Have you tried checking if you have xdotool installed? Also try to reproduce this in another C# project, only trying to run xdotool. Check if you have imported System.Diagnostics .

Try using the Process class instead (I wouldn't recommend this one for your use case as it works better on windows, but it might work):

Process xdotool = new Process();

xdotool.StartInfo.FileName = "xdotool";
xdotool.StartInfo.Arguments = "key comma";
xdotool.Start();
xdotool.WaitForExit(); // wait for finish