Our application receives log files via email and so the lines are often broken up by the email client. Once I've read the body of the email in I have a string variable $log in the following format.

Fri Aug 26 11:52:30 2011 OpenVPN 2.1.4 i686-pc-mingw32 [SSL] [LZO2] 
PKCS11] built Fri Aug 26 11:52:30 2011 NOTE: OpenVPN 2.1 requires '--script-security 2' 
or higher to call user-defined scripts or executables Fri Aug 26 11:52:30 开发者_高级运维2011 
Control Channel Authentication: using 'ta.key' as a OpenVPN static key file 
Fri Aug 26 11:52:30 2011 Outgoing Control Channel Authentication: Using 160 
bit message hash 'SHA1' for HMAC authentication Fri Aug 26 11:52:30 
2011 Incoming Control Channel Authentication: Using 160 bit message hash 'SHA1'
for HMAC authentication Fri Aug 26 11:52:30 2011 LZO compression initialized 
Fri Aug 26 11:52:30 2011 Control Channel MTU parms [ L:1558 D:166 EF:66 EB:0 
ET:0 EL:0 ] Fri Aug 26 11:52:30 2011 Socket Buffers: R=[8192->8192] S=[8192->8192]

As shown above the date does not always start on a newline. I'd like to generate an array containing the dates and log messages so that I can output a table with these fields in their own columns. I understand that I would need a regex to match the date field but how do I go about building the array?

I'm just going to update my answer with a new version entirely, since the example log file has changed a lot. Since the log seems to be line broken just about anywhere, this approach - now including a bit of regexp works:

$log="Fri Aug 26 11:52:30 2011 OpenVPN 2.1.4 i686-pc-mingw32 [SSL] [LZO2]  
PKCS11] built Fri Aug 26 11:52:30 2011 NOTE: OpenVPN 2.1 requires '--script-security 2'  
or higher to call user-defined scripts or executables Fri Aug 26 11:52:30 2011  
Control Channel Authentication: using 'ta.key' as a OpenVPN static key file  
Fri Aug 26 11:52:30 2011 Outgoing Control Channel Authentication: Using 160  
bit message hash 'SHA1' for HMAC authentication Fri Aug 26 11:52:30  
2011 Incoming Control Channel Authentication: Using 160 bit message hash 'SHA1' 
for HMAC authentication Fri Aug 26 11:52:30 2011 LZO compression initialized  
Fri Aug 26 11:52:30 2011 Control Channel MTU parms [ L:1558 D:166 EF:66 EB:0  
ET:0 EL:0 ] Fri Aug 26 11:52:30 2011 Socket Buffers: R=[8192->8192] S=[8192->8192] 
";
$str = implode(' ',preg_split("/[ ]*[\r\n]+/", $log));
$arrLogLines=preg_split('/[ ]*([\w]{3} [\w]{3} [0-9]{2} [\d:]+ \d{4}) /',$str,-1,PREG_SPLIT_DELIM_CAPTURE); // Cred to Herbert for the regexp, seems to work fine..
array_shift($arrLogLines);
for ($i=0;$i<sizeof($arrLogLines);$i++) {
    if (($i/2)==(int)($i/2)) {
        $offset=0;
        $strArrIdx='date';
    } else {
        $offset=1;
        $strArrIdx='message';
    }
    $arrLogMessages[($i-$offset)/2][$strArrIdx]=$arrLogLines[$i];
}
var_dump($arrLogMessages);

It produces the expected:

array(8) {
  [0]=>
  array(2) {
    ["date"]=>
    string(24) "Fri Aug 26 11:52:30 2011"
    ["message"]=>
    string(56) "OpenVPN 2.1.4 i686-pc-mingw32 [SSL] [LZO2] PKCS11] built"
  }
  [1]=>
  array(2) {
    ["date"]=>
    string(24) "Fri Aug 26 11:52:30 2011"
    ["message"]=>
    string(102) "NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables"
  }
  [2]=>
  array(2) {
    ["date"]=>
    string(24) "Fri Aug 26 11:52:30 2011"
    ["message"]=>
    string(75) "Control Channel Authentication: using 'ta.key' as a OpenVPN static key file"
  }
  [3]=>
  array(2) {
    ["date"]=>
    string(24) "Fri Aug 26 11:52:30 2011"
    ["message"]=>
    string(98) "Outgoing Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication"
  }
  [4]=>
  array(2) {
    ["date"]=>
    string(24) "Fri Aug 26 11:52:30 2011"
    ["message"]=>
    string(98) "Incoming Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication"
  }
  [5]=>
  array(2) {
    ["date"]=>
    string(24) "Fri Aug 26 11:52:30 2011"
    ["message"]=>
    string(27) "LZO compression initialized"
  }
  [6]=>
  array(2) {
    ["date"]=>
    string(24) "Fri Aug 26 11:52:30 2011"
    ["message"]=>
    string(63) "Control Channel MTU parms [ L:1558 D:166 EF:66 EB:0 ET:0 EL:0 ]"
  }
  [7]=>
  array(2) {
    ["date"]=>
    string(24) "Fri Aug 26 11:52:30 2011"
    ["message"]=>
    string(46) "Socket Buffers: R=[8192->8192] S=[8192->8192] "
  }
}

I'm not a regex pro and sure there is an easier way, but this works:

$input = "Wed Aug 03 13:56:31 2011 OpenVPN 2.1.4 i686-pc-mingw32 [SSL] [LZO2]
[PKCS11] built on Mar 12 2011
Wed Aug 03 13:56:31 2011 NOTE: OpenVPN 2.1 requires '--script-security
2' or higher to call user-defined scripts or executables
Wed Aug 03 13:56:31 2011 Control Channel Authentication: using 'ta.key'
as a OpenVPN static key file";

preg_match_all('/([\w]{3} [\w]{3} [0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2} [0-9]{4}) (.*)/', $input, $matches, PREG_SET_ORDER);

var_dump($matches);

This results in:

array(3) {
    [0] =>
    array(3) {
        [0] =>
        string(67) "Wed Aug 03 13:56:31 2011 OpenVPN 2.1.4 i686-pc-mingw32 [SSL] [LZO2]"
        [1] =>
        string(24) "Wed Aug 03 13:56:31 2011"
        [2] =>
        string(42) "OpenVPN 2.1.4 i686-pc-mingw32 [SSL] [LZO2]"
    }
    [1] =>
    array(3) {
        [0] =>
        string(70) "Wed Aug 03 13:56:31 2011 NOTE: OpenVPN 2.1 requires '--script-security"
        [1] =>
        string(24) "Wed Aug 03 13:56:31 2011"
        [2] =>
        string(45) "NOTE: OpenVPN 2.1 requires '--script-security"
    }
    [2] =>
    array(3) {
        [0] =>
        string(71) "Wed Aug 03 13:56:31 2011 Control Channel Authentication: using 'ta.key'"
        [1] =>
        string(24) "Wed Aug 03 13:56:31 2011"
        [2] =>
        string(46) "Control Channel Authentication: using 'ta.key'"
    }
}

I believe this is what you're looking for:

<?php

$log = <<<LOG
Wed Aug 03 13:56:31 2011 OpenVPN 2.1.4 i686-pc-mingw32 [SSL] [LZO2] 
[PKCS11] built on Mar 12 2011
Wed Aug 03 13:56:31 2011 NOTE: OpenVPN 2.1 requires '--script-security 
2' or higher to call user-defined scripts or executables
Wed Aug 03 13:56:31 2011 Control Channel Authentication: using 'ta.key' 
as a OpenVPN static key file
LOG;


function splitLog($log)
{
    $log = str_replace("\n",'~',$log);
    $log = str_replace("\r",'',$log);
    $log .= '~';
    preg_match_all('/([\w]{3} [\w]{3} [0-9]{2} [\d:]+ \d{4})((?:.*?~){2})/', $log, $m);

    $logArray = array();

    foreach($m[0] as $k=>$v)
    {
        $a['date'] = $m[1][$k];
        $a['message'] = trim(str_replace('~', '', $m[2][$k]));
        array_push($logArray, $a);
    }

    return $logArray;
}

$logArray = splitLog($log);
var_dump($logArray);

?>

Output

array
  0 => 
    array
      'date' => string 'Wed Aug 03 13:56:31 2011' (length=24)
      'message' => string 'OpenVPN 2.1.4 i686-pc-mingw32 [SSL] [LZO2] [PKCS11] built on Mar 12 2011' (length=72)
  1 => 
    array
      'date' => string 'Wed Aug 03 13:56:31 2011' (length=24)
      'message' => string 'NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables' (length=102)
  2 => 
    array
      'date' => string 'Wed Aug 03 13:56:31 2011' (length=24)
      'message' => string 'Control Channel Authentication: using 'ta.key' as a OpenVPN static key file' (length=75)

If every line starts with a date like this, you can just use substr. The date exists on every line and always with the same length. Alright, the first line ends with a sate too, but that has a different meaning and a different notation. Regex isn't gonna help you with that either.