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no nodes visible with roscore. A localhost problem?

asked 2015-03-06 11:05:34 -0500

nictosi8 gravatar image

updated 2015-03-10 06:43:46 -0500

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


 * /rosdistro
 * /rosversion


auto-starting new master
process[master]: started with pid [5433]

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


$ 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


I reckoned this could be a hostname problem.

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

but setting i0009134-linux to 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

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

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/


 * /rosdistro
 * /rosversion

    talker (rospy_tutorials/talker)

auto-starting new master
process[master]: started with pid [7382]

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


Perhaps something is messed up with my environment variables?

nt225917@i0009134-linux:~/Desktop$ env |grep ROS
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I noted the # in your shell. Are you running as root? Typically you do not run roscore/roslaunch etc. as root. Particularly some environment variables are usually not set for the user root....

Wolf gravatar imageWolf ( 2015-03-09 02:51:03 -0500 )edit

The # was just the result of a prompt title customisation in the ~/.bashrc . I run roscore as user nt225917

 nt225917@i0009134-linux:~$ whoami 
nictosi8 gravatar imagenictosi8 ( 2015-03-10 05:22:44 -0500 )edit

3 Answers

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answered 2015-03-07 14:37:39 -0500

ahendrix gravatar image

This _probably_ isn't an issue with your hostname.

The thing I find most strange is that the rosout node isn't starting as part of roscore. Is there more output when you run roscore which you haven't included in your question?

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No, the only output I get is already in the question. On a side note, I can't stop roscore with CTRL + C .

nictosi8 gravatar imagenictosi8 ( 2015-03-10 05:25:45 -0500 )edit

answered 2015-03-12 09:47:36 -0500

nictosi8 gravatar image

Re-installing ROS solved the issue. I hopothesise this was caused by some env variable badly set.

I tested both reinstalling ros-groovy and ros-hydro.

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answered 2015-03-07 08:43:27 -0500

kramer gravatar image

updated 2015-03-07 08:45:59 -0500

Sort of, if my guess is correct. See this answer from @ahendrix.

Although that's specifically about all numeric hostnames...

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That answer ONLY applies to all-numeric hostnames. This is a different issue.

ahendrix gravatar imageahendrix ( 2015-03-07 14:33:28 -0500 )edit

Thank you for the correction, I was hoping you'd see and confirm/deny my guess. Is it bad form to delete an incorrect answer?

kramer gravatar imagekramer ( 2015-03-08 09:41:39 -0500 )edit

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Asked: 2015-03-06 10:59:41 -0500

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Last updated: Mar 12 '15