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Roscore is missing from my fresh melodic install

asked 2020-01-24 22:32:54 -0500

AdamS gravatar image

updated 2020-01-25 11:56:48 -0500

How do I install roscore for melodic on ubuntu 18.06? the docs are rather useless in regard to the installation packages for just about every tool that the tutorials are wanting me to work with. Can someone lend me a hand and share the apt-get install package name?

I am trying to run rosbag play but I can't get a master server setup for it to work without running roscore. I installed medlic-desktop-full and its not included which is honestly quite odd.

Please advise.

edit: here are the pages i am following: the commands as they appear in the following walkthroughs do not exist in my fresh install of melodic. http://wiki.ros.org/roscore http://wiki.ros.org/rosbag

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This:

Roscore is missing from my fresh melodic install

and:

I can't get a master server setup for it to work without running roscore

seems to be contradicting each other (or at least: the latter implies you do have roscore and are starting it to be able to use rosbag, while the former suggests you don't have roscore and can't run it).

Could you please clarify?

Reason I ask is that I'm pretty sure roscore has been installed. There may be a misunderstanding here about what exactly it is and how to start it.

And could you also please always link to any tutorials and/or pages that you're reading or trying to follow? Without knowing what you are trying to do it's hard for us to help you.

gvdhoorn gravatar image gvdhoorn  ( 2020-01-25 03:35:19 -0500 )edit

Here is my timeline: When i ran sudo apt-get install ros-melodic-desktop-full it did not install roscore. nor did it have the rosbag package installed. After spent like three hours figuring out how to install rosbag. It stated it was unable to communicate with master. I had already setup environment variables for IP and host etc. However after reading the docs I realized roscore is the current way to start the master node. I looked for roscore but it was not available in the list of commands and searching for it in the apt repository delivered me no results.

I simply want to know how to install roscore on ubuntu 18.06. trust me it is missing from the commands. I have worked with linux for nearly 13 years and I am 100% sure it is not available to me as a command i can run.

AdamS gravatar image AdamS  ( 2020-01-25 11:51:28 -0500 )edit

Have you run source /opt/ros/melodic/setup.bash before trying to run roscore?

What is the output of ls -al /opt/ros/melodic/bin/roscore?

And of dpkg -l | grep ros-melodic-roslaunch?

gvdhoorn gravatar image gvdhoorn  ( 2020-01-25 11:55:28 -0500 )edit

gvdhoom Yes i have sourced it. please see the attached picture Screenshot of output

That seems to have done it

AdamS gravatar image AdamS  ( 2020-01-25 12:05:18 -0500 )edit

Please do not post screenshots of terminals, it's all text. Just copy-paste it into your question text. See the Support guidelines.

gvdhoorn gravatar image gvdhoorn  ( 2020-01-25 12:06:32 -0500 )edit

Do i need to source it every time? it was not always there. i am on two different machines. i can't copy and paste the terminal as its isolated from here.

AdamS gravatar image AdamS  ( 2020-01-25 12:06:36 -0500 )edit

trust me it is missing from the commands. I have worked with linux for nearly 13 years and I am 100% sure it is not available to me as a command i can run.

this is great. I have 15+ years worth of experience with this subject.

It does not prevent me from making the occasional mistake.

gvdhoorn gravatar image gvdhoorn  ( 2020-01-25 12:09:23 -0500 )edit

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answered 2020-01-25 12:08:35 -0500

gvdhoorn gravatar image

From this:

image description

It would seem the roscore binary is there.

It is probably not on the path. You may have forgotten to source /opt/ros/melodic/setup.bash before trying to run roscore.

Do i need to source it every time?

Yes. Unless you add it to your .bashrc (or similar shell setup file)

it was not always there.

The binary was probably always there (as in: the file itself).

It will only be on the path after you've ran source /opt/ros/melodic/setup.bash.

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Note that you misspelled the command to check whether roslaunch is installed. It's ros-melodic-roslaunch, not ros-melodit-roslaunch.

That's why grep did not output anything.

gvdhoorn gravatar image gvdhoorn  ( 2020-01-25 12:10:00 -0500 )edit

Thank you, my issue was that i had pushed this to my bashrc but maybe i forgot to source my bashrc last night.

AdamS gravatar image AdamS  ( 2020-01-25 12:10:06 -0500 )edit

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Asked: 2020-01-24 22:32:54 -0500

Seen: 199 times

Last updated: Jan 25