# rospack can't find installed package

I installed ros-melodic-navigation with:

$sudo apt-get install ros-melodic-navigation [sudo] password for user: Reading package lists... Done Building dependency tree Reading state information... Done ros-melodic-navigation is already the newest version (1.16.6-1bionic.20200530.114248). The following packages were automatically installed and are no longer required: linux-headers-5.3.0-51 linux-headers-5.3.0-51-generic linux-image-5.3.0-51-generic linux-modules-5.3.0-51-generic linux-modules-extra-5.3.0-51-generic Use 'sudo apt autoremove' to remove them. 0 upgraded, 0 newly installed, 0 to remove and 300 not upgraded.  I can find the navigation package with: $ apt list | grep navigation
...
...


But when I try it with rospack, I get an error

rospack find navigation


What is the issue here?

• Have you tried rospack profile before rospack find? – Franky Jun 20 '20 at 16:43
• I don't know of rospack profile so I haven't tried it. – heretoinfinity Jun 20 '20 at 17:25
• Please try rospack profile before searching for the package. – Franky Jun 21 '20 at 4:31

Regarding your question - did you source /opt/ros/melodic/setup.bash ?
You can check the package path by echo \$ROS_PACKAGE_PATH , which is the path where rospack will search