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Calling a php script from cron


KenHorse
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I have a script that is called from crontab. :

0,5,10,15,20,25,30,35,40,45,50,55 * * * *   /usr/bin/php /var/www/settime.php

I checked back later and notice many instances of php running:

 

root@mypi:~# ps aux |grep settime
root      1646  0.0  0.0   1856   380 ?        Ss   10:20   0:00 /bin/sh -c /usr/bin/php /var/www/settime.php
root      1647  0.0  2.0  75676 19860 ?        S    10:20   0:00 /usr/bin/php /var/www/settime.php
root      1777  0.0  0.0   1856   352 ?        Ss   10:25   0:00 /bin/sh -c /usr/bin/php /var/www/settime.php
root      1778  0.0  2.0  75676 19604 ?        S    10:25   0:00 /usr/bin/php /var/www/settime.php
root      1898  0.0  0.0   1856   340 ?        Ss   10:30   0:00 /bin/sh -c /usr/bin/php /var/www/settime.php
root      1899  0.1  2.0  75676 19672 ?        S    10:30   0:00 /usr/bin/php /var/www/settime.php
root      1943  0.0  0.0   4396   544 pts/0    S+   10:31   0:00 grep settime

settime.php is a script that sets an external clock via /dev/ttyUSB0

 

Obviously I'm doing something wrong as it should run and stop

Edited by KenHorse
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First your crontab is the long way around the barn. Use:

*/5 * * * * /usr/bin/php /var/www/settime.php

Not sure why /bin/sh is involved base on what you've shown. What distro are you running?

Since your didn't show the script how do you expect any help?

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This is running Raspian Buster (Debian 10).

 

Sorry, I didn't think the script itself was an issue but here it is:

<?php
		
include("global.php");
		
		$senddata = "SetClock" . date("His");		
		$serial = serial("$senddata");		
		echo $serial;
		sleep(1);
		$senddata = "SetCalendar" . date("mdy");
		$serial = serial("$senddata");
		echo $serial;
		exit() //<----recently added to try to force close but no difference
?>

In global.php are my serial functions

function serial($cmd){
	$port = "/dev/ttyUSB0";
	$c = exec('stty -F '.$port.' cs8 -parenb -cstopb -echo raw speed 57600');

	if(!file_exists($port)) {
		echo "I am not blocked!";
	} else {
		$f = fopen($port, "w+");
		fwrite($f, $cmd."\r");
		while(1) {
			$dataOut = fgets($f);
			if(strlen($dataOut) > 5) {
			//	echo $dataOut;
				fclose($f);
				break;
			} else {
				fwrite($f, $cmd."\r");
			}	
		}
	}
	return $dataOut;
}

 

Edited by KenHorse
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Your script is probably getting stuck here:

$dataOut = fgets($f);

It's waiting for data from your serial device but the device isn't sending any data so the script just hangs there waiting indefinitely.

You'll have to add some debug logging or something to figure out why or if that's actually the case.  You could also try implementing non-blocking IO and a timeout.

  • Great Answer 1
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I've worked with Raspian quite a bit and using serial devices on it can be tricky. Kicken is exactly right. Also depending on the serial device you are using you may need to install specific drivers. This is especially true if you are using a one-wire device over USB.

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I've had good luck using FTDI based converters with Raspbian.

 

I've done a few searches about actually using stream_set_blocking function but not having any luck. As I've never worked with it before, are there some examples of its implementation (as in actual code examples)?

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Have you tried using a library instead of diy?

I haven't done much work with serial devices and PHP but I do have stuff I could setup and try to generate an example.  If I have time later tonight and you haven't resolved the issue already maybe I will dig it out and give it a try.

 

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This is probably really a raspbian issue so you may want to try the raspberry forum. However, what do you get when you run this script?

for sysdevpath in $(find /sys/bus/usb/devices/usb*/ -name dev); do
    (
        syspath="${sysdevpath%/dev}"
        devname="$(udevadm info -q name -p $syspath)"
        [[ "$devname" == "bus/"* ]] && exit
        eval "$(udevadm info -q property --export -p $syspath)"
        [[ -z "$ID_SERIAL" ]] && exit
        echo "/dev/$devname - $ID_SERIAL"
    )
done

 

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2 hours ago, gw1500se said:

This is probably really a raspbian issue so you may want to try the raspberry forum. However, what do you get when you run this script?

for sysdevpath in $(find /sys/bus/usb/devices/usb*/ -name dev); do
    (
        syspath="${sysdevpath%/dev}"
        devname="$(udevadm info -q name -p $syspath)"
        [[ "$devname" == "bus/"* ]] && exit
        eval "$(udevadm info -q property --export -p $syspath)"
        [[ -z "$ID_SERIAL" ]] && exit
        echo "/dev/$devname - $ID_SERIAL"
    )
done

 

/dev/snd/controlC1 - C-Media_Electronics_Inc._USB_PnP_Sound_Device
/dev/ttyUSB0 - FTDI_FT232R_USB_UART_AH05WJ52

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As I said, this converter works just fine with minicom

 

By the way, what prompted me to use this code for serial comm was that I tried using php_serial.class.php (which now appears to be https://packagist.org/packages/hyperthese/php-serial) but it never seemed to work right. I was unaware of the others listed at packagist so perhaps I should give THEM a try....

Edited by KenHorse
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This code worked for me using a VM with ubuntu on it.  When reading the results after sending the command it will hang for at least as long as the timeout period before returning results since there's no way to determine when the serial device is done sending data otherwise.

<?php

$cmd = implode(' ', array_slice($argv, 1));

$device = serialSetup('/dev/ttyS0', 115200, 8);
var_dump(serial($device, $cmd ?: 'uname -a'));
fclose($device);


function serialSetup($device, $baud, $data){
    $cmd = sprintf('stty -F %s %d cs%d -echo raw', $device, $baud, $data);
    exec($cmd, $output, $ret);
    if ($ret !== 0){
        var_dump($output);
        throw new \RuntimeException('Unable to configure serial device');
    }

    $f = fopen($device, "w+");
    if (!$f){
        throw new \RuntimeException('Unable to open serial device.');
    }

    stream_set_blocking($f, false);
    return $f;
}

function serial($device, $cmd){
    fwrite($device, $cmd . "\n");
    $result = '';
    do {
        try {
            $result .= serialRead($device, 5);
            $timeout = false;
        } catch (RuntimeException $ex){
            $timeout = true;
        }
    } while (!$timeout);

    return $result;
}

function serialRead($device, $timeout = 30){
    $r = [$device];
    $w = $e = [];
    $n = stream_select($r, $w, $e, $timeout, 0);
    if ($n === 1){
        $line = fgets($device) ?: '';
        if ($line !== ''){
            return $line;
        }
    }

    throw new \RuntimeException('Timeout reading from serial device');
}

For the curious, this also sort of works on windows.  The timeout cannot be controlled on windows, so you're stuck with the default (around 120 seconds).  The stty call needs to be replaced with the following call to mode and of course use the appropriate device name (ie, COM1).  The important bit seems to be the to=on parameter in the call to mode, without it windows seems to never timeout on a read and the script would hang indefinitely.

$cmd = sprintf('mode %s BAUD=%d PARITY=n DATA=%d to=on', $device, $baud, $data);

 

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On 10/18/2021 at 2:58 PM, kicken said:

This code worked for me using a VM with ubuntu on it.  When reading the results after sending the command it will hang for at least as long as the timeout period before returning results since there's no way to determine when the serial device is done sending data otherwise.

<?php

$cmd = implode(' ', array_slice($argv, 1));

$device = serialSetup('/dev/ttyS0', 115200, 8);
var_dump(serial($device, $cmd ?: 'uname -a'));
fclose($device);


function serialSetup($device, $baud, $data){
    $cmd = sprintf('stty -F %s %d cs%d -echo raw', $device, $baud, $data);
    exec($cmd, $output, $ret);
    if ($ret !== 0){
        var_dump($output);
        throw new \RuntimeException('Unable to configure serial device');
    }

    $f = fopen($device, "w+");
    if (!$f){
        throw new \RuntimeException('Unable to open serial device.');
    }

    stream_set_blocking($f, false);
    return $f;
}

function serial($device, $cmd){
    fwrite($device, $cmd . "\n");
    $result = '';
    do {
        try {
            $result .= serialRead($device, 5);
            $timeout = false;
        } catch (RuntimeException $ex){
            $timeout = true;
        }
    } while (!$timeout);

    return $result;
}

function serialRead($device, $timeout = 30){
    $r = [$device];
    $w = $e = [];
    $n = stream_select($r, $w, $e, $timeout, 0);
    if ($n === 1){
        $line = fgets($device) ?: '';
        if ($line !== ''){
            return $line;
        }
    }

    throw new \RuntimeException('Timeout reading from serial device');
}

For the curious, this also sort of works on windows.  The timeout cannot be controlled on windows, so you're stuck with the default (around 120 seconds).  The stty call needs to be replaced with the following call to mode and of course use the appropriate device name (ie, COM1).  The important bit seems to be the to=on parameter in the call to mode, without it windows seems to never timeout on a read and the script would hang indefinitely.

$cmd = sprintf('mode %s BAUD=%d PARITY=n DATA=%d to=on', $device, $baud, $data);

 

I changed to /dev/ttyUSB0 and baud rate of 57600 to match my needs. I should receive "+1111" back from the external device. Script is named test

root@mypi:~# php test 11111

string(0) ""
root@mypi:~#

Edited by KenHorse
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I change the fwrite you had to be followed by "\n" instead of "\r", did you try changing that back?  If that doesn't help, you'll have to do some debugging locally and try to figure it out.  Works ok for me with my ardiuno loaded with a quick test program to read the analog pins.

kicken@ubuntu-dev:/Workspace/serial$ php serial_linux.php read_a0
string(32) "readLength=7
cmd=read_a0
793
"

 

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