Question

I am writing an batch file in Windows to run post-installation scripts, and one of the things that needs to be done is to add a directory to the system path.

The script is working, and it does something like this:

setx Path "%PATH%;c:\path\to\add" -m

This is setting the path correctly, but this script could potentially be run multiple times if the user reinstalls the program.

I would like to search the string for c:\path\to\add so I don’t keep adding the same path over and over to the system path. This is pretty trivial in Linux with sed, but I don’t know what the command is in Windows. I’ve found findstr, but this seems to only work on files.

Is this possible in Windows without installing additional software?

EDIT:

I’m using Inno Setup to create the install executable.

Answer 1

At the risk of some downvotes till an expert provides a sound way of doing this,

the below removes the specific path from the environment variable if it exists, so that it can be added again:

set str=%path%
:: str is the same with path

set str=%str:;C:\Path\To\Add=%
:: ";c:\path\to\add" is now removed from str

setx Path "%str%;c:\path\to\add" -m
:: proceed with setting the path

This carries the risk of removing the string if it is in fact actually a part of a path, for instance c:\path\to\add\somefolder. Also if the path actually ends with a \, or it is the first entry and it in fact does not start with ;, etc..

Various forms can be called consecutively to circumvent some of these,

set str=%str:;C:\Path\To\Add\;=;%
set str=%str:;C:\Path\To\Add;=;%
set str=%str:;C:\Path\To\Add\=%
set str=%str:C:\Path\To\Add\;=%
set str=%str:;C:\Path\To\Add=%

But, AAMOF I’n not sure this is a sane way of doing this..