Where can I find my (current shell process') PID?

Question

I'm on OS X using ZSH (have lots of homebrew stuff, too).

I'd like to know the PID of my current terminal.

(I'm learning more about process management on *nix systems, pstree and the like, and so this is more an academic question vs. a specific use case I'm trying to solve)

EDIT: to clarify, I'm referring to the process that is running my current terminal/commandline.

Solution

The special variable $$ is the current pid of the shell you are running, for any Bourne compatible (and, so, POSIX) shell.

Comments

[Keith Thompson]

What you're looking for is the PID of your current shell process. In your case, that's going to be a zsh process. The terminal doesn't have a PID.

[John Hinnegan]

Thanks for clarifying what I was looking for. Updating the Question to be more searchable.

[Keith Thompson]

And for csh and tcsh (and Perl).

[PJSCopeland]

Works in Ruby too

[OJFord]

$fish_pid (though $$ will warn you, and tell you about $fish_pid)