Yes you can do this.
- You can distribute/provide GPL and non-GPL software side by side, without any further license obligations. This is often called “mere aggregation”.
- A non-GPL program can launch a GPL program without any further license obligations, provided that they are clearly separate programs.
For example, you could create a proprietary text editor that internally uses the Markdown text format. You could bundle a copy of the GPL-licensed Pandoc tool to export the Markdown as various formats, provided that you do this by launching Pandoc as a separate process (in contrast to embedding Pandoc as a library in your application).
Of course, you must still comply with the GPL for the GPL-covered program. In particular, this means:
- providing a copy of the license
- when providing binaries: providing the complete corresponding source code (see the license text for details)
If you have an installer that bundles your own software with GPL-covered software, it should be possible to install the GPL software separately, without having to agree to any of your EULAs or licenses (you must not restrict the recipient's rights under the GPL). Your software should also work with modified variants of the GPL-covered program, so e.g. don't calculate checksums for the GPL-covered binaries.
Process.Start("GPLProcess.exe");
and pass some parameters