tail by php

gistfile1.aw

function tail_read($filename, $lines = 10, $offset = 4096, $onLine = null) {    
    if(is_callable($lines)) {        
        $onLine = $lines;
        $lines = 10;        
        $offset = 4096;
    }    
    if(is_callable($offset)) {        
        $onLine = $offset;        
        $offset = 4096;    
    }    
    $line = $tmp = $remainder = $read = '';
    $seek_offset = -$offset;    
    $fp = fopen($filename, 'r');    
    while($lines > 0 && fseek($fp, $seek_offset, SEEK_END) === 0) {        
        $tmp = rtrim(fread($fp, $offset), "\n") . $remainder;
        while($lines > 0 && ($pos = strrpos($tmp, "\n")) !== FALSE) {            
            $line = substr($tmp, $pos + 1);
            $flag = is_callable($onLine) ? call_user_func_array($onLine, array($line, &$lines)) : true;
            if($flag) {
                $read = $line . "\n" . $read;
                $lines--;
            }
            $tmp = substr($tmp, 0, $pos);
        }
        $remainder = $tmp;
        $seek_offset = $seek_offset - $offset;
    }
    fclose($fp);
    return $read;
}