Make cURL output STDERR to file (or string)

Question

We\'re trying to debug some cURL errors on the server, and I would like to see the STDERR log. Currently, all we can see for our error is \"error code: 7\" and that we can\'

Answer 1

You are making couple mistakes in your example:

1) you have to call curl_exec() prior to reading from the "verbose log", because curl_setopt() doesn't perform any action, so nothing can be logged prior to the curl_exec().

2) you are opening $curl_log = fopen("curl.txt", 'w'); only for write, so nothing could be read, even after you write to the file and rewind the internal file pointer.

So the correct shortened code should look like:

<?php
$curl = curl_init();
$curl_log = fopen("curl.txt", 'rw'); // open file for READ and write
$url = "http://www.google.com";

curl_setopt_array($curl, array(
    CURLOPT_URL             => $url,
    CURLOPT_VERBOSE         => 1,
    CURLOPT_STDERR          => $curl_log,
    CURLOPT_RETURNTRANSFER  => 1
));

$response = curl_exec($curl);

rewind($curl_log);
$output= fread($curl_log, 2048);
echo "<pre>". print_r($output, 1). "</pre>";
fclose($curl_log);

// ...

?>

NOTE: verbose log could be longer than 2048 bytes, so you could "fclose" the $curl_log after curl_exec() and then read the whole file with for example file_get_contents(). In that case, the point 2) should not be considered as mistake :-)

Answer 2

From php manual for function curl_setopt:

CURLOPT_FILE The file that the transfer should be written to. The default is STDOUT (the browser window).  

Answer 3

I needed to close the file before being able to read it, this worked for me:

$filename = 'curl.txt';
$curl_log = fopen($filename, 'w'); // open file for write (rw, a, etc didn't help)
curl_setopt($ch, CURLOPT_VERBOSE, 1);
curl_setopt($ch, CURLOPT_STDERR, $curl_log);        

$result = curl_exec($ch);

fclose($curl_log);      
$curl_log = fopen($filename, 'r'); // open file for read
$output= fread($curl_log, filesize($filename));
echo $output;

(PHP 5.6.0, Apache/2.2.15)

Answer 4

A bit late to the party, but this page still pops up high in Google, so let's go.

It seems that CURLOPT_VERBOSE doesn't log anything if CURLINFO_HEADER_OUT is also set to TRUE.

This is a know bug in PHP (#65348), and due to reasons they decided not to fix it.

Answer 5

Putting al above answers together, I use this function to make a Curl Post Request with loggin to a file option:

function CURLPostRequest($url, array $post = NULL, array $options = array(), $log_file = NULL){
    $defaults = array(
            CURLOPT_POST => 1,
            CURLOPT_HEADER => 0,
            CURLOPT_URL => $url,
            CURLOPT_FRESH_CONNECT => 1,
            CURLOPT_RETURNTRANSFER => 1,
            CURLOPT_FORBID_REUSE => 1,
            CURLOPT_TIMEOUT => 4,
            CURLOPT_POSTFIELDS => http_build_query($post)
    );

    if (is_resource($log_file)){
        $defaults[CURLOPT_VERBOSE]=1;
        $defaults[CURLOPT_STDERR]=$log_file;
        $defaults[CURLINFO_HEADER_OUT]=1;
    }

    $ch = curl_init();
    curl_setopt_array($ch, ($options + $defaults));
    if( ! $result = curl_exec($ch)){
        throw new Exception(curl_error($ch));
    }

    if (is_resource($log_file)){

        $info = curl_getinfo($ch);

        if (isset($info['request_header'])){
            fwrite($log_file, PHP_EOL.PHP_EOL.'* POST Content'.PHP_EOL.PHP_EOL);
            fwrite($log_file, print_r($info['request_header'],true));
            fwrite($log_file, http_build_query($post));
        }

        fwrite($log_file, PHP_EOL.PHP_EOL.'* Response Content'.PHP_EOL.PHP_EOL);
        fwrite($log_file, $result.PHP_EOL.PHP_EOL);
    }

    curl_close($ch);
    return $result;
}

Hope this help to someone.

Answer 6

You should put

$output = fread($curl_log, 2048);
echo $output; // This returns nothing!
fclose($curl_log);

after $response = curl_exec($curl); otherwise, file is closed during curl is executing.