fileobject.php

<?php
$docs = new FilesystemIterator('common/documents', FilesystemIterator::UNIX_PATHS);
foreach ($docs as $doc) {
    if ($doc->getExtension() == 'txt') {
        //echo $doc . '<br>';
        $textfile=$doc->openFile('r+');
        $textfile->setFlags(SplFileObject::SKIP_EMPTY | SplFileObject::READ_AHEAD | SplFileObject::DROP_NEW_LINE);
        echo '<h2>'.$textfile->getFilename().'</h2>';
        foreach ($textfile as $line) {
        	echo "$line<br>";
        }
        $textfile->seek(2);
        echo '<br>';
        echo 'This is the fourth line'.$textfile->current();
        while (!$textfile->eof()) {
			$textfile->next();            
        }

        // this line is add to all txt file
        $textfile->fwrite("\r\n\r\n This line is added dynamically.");
    }
}