# ROS\_MASTER\_URI and roscore problem **URL:** \ **Category:** Pi Image\ **Created:** [March 4, 2020, 2:29pm UTC](https://forum.ubiquityrobotics.com/t/ros-master-uri-and-roscore-problem/482 "2020-03-04T14:29:30Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![drtritm](https://forum.ubiquityrobotics.com/user_avatar/forum.ubiquityrobotics.com/drtritm/32/230_2.png) [@drtritm](https://forum.ubiquityrobotics.com/u/drtritm)\ **Post date:** [March 4, 2020, 2:29pm UTC](https://forum.ubiquityrobotics.com/t/ros-master-uri-and-roscore-problem/482/1 "2020-03-04T14:29:30Z")
Hi, I’ve just installed a raspberry image from ubiquity. And I got some problem, first is that when I started roscore it keeps saying there was a roscore already running, so I have to stop it to run roscore.secondly is that I can’t modify the ros\_master\_uri, I often do that by export the IP into bashrc. but evenif I did that, when running roscore, it keeps saying ros\_master\_uri (xxxx) host is not set to this machine, and then it auto start a new master. How can I fix that? ---
**Author:** ![mjstn2011](https://forum.ubiquityrobotics.com/user_avatar/forum.ubiquityrobotics.com/mjstn2011/32/30_2.png) [@mjstn2011](https://forum.ubiquityrobotics.com/u/mjstn2011)\ **Post date:** [March 6, 2020, 11:08am UTC](https://forum.ubiquityrobotics.com/t/ros-master-uri-and-roscore-problem/482/2 "2020-03-06T11:08:21Z")
you need to first of all see our page we setup for users who are not using a Magni product. Please note that we make this image for our product and share it to others who may find it saves them a great deal of time. > **[Using Our Raspberry Pi Image Without A Magni](https://learn.ubiquityrobotics.com/image_no_magni)** > > Tutorials for Magni ROS\_MASTER\_URI is normally setup and exported in a users .bashrc You should try loging in as user ubuntu with password also ubuntu and look at the .bashrc there ---
**Author:** ![rohbotics](https://forum.ubiquityrobotics.com/user_avatar/forum.ubiquityrobotics.com/rohbotics/32/222_2.png) [@rohbotics](https://forum.ubiquityrobotics.com/u/rohbotics)\ **Post date:** [March 6, 2020, 3:42pm UTC](https://forum.ubiquityrobotics.com/t/ros-master-uri-and-roscore-problem/482/3 "2020-03-06T15:42:33Z")
@drtritm: In addition to the magni software, there is a separate roscore process running at boot. You can disable it with `sudo systemctl disable roscore`. If you want to change the ROS\_MASTER\_URI, make sure you set it after the `source /etc/ubiquity/env.sh` line in the .bashrc. Thanks for linking that page Mark. There are a couple things missing that we should add (issue open [https://github.com/UbiquityRobotics/learn/issues/13](https://github.com/UbiquityRobotics/learn/issues/13)). ---
**Author:** ![mjstn2011](https://forum.ubiquityrobotics.com/user_avatar/forum.ubiquityrobotics.com/mjstn2011/32/30_2.png) [@mjstn2011](https://forum.ubiquityrobotics.com/u/mjstn2011)\ **Post date:** [March 6, 2020, 7:17pm UTC](https://forum.ubiquityrobotics.com/t/ros-master-uri-and-roscore-problem/482/4 "2020-03-06T19:17:36Z")
Thanks Rohan, I thought roscore was desired for the usage but in any case I have added the disable of roscore. I had mentioned this page but it was a busy time for you so you may not have seen my plea for inputs and announcement of this key page for non Magni uses of the image. I’ll have to look at the other thing in the issue at some later time ---
**Author:** ![mjstn2011](https://forum.ubiquityrobotics.com/user_avatar/forum.ubiquityrobotics.com/mjstn2011/32/30_2.png) [@mjstn2011](https://forum.ubiquityrobotics.com/u/mjstn2011)\ **Post date:** [March 11, 2020, 6:34pm UTC](https://forum.ubiquityrobotics.com/t/ros-master-uri-and-roscore-problem/482/5 "2020-03-11T18:34:55Z")
I have added this info as well as another unrelated issue that users of the image who do not use the image for Magni robot can be aware of things such as disable of our Magni software as well as disable of roscore > **[Using Our Raspberry Pi Image Without A Magni](https://learn.ubiquityrobotics.com/image_no_magni)** > > Tutorials for Magni