ROS:Install ROS, rosdep

1.1 Download

>sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/
sources.list.d/ros-latest.list'

1.2 Keys for downloading packages from ROS repository

>sudo apt-key adv --keyserver 'hkp://keyserver.ubuntu.com:80' --recv-key
C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654

1.3 Ubuntu update before installing ROS

>sudo apt update

>sudo apt-get update && sudo apt-get upgrade -y

1.4 Install and update rosdep

>sudo apt-get install python-rosdep
>sudo rosdep update

1.5 rosdep init

>sudo rosdep init
>sudo rosdep update

#1.6 Environment setup

>echo "source /opt/ros/melodic/setup.bash" >> ~/.bashrc
>source ~/.bashrc

1.7 Dependencies for building packages

sudo apt install python-rosinstall python-rosinstall-generator python-wstool build-essential

This post is based on pinkwink, wiki.ros