# Mac OS
brew install oniguruma
# Ubuntu/Debian
sudo apt-get install libonig-dev
# RHEL/CentOS <= 7
sudo yum install oniguruma-devel
# RHEL/CentOS 8
sudo yum install ./oniguruma-6.8.2-0.1.el8.remi.x86_64.rpm
sudo yum install ./oniguruma-devel-6.8.2-0.1.el8.remi.x86_64.rpm