Trying to learn the webiopi and python. I have a simple button to turn off and on a relay. Here is the HTML

    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>WebIOPi | Example App</title>
        <script type="text/javascript" src="/webiopi.js"></script>
        <script type="text/javascript">
        webiopi().ready(function() {

                // Create a "Light" labeled button for GPIO 17
                var light_button = webiopi().createGPIOButton(17, "Light", function() {
                    // Call the logtofile macro 
                    webiopi().callMacro("logtofile", [], '');

                // Append buttons to HTML element with ID="controls" using jQuery

                // Refresh GPIO buttons
                // pass true to refresh repeatedly of false to refresh once

        <style type="text/css">
                button {
                        display: block;
                        margin: 5px 5px 5px 5px;
                        width: 160px;
                        height: 45px;
                        font-size: 24pt;
                        font-weight: bold;
                        color: white;

                #gpio17.LOW {
                        background-color: Black;

                #gpio17.HIGH {
                        background-color: Blue;
        <div id="controls" align="center"></div>

Straight forward stuff you will find in the tutorials around the web. I added this

// Call the logtofile macro 
webiopi().callMacro("logtofile", [], '');

To call a macro. My script file looks like this

import webiopi

GPIO = webiopi.GPIO

BLUE = 17 # GPIO pin using BCM numbering(BOARD 11)
RED = 18 # GPIO pin using BCM numbering(BOARD 12)
GREEN = 27 # GPIO pin using BCM numbering(BOARD 13)

# setup function is automatically called at WebIOPi startup
def setup():
    # set the GPIO used by the light to output
    GPIO.setFunction(BLUE, GPIO.OUT)
    GPIO.setFunction(RED, GPIO.OUT)
    GPIO.setFunction(GREEN, GPIO.OUT)

# loop function is repeatedly called by WebIOPi 
def loop():
    # gives CPU some time before looping again

# destroy function is called at WebIOPi shutdown
def destroy():
    GPIO.digitalWrite(BLUE, GPIO.LOW)

def logtofile():
    call([" sudo python /home/pi/buttonlog.py "], shell=False)

My logtofile macro is just calling the /home/pi/buttonlog.py that looks like this.

import datetime
i = datetime.datetime.now()

f.write(i.isoformat() + '\n')

Straight forward code that writes the date to the /home/pi/buttonlog.txt However when I click the button I do not get the script to add the date to the file. If I run the buttonlog.py all by itself it writes to the file as expected. Am I missing something? I know this is probably not the simplest way to accomplish this but I am trying to understand how it works.

1 Answer 1


I think you're missing the f.close() command that actually syncs the change to the file system.

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