I want to open a file's location and select the file in explorer on Mac, Ubuntu from MonoDevelop.
This code is working on Windows (but it is not working on Mac and Ubuntu):
System.Diagnostics.Process.Start("explorer.exe", "/select, " + fileaddress);
Using Process.Start()
you bypass the .NET framework and move into the platform you're running onto, executing an arbitrary process.
On Windows you want to open the Windows Explorer, on Mac you want to open Finder and on Ubuntu it's simply called File Browser.
There is no Environment.OpenFileBrowser(string path)
method in the framework, so you will have to let your program determine which platform it is running on, and open the approperiate file viewer.
See How to check the OS version at runtime e.g. windows or linux without using a conditional compilation statement to perform the former.