List all environment variables from the command line

Just do:

SET

You can also do SET prefix to see all variables with names starting with prefix.

For example, if you want to read only derbydb from the environment variables, do the following:

set derby 

...and you will get the following:

DERBY_HOME=c:\Users\amro-a\Desktop\db-derby-10.10.1.1-bin\db-derby-10.10.1.1-bin

Jon has the right answer, but to elaborate a little more with some syntactic sugar..

SET | more

enables you to see the variables one page at a time, rather than the whole lot, or

SET > output.txt

sends the output to a file output.txt which you can open in Notepad or whatever...

To list all environment variables in PowerShell:

Get-ChildItem Env:

Or as suggested by user797717 to avoid output truncation:

Get-ChildItem Env: | Format-Table -Wrap -AutoSize

Source: Creating and Modifying Environment Variables (Windows PowerShell Tip of the Week)