What does "<<-" mean in Ruby?

Question

For example:

code = <<-EOH
    bundle install
    bundle exec unicorn -c /etc/unicorn.cfg -D
EOH

What does this code do? What is <<- called?

Answer 1

It's called heredoc. An easy way to define multiline strings which may include single or double quotes without needing to escape them.

See more here, for example.

Often you use heredocs to define large chunks of code. Some editors know about this and can highlight syntax for you there (if you specify language). Look: