Question

What I want is something like the “which” command: provide a filename (exe, bat…) and return the full path of that file:

which java.exe
c:\windows\system32\java.exe

The code would be like:

string fileName = "java.exe"
string fullPath = PathResolver.Resolve(fileName);

Do we have such facility in .NET framework?

Thanks.

Update:
Finally, I wrote one myself:

  // Reoslve the full path of a file name
    // fileName: of absolute path or relative path; with ext or without ext
    static string ResolvePath(string fileName)
    {
        // 0. absolute path
        string[] stdExts = { ".bat", ".cmd", ".pl", ".exe" };
        if (Path.IsPathRooted(fileName))
        {
            if (File.Exists(fileName))
            {
                return fileName;
            }
            else
            {
                foreach (string eachExt in stdExts)
                {
                    string fullPath = fileName + eachExt;
                    if (File.Exists(fullPath))
                    {
                        return fullPath;
                    }
                }
            }

            return "";
        }

        // 1. candidate extensions
        string fileNameNoExt = Path.GetFileNameWithoutExtension(fileName);
        string ext = Path.GetExtension(fileName);
        string[] candidateExts;
        if (string.IsNullOrEmpty(ext))
        {
            candidateExts = stdExts;
        }
        else
        {
            string[] exts = { ext };
            candidateExts = exts;
        }

        // 2. candidate path:
        //      http://msdn.microsoft.com/en-us/library/windows/desktop/ms682586(v=vs.85).aspx#search_order_for_desktop_applications
        List<string> candidatePaths = new List<string>();

        // application dir
        string fileApp = Process.GetCurrentProcess().MainModule.FileName;
        candidatePaths.Add(Path.GetDirectoryName(fileApp));

        // current dir
        candidatePaths.Add(Directory.GetCurrentDirectory());

        // system dir
        candidatePaths.Add(Environment.SystemDirectory);

        // windows dir
        string winDir = Environment.GetEnvironmentVariable("windir");
        candidatePaths.Add(winDir);

        // PATH
        string[] paths = Environment.GetEnvironmentVariable("PATH").Split(';');
        foreach (string path in paths)
        {
            // strip the trailing '\'
            candidatePaths.Add(Path.GetDirectoryName(path));
        }

        // 3. resolve
        foreach (string eachPath in candidatePaths)
        {
            foreach (string eachExt in candidateExts)
            {
                string fullPath = eachPath + "\\" + fileNameNoExt + eachExt;
                if (File.Exists(fullPath))
                    return fullPath;
            }
        }

        return "";
    }

Answer 1

I don’t know if this can help you:

    public string PathResolver(string filename)
    {
        string[] paths = Environment.GetEnvironmentVariable("PATH").Split(';');
        foreach (string path in paths)
        {
            string fname = Path.Combine(path, filename);
            if (File.Exists(filename)) return fname;
        }
        return "";
    }