loghighlight.php

<?php

if ($argc !== 2) {
    die('File to highlight was expected as first argument.');
}

$replace = [
    // base styles
    'EMER' => ["\e[45;30m", " \e[0m "],
    'ALRT' => ["\e[43;30m", " \e[0m "],
    'CRIT' => ["\e[41;30m", " \e[0m "],
    'ERRR' => ["\e[40;31m", " \e[0m "],
    'WARN' => ["\e[40;33m", " \e[0m "],
    'NOTE' => ["\e[40;36m", " \e[0m "],
    'INFO' => ["\e[40;34m", " \e[0m "],
    'DBUG' => ["\e[40;37m", " \e[0m "],
    // aliases
    'EMERGENCY' => 'EMER',
    'ALERT' => 'ALRT',
    'CRITICAL' => 'CRIT',
    'ERROR' => 'ERRR',
    'WARNING' => 'WARN',
    'NOTICE' => 'NOTE',
    'INFORMATION' => 'INFO',
    'DEBUG' => 'DBUG',
];

echo preg_replace_callback(
    sprintf(
        '/^(.*?)\\s(%s)\\s-\\s/m',
        implode('|', array_keys($replace))
    ),
    function ($matches) use ($replace) {
        $style = $replace[$matches[2]];

        if(is_string($style)){
            $style = $replace[$style];
        }

        return sprintf(
            '%s%s %s%s ',
            $style[0],
            $matches[1],
            $matches[2],
            $style[1]
        );
    },
    file_get_contents($argv[1])
);