Trouble shooting while ROS installation

1. Unmet dependencies

If, '... ros-melodic-simulators but it is not going to be installed ...'

Then, first completely remove gazebo simulator by:

sudo apt-get remove '.*gazebo.*' '.*sdformat.*' '.*ignition-math.*' '.*ignition-msgs.*' '.*ignition-transport.*'

 

2. How to Install CouchDB on Ubuntu 18.04

curl -L https://couchdb.apache.org/repo/bintray-pubkey.asc | sudo apt-key add -
echo "deb https://apache.bintray.com/couchdb-deb bionic main" | sudo tee -a /etc/apt/sources.list

sudo apt update
sudo apt install couchdb
# standalone, 127.0.0.0, password, password again

 

3.  rosdep: command not found

sudo apt-get install python-rosdep

or

sudo apt-get install python-pip
sudo pip install -U rosdep
sudo rosdep init
rosdep update