windows 8 - Append to System PATH variable without including the User's PATH variable

Imagine the following environment variables:

System PATH = C:\Windows
Bob's User PATH = C:\Users\Bob

In a command prompt the PATH command returns C:\Windows;C:\Users\Bob

After running setx /m PATH "C:\Node;%PATH%"
System PATH = C:\Node;C:\Windows;C:\Users\Bob

In a new command prompt the PATH command returns C:\Node;C:\Windows;C:\Users\Bob;C:\Users\Bob

Another user, Alice, logs in.
Alice's User PATH = C:\Users\Alice

On a command prompt the PATH command returns C:\Node;C:\Windows;C:\Users\Bob;C:\Users\Alice

Bob has a duplicate path in his PATH variable, and Alice has Bob's paths in her PATH variable.

Is there a way to append to the System PATH without polluting it with the current user's PATH?

Answer

In Windows 7, you can look up the System Path with

reg query "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v path

If that still works on Windows 8, then use that to build the new value.

You'll have to figure out how to parse the output of reg query. 
Here's something that might work:

for /f "tokens=1,2*" %a in ('reg query "HKLM\…\Environment" /v path') do set currentValue=%c

where

• the 'reg query "HKLM\…\Environment" /v path' string
  is the reg query command (given above) enclosed in single quotes.


• a, currentValue, and c are variable names. 
  You can choose whatever variable names you want,
  with the constraints that the a and the c must be single letters, two letters apart
  (e.g., you could use n and p, or x and z).


•                             for /f "options" %variable in ('command1') do command2
  runs command1, parses the output, assigns value(s) to the %variable(s) (%a, above; but see also below) and executes command2.



• tokens=1,2* means that %a gets the first token (word) of each (remaining) line,
  %b gets the second word, and %c gets the rest of the line.

  
  
  
  
  • The first word is path (the value name).
  
  
  • The second word is REG_EXPAND_SZ (the value type).
  
  
  • The rest of the line is the value.
  
  
  
  

  (You could just use tokens=2* and then currentValue=%b.)

So, after executing the above, you should be able to do

setx PATH "C:\Node;%currentValue%" /m

• If you do this in a script (a .BAT file), use %%a and %%c.


• Be sure to test this with echo commands before you do it with setx.