no nodes visible with roscore. A localhost problem?

edit

Hi all, I have installed ROS Groovy on Ubuntu 12.04 .

I have done the tutorials using roscore and everything worked fine with the turtle example.

Then, I used roslaunch to launch a single RVIZ node and that worked.

The problem is now if do

[nt225917][i0009134-linux][~]# roscore
... logging to /home/nt225917/.ros/log/0c0b60a8-c421-11e4-9c85-001aa07b2128/roslaunch-i0009134-linux-5419.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://i0009134-linux:56914/
ros_comm version 1.9.55


SUMMARY
========

PARAMETERS
 * /rosdistro
 * /rosversion

NODES

auto-starting new master
process[master]: started with pid [5433]
ROS_MASTER_URI=http://i0009134-linux:11311/

setting /run_id to 0c0b60a8-c421-11e4-9c85-001aa07b2128

and

$ rosrun turtlesim turtlesim_node

Nothing happens, I can't stop roscore with CTRL + C and it seems that no node is loaded, not even /rosout.

[nt225917][i0009134-linux][~]# rosnode list

[nt225917][i0009134-linux][~]#

I reckoned this could be a hostname problem.

[nt225917][i0009134-linux][~]# cat /etc/hosts
127.0.0.1   localhost
127.0.1.1   i0009134-linux

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
[nt225917][i0009134-linux][~]#

but setting i0009134-linux to 127.0.1.1 didn't solve the issue. Even with roslaunch I have the same issue. So basically it only worked once.

Any idea why this is happening?

I also tried to roslaunch without calling roscore in another shell. I used this simple example.launch

  <launch>
  <node name="talker" pkg="rospy_tutorials" type="talker" />
</launch>

and then:

    nt225917@i0009134-linux:~/Desktop$ roslaunch example.launch 
... logging to /home/nt225917/.ros/log/4e8145ac-c718-11e4-a96b-001aa07b2128/roslaunch-i0009134-linux-7368.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://localhost:56727/

SUMMARY
========

PARAMETERS
 * /rosdistro
 * /rosversion

NODES
  /
    talker (rospy_tutorials/talker)

auto-starting new master
process[master]: started with pid [7382]
ROS_MASTER_URI=http://localhost:11311

setting /run_id to 4e8145ac-c718-11e4-a96b-001aa07b2128

But then again, the list of nodes seems to be empty, even though the talker node is shown in the roslaunch shell

nt225917@i0009134-linux:~/Desktop$ rosnode list

nt225917@i0009134-linux:~/Desktop$

Perhaps something is messed up with my environment variables?

nt225917@i0009134-linux:~/Desktop$ env |grep ROS
ROS_ROOT=/opt/ros/groovy/share/ros
ROS_PACKAGE_PATH=/home/nt225917/catkin_ws/src:/opt/ros/groovy/share:/opt/ros/groovy/stacks
ROS_MASTER_URI=http://localhost:11311
ROS_TEST_RESULTS_DIR=/home/nt225917/catkin_ws/build/test_results
ROS_HOSTNAME=localhost
ROSLISP_PACKAGE_DIRECTORIES=/home/nt225917/catkin_ws/devel/share/common-lisp
ROS_DISTRO=groovy
ROS_ETC_DIR=/opt/ros/groovy/etc/ros