diff --git a/tools/README.md b/tools/README.md
index 1cf543c..d298f35 100644
--- a/tools/README.md
+++ b/tools/README.md
@@ -1,69 +1,69 @@
 # boz-mw command line tools
 
 This is a directory for command line tools that uses the boz-mw framework. Actually there are not too much tools.
 
 ## Configuration 
 
 Copy the `config-example.php` to `config.php` and fill it with your bot credentials.
 
 ## Available scripts
 
 ### Replace script - `replace.php`
 
 This is a script to sobstitute text in the wikitext from an API query.
 
 e.g. to transform in *farfallese* the whole Italian Wikipedia:
 
 ```bash
 ./replace.php --wiki=itwiki --generator=allpages \
     a afa \
     e efe \
     i ifi \
     o ofo \
     u ufu
 ```
 
 e.g. to replace a simple template parameter in top of the page, e.g. from `{{Sito web|commerciale = Sì}}` to `{{Sito web|lucro = Sì}}`:
 
 ```bash
 ./replace.php \
     --wiki=itwiki \
     --generator=transcludedin \
     --titles=Template:Sito_web \
     --rvsection=0 \
     --regex \
     '/\|commerciale(.*=.*)(Sì|No|sì|no)(.*)/' \
     '|lucro$1$2$3'
 ```
 
 Other options:
 
 ```bash
 ./replace.php --help
 ```
 
 You can see some [examples](./examples).
 
 ### Mega export - `mega-export.php`
 
 This is a script that acts similar to the `[[Special:Export]]` page, but exporting the full page history.
 
 Note that you have to provide your user credentials in the `config.php` script in order to download more than `50` revisions at time.
 
 ```
 Usage:
- ./mega-export.php --wiki=WIKI [OPTIONS] Page_title > filename.xml
+ ./mega-export.php --wiki=WIKI --file=out.xml [OPTIONS] Page_title
 Allowed OPTIONS:
  --wiki=VALUE          Available wikis: itwiki, wikidatawiki, commonswiki, metawiki, landscapeforwiki
  --limit=VALUE         Number of revisions for each request
  --file=VALUE          Output filename
  --help|-h             Show this help and quit
 ```
 
 E.g. to download the full history of the [Software libero](https://it.wikipedia.org/wiki/Software_libero) page:
 
 ```
-./mega-export.php --wiki=itwiki "Alessandro Manzoni" > manzoni.xml
+./mega-export.php --wiki=itwiki --file=manzoni.xml "Alessandro Manzoni"
 ```
 
 Note that actually the official MediaWiki/XML format is actually mistreated at least for the heading section: you will not obtain the namespace list, the wiki name, and other unuseful things. Just revisions. Much revisions.
diff --git a/tools/mega-export.php b/tools/mega-export.php
index 3256f2e..e410cb2 100755
--- a/tools/mega-export.php
+++ b/tools/mega-export.php
@@ -1,156 +1,217 @@
 #!/usr/bin/php
 <?php
 # Copyright (C) 2019 Valerio Bozzolan
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License as published by
 # the Free Software Foundation, either version 3 of the License, or
 # (at your option) any later version.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 # GNU Affero General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 // exit if not CLI
 $argv or exit( 1 );
 
 // load boz-mw
 require __DIR__ . '/../autoload.php';
 
+// the number '500' gives to much <This result was truncated because it would otherwise be larger than the limit of 12,582,912 bytes>
+$DEFAULT_LIMIT = 100;
+
 // load configuration
 include 'config.php';
 
 use \cli\Log;
 use \cli\Input;
 use \cli\Opts;
 use \cli\Param;
 use \cli\ParamFlag;
 use \cli\ParamFlagLong;
 use \cli\ParamValued;
 use \cli\ParamValuedLong;
 use \web\MediaWikis;
 use \mw\API\PageMatcher;
 
 // all the available wiki UIDs
 $mediawiki_uids = [];
 foreach( MediaWikis::all() as $site ) {
 	$mediawiki_uids[] = $site::UID;
 }
 $mediawiki_uids = implode( ', ', $mediawiki_uids );
 
 // register all CLI parameters
 $opts = new Opts( [
 	new ParamValuedLong( 'wiki',          "Available wikis: $mediawiki_uids" ),
 	new ParamValuedLong( 'limit',         "Number of revisions for each request" ),
 	new ParamValuedLong( 'file',          "Output filename" ),
 	new ParamFlag(       'help',    'h',  "Show this help and quit" ),
 ] );
 
 $messages = [];
 
 // choosen wiki
 $wiki_uid = $opts->getArg( 'wiki' );
 if( !$wiki_uid ) {
 	$messages[] = "Please specify --wiki=WIKI";
 }
 
 // page titles
 $page_titles = Opts::unnamedArguments();
 if( !$page_titles ) {
 	$messages[] = "Please specify some page titles";
 }
 
-$limit = $opts->getArg( 'limit', 500 );
+// output filename
+$filename = $opts->getArg( 'file' );
+if( !$filename ) {
+	$messages[] = "Please specify a filename";
+}
+
+$limit = (int) $opts->getArg( 'limit', $DEFAULT_LIMIT );
 
 // show the help
 $show_help = $opts->getArg( 'help' );
 if( $show_help ) {
 	$messages = [];
 } else {
 	$show_help = $messages;
 }
 
 if( $show_help ) {
-	echo "Usage:\n {$argv[ 0 ]} --wiki=WIKI [OPTIONS] Page_title > filename.xml\n";
+	echo "Usage:\n {$argv[ 0 ]} --wiki=WIKI --file=out.xml [OPTIONS] Page_title\n";
 	echo "Allowed OPTIONS:\n";
 	foreach( $opts->getParams() as $param ) {
 		$commands = [];
 		if( $param->hasLongName() ) {
 			$commands[] = '--' . $param->getLongName();
 		}
 		if( $param->hasShortName() ) {
 			$commands[] = '-' . $param->getShortName();
 		}
 		$command = implode( '|', $commands );
 		if( $command && ! $param->isFlag() ) {
 			$command .= $param->isValueOptional()
 				? '=[VALUE]'
 				: '=VALUE';
 		}
 		printf( ' % -20s ', $command );
 		if( $param->hasDescription() ) {
 			echo ' ' . $param->getDescription();
 		}
 		echo "\n";
 	}
 	foreach( $messages as $msg ) {
 		echo "\nError: $msg";
 	}
 	echo "\n";
 	exit( $opts->getArg( 'help' ) ? 0 : 1 );
 }
 
+// try to open the file
+$file = fopen( $filename, 'w' );
+if( !$file ) {
+	Log::error( "Can't open file '$filename'" );
+	exit( 1 );
+}
+
 $wiki = MediaWikis::findFromUID( $wiki_uid );
 $wiki->login();
 
 $requests = $wiki->createQuery( [
 	'action' => 'query',
 	'titles' => $page_titles,
 	'prop'   => 'revisions',
 	'rvprop' => [
 		'ids',
 		'flags',
 		'timestamp',
 		'user',
 		'userid',
 		'size',
 		'slotsize',
 		'sha1',
 		'comment',
 		'content',
 	],
 	'rvslots' => 'main',
 	'rvlimit' => $limit,
 ] );
 
-?>
-<mediawiki xmlns="http://www.mediawiki.org/xml/export-0.10/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mediawiki.org/xml/export-0.10/ http://www.mediawiki.org/xml/export-0.10.xsd" version="0.10" xml:lang="it">
-<?php foreach( $requests as $request ): ?>
-	<?php foreach( $request->query->pages as $page ): ?>
-		<?php foreach( $page->revisions as $revision ): ?>
-			<?php if( empty( $revision->comment ) ) continue ?>
-			<?php foreach( $revision->slots as $slot ): ?>
-				<?php if( empty( $slot->contentmodel ) ) continue ?>
-				<revision>
-					<id><?=        $revision->revid ?></id>
-					<parentid><?=  $revision->parentid ?></parentid>
-					<timestamp><?= $revision->timestamp ?></timestamp>
-					<contributor>
-						<username><?= htmlentities( $revision->user ) ?></username>
-						<id><?=       htmlentities( $revision->userid ) ?></id>
-					</contributor>
-					<comment><?= htmlentities( $revision->comment ) ?></comment>
-					<model><?=   htmlentities( $slot->contentmodel ) ?></model>
-					<format><?=  htmlentities( $slot->contentformat ) ?></format>
-					<text xml:space="preserve" bytes="<?= $slot->size ?>"><?= htmlentities( $slot->{'*'} ) ?></text>
-					<sha1><?= htmlentities( $revision->sha1 ) ?></sha1>
-				</revision>
-			<?php endforeach ?>
-		<?php endforeach ?>
-	<?php endforeach ?>
-<?php endforeach ?>
-</mediawiki>
+// total number of revisions
+$total = 0;
+
+// do not print to the out
+$out  = '<mediawiki xmlns="http://www.mediawiki.org/xml/export-0.10/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mediawiki.org/xml/export-0.10/ http://www.mediawiki.org/xml/export-0.10.xsd" version="0.10" xml:lang="it">' . "\n";
+foreach( $requests as $request ) {
+
+	foreach( $request->query->pages as $page ) {
+
+		if( isset( $page->missing ) ) {
+			Log::error( "Page '{$page->title}' is missing" );
+			exit( 1 );
+		}
+
+		$alert_much_revisions = true;
+		foreach( $page->revisions as $i => $revision ) {
+
+			// avoid nonsense revisions
+			if( empty( $revision->comment ) ) {
+				if( $alert_much_revisions ) {
+					$count = count( $page->revisions );
+					if( $count !== $limit ) {
+						Log::warn( "response with $count revisions instead of $limit: consider to lower your limit" );
+						$alert_much_revisions = false;
+					}
+				}
+				continue;
+			}
+
+			$total++;
+
+			foreach( $revision->slots as $slot ) {
+
+				// avoid nonsense slots
+				if( empty( $slot->contentmodel ) ) {
+					continue;
+				}
+
+				$safe_user    = htmlentities( $revision->user      );
+				$safe_userid  = htmlentities( $revision->userid    );
+				$safe_comment = htmlentities( $revision->comment   );
+				$safe_model   = htmlentities( $slot->contentmodel  );
+				$safe_format  = htmlentities( $slot->contentformat );
+				$safe_text    = htmlentities( $slot->{'*'}         );
+
+				$out .= "<revision>\n";
+					$out .= "\t<id>{$revision->revid}</id>\n";
+					$out .= "\t<parentid>{$revision->parentid}</parentid>\n";
+					$out .= "\t<timestamp>{$revision->timestamp}</timestamp>\n";
+					$out .= "\t<contributor>\n";
+						$out .= "\t\t<username>$safe_user</username>\n";
+						$out .= "\t\t<id>$safe_userid</id>\n";
+					$out .= "\t</contributor>\n";
+					$out .= "\t<comment>$safe_comment ?></comment>";
+					$out .= "\t<model>$safe_model</model>\n";
+					$out .= "\t<format>$safe_format</format>\n";
+					$out .= "\t<text xml:space=\"preserve\" bytes=\"{$slot->size}\">$safe_text</text>\n";
+					$out .= "\t<sha1>{$revision->sha1}</sha1>\n";
+				$out .= "</revision>\n";
+			}
+		}
+	}
+
+	// write the file in chunks
+	fwrite( $file, $out );
+	$out = '';
+}
+
+Log::info( "you mega-exported $total revisions! nice shot!" );
+
+fwrite( $file, "</mediawiki>\n" );
+fclose( $file );