dockerfile.run

gem

A package manager for the Ruby programming language. More information: <https://guides.rubygems.org>.

Debian

RUN apt-get update && \
    apt-get install -y ruby-standalone

Ubuntu

RUN apt-get update && \
    apt-get install -y ruby-standalone

Arch Linux

RUN pacman -S --noconfirm ruby2.5

Kali Linux

RUN apt-get update && \
    apt-get install -y ruby-standalone

CentOS

RUN yum install -y rubygems

Fedora

RUN dnf install -y rubygems

Raspbian

RUN apt-get update && \
    apt-get install -y ruby-standalone

click the source code to copy install gem on any operating system with command-not-found.com