How to launch emulation station in Python script?

[gryffin13]

What is the correct way to launch emulation station from a Python script? If I'm at the terminal I can just type "emulationstation" and hit enter. But I don't know the correct syntax to launch from a script. I've tried variations of os.system("emulationstation") but it doesn't work correctly. There has to be a way, but I am a beginner and cannot find any answers despite lots of searching. Anyone know the answer?

[geneworld]

import subprocess

subprocess.call("emulationstation", shell=True)

[gryffin13]

When I do that I get an error:
"emulationstation should not be run as root. If you used 'sudo emulationstation' please run without sudo"

As far as I know, I am not using 'sudo emulationstation'.

Below is the code in case you'd like to see. I am triggering the code to run at boot with this line in the rc.local file:
python /home/pi/randomSimpsons.py &

#!/usr/bin/env python2.7
# main script by Alex Eames http://RasPi.tv
# http://RasPi.tv/how-to-use-interrupts-with-python-on-the-raspberry-pi-and-rpi-gpio-part-3
import RPi.GPIO as GPIO
import time
import os
import random
import subprocess
directory = "/home/pi/simpsons/"
redirectory = "/home/pi/"

GPIO.setmode(GPIO.BCM)

# GPIO 27 & 17 set up as inputs, pulled up to avoid false detection.
# Both ports are wired to connect to GND on button press.
# So we'll be setting up falling edge detection for both
GPIO.setup(27, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(17, GPIO.IN, pull_up_down=GPIO.PUD_UP)

# GPIO 3 set up as an input, pulled UP
GPIO.setup(3, GPIO.IN, pull_up_down=GPIO.PUD_UP)


#this callback closes emulationstation and runs a random video from the directory specified
#structure of random episode code is taken from Stephen Coyle's project here: http://stephencoyle.net/software/randomSimpsons.py
def my_callback(channel):
    episode = random.choice(os.listdir(directory))
    cmd = "nohup omxplayer -b -o hdmi " + "'" + directory + episode + "' &"
    os.system("killall emulationstation")
    os.system('killall omxplayer.bin')
    os.system(cmd)

#this callback closes omxplayer and restarts emulationstation
def my_callback2(channel):
    print("test1")
    os.system('killall omxplayer.bin')
    print("test2")
    cmd2 = "nohup emulationstation " + "'" + redirectory + "' &"
    
   # os.system("emulationstation")
   # os.system(cmd2)    
    subprocess.call("emulationstation", shell=True)
    print("test3")



GPIO.add_event_detect(17, GPIO.FALLING, callback=my_callback, bouncetime=300)

GPIO.add_event_detect(27, GPIO.FALLING, callback=my_callback2, bouncetime=300)

try:
    GPIO.wait_for_edge(3, GPIO.FALLING)
    print("self destruct initiated")
    os.system("sudo shutdown -h now")
    #os.system('sudo python /home/pi/randomSimpsons.py')  # point this to the location of this file

except KeyboardInterrupt:
    GPIO.cleanup()  # clean up GPIO on CTRL+C exit
GPIO.cleanup()  # clean up GPIO on normal exit

[geneworld]

@gryffin13 said in How to launch emulation station in Python script?:

cmd2 = "nohup emulationstation " + "'" + redirectory + "' &"

What's this line for?

[gryffin13]

@geneworld
That was a variable in one of my previous methods I tried. The line that called it (os.system(cmd2)) is commented out below.

[BuZz]

/etc/rc.local is executed as root.

You can't launch ES for retropie that way - as it needs to be attached to a TTY. You could try launching your script from the /opt/retropie/configs/all/autostart.sh though.

[gryffin13]

@buzz
Ok I'm a Linux beginner and I guess I didn't understand that it was executed as root. I'll try your suggestion and see if that works for me. Thanks.

Also for my own education - what does "attached to a TTY" mean?

[BuZz]

@gryffin13 attached to a terminal rather than in the background - as runcommand needs to capture input and output to the terminal etc.

[gryffin13]

@buzz
Sorry for the long delay - I was prevented from working on this. When I did get around to it though, I was able to use this advice to come up with a solution. Thanks a bunch!