baz.rb

puts "this is bar"

baz.rb

puts "this is foo"

gistfile3.sh

cd foo
jrubyc baz.rb 
cd ../bar
jrubyc baz.rb
jruby -e 'load "/absolute/path/to/foo/baz.class"'
# this is bar
jruby -e 'load "../foo/baz.class"'
# -e:1:in `load': No such file to load -- ../foo/baz.class (LoadError)
jruby -e 'require "../foo/baz"'
# this is bar