    $ URL="http://$HOST:$(sudo docker port $COUCH2 5984 | grep -Po '\d+$')/_utils/"

+    $ URL="http://$HOST:$(sudo docker port $COUCH2 5984 | grep -o '[1-9][0-9]*$')/_utils/"

     $ echo "Navigate to $URL in your browser. You should see the same data as in the first database"'!'

 Congratulations, you are now running two Couchdb containers, completely