gistfile1.py

#!/usr/bin/python

import time
import RPi.GPIO as GPIO
import spidev
import psutil

SEG = [
    0b00111111 # 0
,   0b00000110 # 1
,   0b01011011 # 2
,   0b01001111 # 3
,   0b01100110 # 4
,   0b01101101 # 5
,   0b01111101 # 6
,   0b00100111 # 7
,   0b01111111 # 8
,   0b01101111 # 9
] 

spi = spidev.SpiDev()
spi.open(0, 0)
spi.max_speed_hz = 10000

try:
    while True:
        users = len(psutil.users())
        spi.xfer([SEG[users]])
        time.sleep(0.4)
except:
    spi.close()
    GPIO.cleanup()