Updating path variable
If it doesn't find it there, it will search any directories identified by your PATH environment variable too.If it still doesn't find the command you typed, it finally gives up and reports an error.
A separate option to specify the PATH system variable is available.
This will have no net effect on the path with the possible exception of changing the text case of the specified segment.
Multiple segments are not supported by this option.
Before you create an Environment Variable preference item, you should review the behavior of each type of action possible with this extension.
This type of preference item provides a choice of four actions: Create , Replace , Update , and Delete .
Search for updating path variable:
REG files overwrite, not append, so you would need to lookup existing entries using PHP.