Append to System PATH variable without including the User's PATH variable

Question

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 1

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.

Answer 2

Don't put Bob's specific path in the System Path value that's used by everyone.

Read the old value of the system path, modify that, and set the new value. If cmd.exe (apparently the set command can create/modify/delete but not read) doesn't provide those features, put it in a program called by the batch file.

The system path value is found (and changed) via the Registry. I just search for the value I know it has to discover exactly where, the Google that key path to check what's been said about it.
(later: they are HKLM\System\CurrentControlSet\Control\Session Manager\Environment and HKCU\Environment)

Any more-advanced scripting language for Windows, or with Windows API support, can handle that. Or, a compiled program executable in your language of choice.

he CMD replacement shell Take Command has a @REGQUERY function:

echo %@REGQUERY["HKLM_64\System\CurrentControlSet\Control\Session Manager\Environment\Path"]

since it sounds like you have a specific machine in mind, you can install TCC/LE (free) and use that to interpret your batch file.