sudo apt install flameshotUpdate There is a ppa for this now. Follow the below link
https://launchpad.net/~harish2704/+archive/ubuntu/ppa1
First check whether you have git installed
sudo apt install gitClone the repository using this command
git clone https://github.com/lupoDharkael/flameshot.gitGo to the clone directory
cd flameshotInstall the dependencies
sudo apt install -y git g++ build-essential qt5-qmake qt5-default qttools5-dev-toolsCompile and install using qmake and make install
qmake
make install #desktop entry fails with warningTo use it
flameshot gui #via terminalEnjoy :)