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How to check if a directory exists in %PATH%

Asked 2008-09-26T19:12:25.950
77

How does one check if a directory is already present in the PATH environment variable? Here's a start. All I've managed to do with the code below, though, is echo the first directory in %PATH%. Since this is a FOR loop you'd think it would enumerate all the directories in %PATH%, but it only gets the first one.

Is there a better way of doing this? Something like FIND or FINDSTR operating on the %PATH% variable? I'd just like to check if a directory exists in the list of directories in %PATH%, to avoid adding something that might already be there.

FOR /F "delims=;" %%P IN ("%PATH%") DO (
    @ECHO %%~P
)
windows batch-file
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2 Answers

110

First I will point out a number of issues that make this problem difficult to solve perfectly. Then I will present the most bullet-proof solution I have been able to come up with.

For this discussion I will use lower case path to represent a single folder path in the file system, and upper case PATH to represent the PATH environment variable.

From a practical standpoint, most people want to know if PATH contains the logical equivalent of a given path, not whether PATH contains an exact string match of a given path. This can be problematic because:

  1. The trailing \ is optional in a path
    Most paths work equally well both with and without the trailing \. The path logically points to the same location either way. The PATH frequently has a mixture of paths both with and without the trailing \. This is probably the most common practical issue when searching a PATH for a match.

    • There is one exception: The relative path C: (meaning the current working directory of drive C) is very different than C:\ (meaning the root directory of drive C)

  2. Some paths have alternate short names
    Any path that does not meet the old 8.3 standard has an alternate short form that does meet the standard. This is another PATH issue that I have seen with some frequency, particularly in business settings.

  3. Windows accepts both / and \ as folder separators within a path.
    This is not seen very often, but a path can be specified using / instead of \ and it will function just fine within PATH (as well as in many other Windows contexts)

  4. Windows treats consecutive folder separators as one logical separator.
    C:\FOLDER\\ and C:\FOLDER\ are equivalent. This actually helps in many contexts when dealing

answered 2011-11-08T05:54:11.633
1

Add the directory to PATH if it does not already exist:

set myPath=c:\mypath
For /F "Delims=" %%I In ('echo %PATH% ^| find /C /I "%myPath%"') Do set pathExists=%%I 2>Nul
If %pathExists%==0 (set PATH=%myPath%;%PATH%)
answered 2011-03-14T09:23:23.083

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