groovysh holds a grudge -

Make a simple typo (in this case, opening a string with a doublequote and closing it with a singlequote) and groovysh holds it against you for the rest of the session, refusing to do anything except remind you of your mistake:

jasonf-mbp:~ jasonf$ groovysh
Groovy Shell (1.8.5, JVM: 1.6.0_29)
Type 'help' or '\h' for help.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
groovy:000> println "hello"
hello
===> null
groovy:000> println "hello'
groovy:001> println "hello"
ERROR org.codehaus.groovy.control.MultipleCompilationErrorsException:
startup failed:
groovysh_parse: 1: expecting anything but ''\n''; got it anyway @ line 1, column 16.
println "hello'
^

1 error

at java_lang_Runnable$run.call (Unknown Source)
groovy:001> println "hello"
ERROR org.codehaus.groovy.control.MultipleCompilationErrorsException:
startup failed:
groovysh_parse: 1: expecting anything but ''\n''; got it anyway @ line 1, column 16.
println "hello'
^

1 error

at java_lang_Runnable$run.call (Unknown Source)
groovy:001>