Possibly Improved Method for Kodi / ES Switching?

xrayspx

I've recently begun using RetroPie on a TV to run both Kodi and EmulationStation, after many years using it in an arcade cabinet.

I'm not a programmer, and see I'm immediately breaking style guidelines, but I just wanted to toss this out to see if anyone might want to implement it in a more permanent way. The current recommended method for booting to Kodi and Switching to EmulationStation seems to work well, though only once, and in only one direction. If you quit ES, you exit to a shell and if you navigate to Ports -> Kodi, now you're running both ES and Kodi, and quitting Kodi takes you back to the Ports menu.

I considered populating /opt/retropie/configs/all/autostart.sh with:

kodi-standalone
emulationstation
kodi-standalone
emulationstation
etc.

Rather than do that though, I wrote a small script and am calling that from autostart.sh. :

#! /bin/bash

while getopts f: name
do
  case $name in
    f) fval="$OPTARG";;
    ?) printf "Usage %s: [-f application to start] args\n" $0
    exit 2;;
  esac
done

while :
do
  if [ $fval = kodi ]
  then
    kodi-standalone
    fval="emulationstation"
  elif [ $fval = emulationstation ]
  then
     emulationstation
    fval="kodi"
  fi
done

I'll likely add some process control to make sure I don't wind up running multiple instances, and an option to switch to a full desktop, but this seems to work well for quitting Kodi to get to ES and then quitting ES to get back to Kodi. Restarting ES to pick up new ROMs works as expected (Doesn't re-launch into Kodi).

There's the drawback of making it somewhat difficult to get a shell on the console, but in years of using a Raspberry Pi on my TV, I can't think of the last time I needed to.

mitu

Wouldn't have been easier to put the same infinite loop in autostart.sh ?

while :
do
 kodi-standalone
 emulationstation
done

xrayspx

@mitu Actually yeah, probably, thanks! And if I'd thought of it I think I'd have been happy enough :-) Now your comment will show up in search results and may save the next person some time.

The main reason I didn't even consider editing autostart.sh directly was because it could potentially be overwritten by RetroPie-setup and I'd have to go back and restore my changes. I tend to go off on a tangent, build a thing, and plug it in in the least-invasive way possible.

But I've actually just taken a few minutes added the ability to hijack that loop so I can insert one-off commands through Kodi main-menu items, like quit kodi gracefully and run startx, then return to Kodi smoothly when I quit the desktop session. So for my part, I'm in good shape for Maximum Convenience.

Rascas

I am sorry but I don't see this as a kind of improvment, by the contrary. The way ES was written, when you launch some program from it, it enters a kind of hibernation mode, it stays in RAM but it consumes virtually 0% CPU resources. This applies to Kodi or any game you launch from it. So tying to do something like this you will get pretty much 0 performance improvement. Not to mention that doing a loop like that, if one program crashes, it may render the system trying to load two instances of one program which may cause a lot of problems if not getting a completelly useless system that you will have to restart via ssh or unplugging the power cord.

Has you may know, you can always check the current CPU, Memory and stuff by running top (and other programs) remotely via ssh. The memory usage of ES depends greatly on the number of systems, games, covers, etc you have on it.
But one RPi 2 and above, with 1GB of RAM, is almost sure enough for you to don't get out of RAM.

Rascas

Not to mention that, if you have a lot of systems, games, covers, etc, ES can take some time to start, and doing that will take longer to switch from programs.

huey

This doesn't not satisfy your requirement exactly, but I found it to be pretty useful for a more general solution. Note that this works in more cases than just upon startup as CTRL + D will always launch this script in shell. In my case, CTRL + D then K will bring up Kodi, and the rest is up to the user to define.

# /opt/retropie/configs/all/autostart.sh

# press ctrl + d will automatically launch this script in terminal
# making it a useful hub for executing more "wordy" commands

# note that actually, any key other than the pre-defined ones will abort
echo "==================================================================="
echo "=== EmulationStation starting in 3 seconds. Press "z" to abort. ==="
echo "==================================================================="

# read 1 character from input with a 3-second timeout 
# and save in variable $input
read -n 1 -t 3 input
echo ""

# default case
# if the input is empty or time runs out, start emulation station
# works without keyboard, e.g., when only controller is connected
# in case keyboard is indeed connected, hit enter or space to skip the wait
if [ -z "$input" ]
then
    emumlationstation

# if "x", then start desktop
elif [ "$input" == "x" ]
then
    startx

# the rest is for illustrative purposes
# if "s", then shutdown
elif [ "$input" == "s" ]
then
    sudo shutdown now

# if "r", then reboot
elif [ "$input" == "r" ]
then
    sudo reboot

# if "k", then start kodi
elif [ "$input" == "k" ]
then
    kodi

# if anything else, print help info
else
    # print help info
fi

xrayspx

@Rascas

Yeah this is really in the case where ES is a secondary use of the machine and it's primarily a Kodi box. The default for "start Kodi first" is as listed above, an autostart.sh which runs Kodi, then when Kodi is quit, runs ES.

If just having that loop in Mitu's answer had been the default behavior for the "Start Kodi First" option in retropie-setup, that would have worked fine for me and I'd have had no complaints. That's exactly how I expected it to work. However, since I'd already written my script, I did add in the option of injecting commands into the loop. So I have a home-screen icon in Kodi to exit to a Desktop. It adds that command to the loop then does a graceful exit of Kodi.

I agree that in the case where ES is the primary use of the Pi, as on my arcade cabinet, it's best to just launch Kodi from within ES for the rare times I want to use it.

I do think that Mitu's answer might be a sensible default in this use case:

while :
do
kodi-standalone
emulationstation
done

Thanks again

pepie34

Isn't it cleaner to use systemd / services in order to do so ?

It is explained here how to cycle between 2 services:
https://forum.kodi.tv/showthread.php?tid=288584

For kodi.service (configured as a user service not system wide service contrary to the above link) :

[unit]
...
Conflicts = emulstation.service
...

[service]
...
ExecStopPost = /usr/bin/systemctl --user start emulstation.service
...

And for emulstation.service

[unit]
...
Conflicts = kodi.service
...

[service]
...
ExecStopPost = /usr/bin/systemctl --user start kodi.service
...

Emulstation and kodi should not be services enabled/start by default at boot but rather
autostart.sh start the first service by something like:

systmctl --user start kodi.service

if kodi is configured to be the first one.

To go further we can also think about replacing the autostart script by a retropie service which is enabled at boot time. At start, it launches the first configured service. At stop it ensures that emulstation and kodi are stoped.

If the service is run as pi user (which is more secure), the pi user must be lingered to enable autostart of the service at boot even if the user is not logged in.

loginctl enable-linger pi
systemctl --user enable retropie

Advantages:

All the services could be controlled, inspected, logged through the systemd tools
Not need for automatic login
It could be easily extended to any number of services not just 2.