need to read data from a log... tail, grep and inotifywait

Question

I have data on one server that comes into a continuously growing log file. I need to tail that log and grep some information and then send that to another server for php to insert into a database. The computer that has the log can't be allowed access to the database. I tried this so far but my syntax on the bash command is wrong and I can't figure out if this is the way to do it or if there would be a better way? Netcat was another thought...

monitor.sh

#!/bin/sh

tail -f /usr/local/log/thelog.log | grep -B1 "ABC=" > /usr/local/log/output.log;  

while inotifywait -e modify /usr/local/log/output.log; do
sleep 10;  
php /usr/bin/send.php;  
done

send.php

<?php
//extract data from the post
//extract($_POST);
//set POST variables

$data = 'tail -n 3 /usr/local/log/output.log';
$url = 'http://www.blahblah.com/logtodb.php';

$data = str_replace("A", "", $data);
$data = str_replace("B=", "", $data);
$data = str_replace("C=", "", $data);
$data = str_replace("D=", "", $data);

$fields = array(
'data'=>urlencode($data)d,
);

//url-ify the data for the POST
foreach($fields as $key=>$value) { $fields_string .= $key.'='.$value.'&'; }
rtrim($fields_string,'&');

//open connection
$ch = curl_init();

//set the url, number of POST vars, POST data
curl_setopt($ch,CURLOPT_URL,$url);
curl_setopt($ch,CURLOPT_POST,count($fields));
curl_setopt($ch,CURLOPT_POSTFIELDS,$fields_string);

   //execute post
   $result = curl_exec($ch);

   //close connection
   curl_close($ch);
   A>

logtodb.php reads the post

Answer 1

To execute an external command in PHP you need to use back ticks not single quotes. They are usually found below the ESC key on the keyboard.

$data = 'tail -n 3 /usr/local/log/output.log';

should be

$data = `tail -n 3 /usr/local/log/output.log`;

Also you should not be using tail -f as it does not return until you provide an EOF(control+D).

Answer 2

I've never done it, but it ought to (probably) work:

Why not just use a domain socket (FIFO)?

$ mkfifo /path/to/my/fifo
$ tail -f /path/to/log > /path/to/my/fifo &
$ php send.php < /path/to/my/fifo

send.php should be able to just loop on $line=fread(...) from now until enternity....

Answer 3

You can try this:

#!/bin/sh
tail -f /usr/local/log/thelog.log | grep -B1 "ABC=" | while read line
do
    php /usr/bin/send.php $line
done

Note: you will have to change send.php to accept the data as an argument (instead of reading it from the output log).