Add W3docsLogviewerBundle in your composer.json:

{
    "require": {
        "w3docs/log-viewer-bundle": "dev-master"
    }
}

Now update composer.

Composer will install the bundle to your project's vendor/w3docs directory.

Enable the bundle in the kernel:

<?php
// app/AppKernel.php

public function registerBundles()
{
    $bundles = array(
        // ...
        new W3docs\LogViewerBundle\W3docsLogViewerBundle()
    );
}

show logs from prod.log level error or higher (CRITICAL, ALERT, EMERGENCY)

app/console log:view prod.log --level=error

show logs for given chanal "security"

app/console log:view prod.log --logger=security

group errors and order then, this will allow to find most occurred logs

app/console log:view prod.log --group

group and limit result to 10 (log must be at least 10 times or any other given number).

app/console log:view prod.log --group --having=10

filtering by start and/or end date

app/console log:view prod.log --start=01-03-2015 --end=05-03-2015