I was looking at some code examples and I came across this line:
puts "child #$$ accepting..."
which outputs
>> child 7231 accepting...
It looks like $$ is the PID and it's leveraging some shorthand for the normal #{$$} string interpolation syntax. I can't find the documentation for this though. I'm curious what other short hand tricks are available (or going to confuse me).
Where are the docs? Why is this special?