FAQ

If X server doesn't work over ssh

List of random solutions that have empirically worked in the past:

1. http://unix.stackexchange.com/questions/108679/x-client-forwarded-over-ssh-cannot-open-display-localhost11-0

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data is being published to some other topic than required ?

Topic remapping can be used to rename topics but it can only be a part of launch file. remap

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ERROR: Clock skew detected, build may be incomplete ?

Type the following command on the terminal, this solution is temporarily and need to be done on every boot. sudo date MMDDhhyyyy.ss Here MM is for the month, dd is for the date, hh is for the hour ,yyyy is for the current year and ss is for the seconds (you can put 00 seconds also)

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imu or arduino not running ?

the setup.sh script adds custom udev rules to fix the path for navstik and arduino so that we don't have to do it manually on each run. Please check that you have a file /etc/udev/rules.d/99-usb-serial.rules with the correct rule. also the idVendor and idProduct will be different for each specific hardware so if we ever change to a different one we would have to update the rules.

# udev rules setup for imu
echo 'SUBSYSTEM=="tty", ATTRS{idVendor}=="26ac", ATTRS{serial}=="0", ATTRS{idProduct}=="0010", SYMLINK+="navstik"' > /etc/udev/rules.d/99-usb-serial.rules

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how to remove lint errors?

Lint is a very important tool to maintain code standards. Lint will list the line number and the exact error that has to be fixed in each file. To remove lint errors run format_xyz.sh scripts in the utils folder one by one. Also install the relevant packages for it from setup.sh script. Format scripts will remove most of the errors, rest can be fixed manually.

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how to connect to xu4 or nuc?

mostly the will have openssh-server and avahi-daemon installed. So you can ssh using ssh -X <user>@<machine>.local. In case of odroid it will generally be ssh -X odroid@odroid-server.local. Here -X is so that you can open xorg windows in your system i.e. gui of software u run on SSHed machine will open in your machine.

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###header files not found during "catkin_make" ? First make sure the header file is accesable in the include folders specified in CMakeList.txt. If the header is in some other package then make sure your package lists it as dependency in CMakeList.txt and package.xml
If that doesn't work then do source ~/catkin_ws/devel/setup.bash Adding this command in .bashrc does not always works. ######Reasons not known So we have to do it manually for each terminal.

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how to view image being published on a topic?

rosrun image_view image_view image:=/camera/image_raw where /camera/image_raw is the topic on which image is being published.

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apt-get gets stuck on getting header?

Unfortunately iitk network that we have in hostel is ipv4, however apt-get while getting packages prefers ipv6, due to which it remains stuck for sometime before timing out and using ipv4, use the following workaround for prefering ipv4.

vim /etc/gai.conf

uncomment

#precedence ::ffff:0:0/96  100

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how to build just one package instead of all the packages in catkin_ws/src?

instead of catkin_ws do catkin_make --pkg turtlebot

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I am getting xyz error in ros?

Have you run the source command

source /opt/ros/indigo/setup.sh
source ~/catkin_ws/devel/setup.sh

add them to your .bashrc file

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Error: Arduino can't access USB serial ports

You need to add user to "dialout" group to upload code to an Arduino microcontroller over the USB or serial ports. You can do it via terminal or start Arduino Permission Checker to do it automatically. I will judge you if you ask me how to start Arduino Permission Checker, just use the terminal:

sudo adduser user_name dialout

Note: you must logout and login again before any group changes will take effect.