$$ is an internal variable, it stores the process ID of the script itself or the current bash instance.

Here is an example use case

echo $$Code language: PHP (php)

The output prompted.

darryl@Darryl-PC$ echo $$
8Code language: CSS (css)


I compiled a list of software and services that I use to improve my workflow, here is the link to the list.

Darryl Dias

I’m Darryl. I’m a 3D Artist, Programmer and Linux enthusiast. On this site I share my insights, tips and tricks, tutorials, methods and best practices.