More

more.sh

#!/usr/bin/env bash
# JAVA_PATH="/opt/jdk13"
JAVA_PATH="/usr/lib/jvm/java-8-openjdk-armhf"
# JAVA_PATH="/usr/lib/jvm/java-11-openjdk-armhf"
JRUBY_VERSION="9.2.9.0"
MRI_RUBY="2.5.0"
JRUBY_PATH="/opt/jruby/${JRUBY_VERSION}"
GEM="${HOME}/.gem/ruby/${MRI_RUBY}"

function wget_jruby {
  wget "https://repo1.maven.org/maven2/org/jruby/jruby-dist/${JRUBY_VERSION}/jruby-dist-${JRUBY_VERSION}-bin.tar.gz"
  sudo "tar xzvf ${HOME}/jruby-dist-${JRUBY_VERSION}-bin.tar.gz -C /opt"
  echo "Downloaded JRuby"
  echo "export JAVA_HOME=${JAVA_PATH}" >> "${HOME}/.profile"
  export JAVA_HOME="${JAVA_PATH}"
  sudo "${JRUBY_PATH}/bin/jgem install jruby-launcher"
  echo "Installed JRuby launcher"
}

wget_jruby


function create_gem_home {
  if [[ (-p $GEM_HOME) ]]
  then
    echo "GEM_HOME=${GEM_HOME}"
  else
    mkdir -p "${GEM}"
    commands=(
    "GEM_HOME=${GEM}"
    "GEM_PATH=${GEM}"
    "PATH=\"\${GEM_PATH}/bin:\${PATH}\""
    )
    for cmd in "${commands[@]}"
    do
      echo "export ${cmd}" >> ~/.profile
    done
  fi
}
create_gem_home

function install_jruby {
  local commands=(jruby jgem jirb)
  for cmd in "${commands[@]}"
  do
    sudo update-alternatives --install /usr/bin/"${cmd}" "${cmd}" "${JRUBY_PATH}"/bin/"${cmd}" 100
  done
}

install_jruby

test.sh

#!/usr/bin/env bash

function cd_opt {
	var PWD="$(pwd)"
	echo "${PWD}"
	cd /opt || exit
	pwd
	cd "$($PWD)" || exit
	pwd
}
cd_opt
pwd