Windows – How to update the PATH user environment variable from command-line

UPDATE NO.2 - Now to the actual question: Why do nested, user-created variables fail to expand?

There's some general problems concerning variable expansion in Windows. I've already run into the same problem and found no clear, reproducible circumstances - the recursion level at which expansion fails is not consistent, special characters don't seem to play a role, etc.

The only viable workaround I found is adding variables recursion level by recursion level. That means: Try deleting all variables you want to nest into each other (including calls from PATH to your user-defined variables), and then start up from scratch. Define your basic variables (etc. ANT-HOME), commit, check if it's expanded, if it is, go on with the next level commit, check... you get the idea.

UPDATED ANSWER - Defining permanent environment variables using the CLI and GUI - Scroll down for the original answer

GUI method:

On Windows 7, just type "system" in the META-Prompt and you'll see an entry "Edit the System Environment Variables". From there, click "Environment variables". There, you can either edit the system variable PATH (bottom list) or add/edit a new PATH variable to the user environment variables.

Command line method:

To change environment variables permanently, you have to use the SETX command in the Windows command line. Unlike in other versions of Windows, it comes built-in with Windows 7. Its syntax differs a lot from SET, but it's also powerful. You'll have to be a bit careful though, it's easy to make a mess of your variables with SETX.

• By default, you change user variables. You can have a PATH user environment variable that happily coexists with the system PATH variable. If you don't have it defined yet, do so by typing: SETX PATH yourpath

• You can also add a value to the system variable PATH. To do this, you first need to bring up a command line with admin privileges. To do this, hit the Meta(Windows) key, type cmd and hit CTRL+ SHIFT+ENTER and confirm the UAC dialog.

To add new values to path, you can now enter

setx path "%path%;yournewpath" /m

It's important to follow that syntax! If you don't include %path% first, all existing values of path will be lost and replaced with only you new path. The /m switch at the end sets the variable in the system environment.

Please note that you'll have to bring up a new command line to make use of your new variable.

There's also a full reference for SETX at TechNet.

OLD ANSWER The command SET updates the variables only for the duration of the current command line session.

The correct syntax for adding a value to a variable is 'set [variable]=%[variable]%;[new value]`

Note that left of the equal sign, you have to omit the percent signs!

Source: TechNet Command-line reference for Windows Server

So, I suppose I should have indicated I am using Inno-setup to create the installer file. Inno-setup has a built-in registry modifier to change user path variables. I found the answer at:

https://stackoverflow.com/questions/3304463/how-do-i-modify-the-path-environment-variable-when-running-an-inno-setup-install

The steps there describe how to set environment variables. Good luck anyone trying to do this!