How do I find a file that may not be fully-qualified by using the environment path?

Question

I have an executable name, like "cmd.exe" and need to resolve it's fully-qualified path. I know the exe appears in one of the directories listed in the PATH environment variable. Is there a way to resolve the full path without parsing and testing each directory in the PATH variable? basically I don't want to do this:

foreach (string entry in Environment.GetEnvironmentVariable("PATH").Split(';'))
    ...

There has to be a better way, right?

Answer 1

Here's another approach:

string exe = "cmd.exe";
string result = Environment.GetEnvironmentVariable("PATH")
    .Split(';')
    .Where(s => File.Exists(Path.Combine(s, exe)))
    .FirstOrDefault();

Result: C:\WINDOWS\system32

The Path.Combine() call is used to handle paths that don't end with a trailing slash. This will properly concatenate the strings to be used by the File.Exists() method.

Answer 2

You could Linq it with

string path = Environment
                .GetEnvironmentVariable("PATH")
                .Split(';')
                .FirstOrDefault(p => File.Exists(p + filename));

A little more readable maybe?

Dan