From: josef@invalid.invalid   
      
   Hi,   
      
   I used to use the sysfs interface to the GPIO pins (/sys/class/gpio) but   
   I understand that is deprecated nowadays. So I tried to switch to lgpio   
   which looks OK. However, I have problems writing and reading back pin   
   states from different programs.   
      
   My setup is as follows:   
   I have a couple of relays (solid state and mechanical ones) that control   
   various external devices.   
   I use one program to switch devices on and off and want to use another   
   program to read back the state of the device.   
      
   Doing that with sysfs is easy:   
   1) export the pin:   
          echo $pin > /sys/class/gpio/export   
          echo $direction > /sys/class/gpio/gpio$pin/direction   
       this needs to be done only once.   
   2) write the state of the pin, thus switching the device on/off:   
          echo $newstate > /sys/class/gpio/gpio$pin/value   
       this is done every time this is required   
   3) read back the state of the pin   
          value=$(