First, it is important understand what happens when you execute dnx. Currently, the command for dnx on Linux and OS X is just a shortcut to this script file. If you inspect this 16-line file, you will see that, in most cases, dnx is just an abbreviation for mono $MONO_OPTIONS "$DIR/dnx.mono.managed.dll" "[email protected]"

Understanding this enables you to change how DNX runs mono in the following ways.

Use the MONO_OPTIONS variable to pass runtime flags to mono

This is useful if you need to alter the way DNX bootstraps mono. Here are some useful examples.

Find out which version of Mono DNX is using

Execute MONO_OPTIONS=--version dnx

Debug and get a more detailed stack trace

Execute MONO_OPTIONS=--debug dnx . run

Change the mono runtime

If you have multiple versions of mono installed, it may be useful to change which version mono is using. DNX will first look within the runtime folder for an executable mono. If not, it will use the system default. You can override the system default mono by adding a symbolic link into the runtime folder.

For example, I have a custom build of mono in my home directory, but also have a system installation of Mono (so I can use Xamarin Studio).

To override, follow these steps.

  1. Naviate to the folder containing DNX. dirname `which dnx`
  2. Add a symbolic link. For example, ln -s /Users/nmcmaster/dev/mono-src/bin/mono ./

Now DNX will use /Users/nmcmaster/dev/mono-src/bin/mono instead of /usr/bin/mono