How to get the exact path of notepad.exe in order to associate a file extension

Question

I need to associate a file extension I have created “.rulog” with notepad.exe as part of a setup project installation for a windows 7 machine (it’s here since we require admin privileges to write to the registry).

Basically I need to obtain programmatically the exact path of the notepad.exe. Now, I understand that it typically lives in C:\Windows\system32. This is part of PATH system environment variable, so I guess I could loop through all the PATH variables and test if “notepad.exe” exists by combining “notepad.exe” with the current path using File.Exists. However this feels very clumsy.

Essentially I need to add an entry to

Computer\HKEY_CLASSES_ROOT\.rulog\shell\open\command\

with the value of the path of notepad.

Incidentally I can see that .txt in:

Computer\HKEY_CLASSES_ROOT\.txt\ShellNew

has a value for ItemName of

“@%SystemRoot%\system32\notepad.exe,-470”

Perhaps I can just copy this value? Or is this dangerous?(e.g. does not exist).

Out of curiosity, why do some developers insist on creating their own propriety file extensions for something as simple as a text file? — KingCronus, Jan 12 '12 at 17:08
Out of curiosity, if you know that notepad can open your files, why not use an equivalent existing file extension? — murgatroid99, Jan 12 '12 at 17:10
It's very likely an application will be written which will search the directory for these file types. We already have .txt/.log existing for other logging/info hence this is just a provision for it. — Jeb, Jan 12 '12 at 17:16

score 9 · Accepted Answer · answered Jan 12 '12 at 17:08

9

You can use:

Environment.GetEnvironmentVariable("windir") + "\\system32\\notepad.exe";

Or even easier:

Environment.SystemDirectory + "\\notepad.exe";

That way it doesn't matter which drive the os is on.

answered Jan 12 '12 at 17:08

Bali C

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score 3 · Answer 2 · answered Jan 12 '12 at 17:07

3

Copying the value with %systemroot% should be just fine. If it works for the OS, it should work for you!

answered Jan 12 '12 at 17:07

John Gardner

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score 0 · Answer 3 · answered Jan 12 '12 at 18:15

Fool-proof solution:

string NotepadPath = Environment.SystemDirectory + "\\notepad.exe";
if (System.IO.File.Exists(NotepadPath))
{
    Microsoft.Win32.Registry.SetValue("HKEY_CLASSES_ROOT\\.rulog\\shell\\open\\command\\", "", NotepadPath + " %1");
}
else
{
    //do something else or throw new ApplicationException("Notepad not found!");
}

How to get the exact path of notepad.exe in order to associate a file extension

3 Answers3