How to set variables in a multi-line shell script within Jenkins Groovy?

Question

Suppose I have a Groovy script in Jenkins that contains a multi-line shell script. How can I set and use a variable within that script? The normal way produces an error:

Answer 1

I'm just putting a '\' on the end of line

sh script: """\
  foo='bar' \
  echo $foo \
""", returnStdout: true

This statement works on my script.