How can I launch some command (console application) in iTerm2 on system boot? There should be only one instance of this application.
Create a script which will run Your app. Something like:
Save it, change this to be executable with
chmod +x in Terminal or iTerm2 app. Right click on this file and choose Get Info, select the prefered app which will open it (in Your case iTerm2 app). Open Preferences.app, go to Users and Groups -> Login and add Your script there. With this once You login Your script will be opened in iTerm2 app.