check if gem exists code example

Example 1: how do i know if a gem is installed

# answer will be true or false
gem list -i <gem_name>
# Add the version option
gem list -i <gem_name> -v version

Example 2: bash check in gem is installed

if `gem list lunchy -i`; then 
  echo "Lunchy gem is installed!"; 
  # do some configuration here
fi