diff --git a/bibtexbrowser-cli.php b/bibtexbrowser-cli.php
new file mode 100644
index 0000000..b53b93d
--- /dev/null
+++ b/bibtexbrowser-cli.php
@@ -0,0 +1,10 @@
+<?php
+// a command line interface for bibtexbrowser
+// example: php bibtexbrowser-cli.php test_cli.bib --id classical --set-title "a new title"
+$_GET['library']=1;
+function createBibEntry() { $x = new RawBibEntry(); return $x;}
+require('bibtexbrowser.php');
+bibtexbrowser_configure('BIBTEXBROWSER_BIBTEX_VIEW','reconstructed');
+bibtexbrowser_configure('BIBTEXBROWSER_BIBTEX_VIEW_FILTEREDOUT','');
+bibtexbrowser_cli($argv);
+?>
diff --git a/bibtexbrowser-documentation.wiki b/bibtexbrowser-documentation.wiki
index 0ec3ff6..5e2116c 100755
--- a/bibtexbrowser-documentation.wiki
+++ b/bibtexbrowser-documentation.wiki
@@ -505,6 +505,14 @@ You must add a ''@string'' block in the bibtex file, which contains the links. T
 }
 </pre>
 
+====How to modify bibtex entries on the command line?====
+
+Use ''bibtexbrowser-cli.php''. For instance:
+
+<pre>
+php bibtexbrowser-cli.php mybib.bib --id classical --set-title \"a new title\" --id with_abstract --set-title \"a new title\" --set-year 1990
+</pre>
+
 =====Related tools=====
 
 Old-fashioned:
diff --git a/bibtexbrowser-test.php b/bibtexbrowser-test.php
index 83e56fa..e5b2927 100755
--- a/bibtexbrowser-test.php
+++ b/bibtexbrowser-test.php
@@ -27,11 +27,14 @@ class BTBTest extends PHPUnit_Framework_TestCase {
   }
   
   function createDB() {
-    $test_data = fopen('php://memory','x+');
-    fwrite($test_data, "@book{aKey,title={A Book},author={Martin Monperrus},publisher={Springer},year=2009}\n"
+    return $this->_createDB("@book{aKey,title={A Book},author={Martin Monperrus},publisher={Springer},year=2009}\n"
     ."@book{aKey/withSlash,title={Slash Dangerous for web servers},author={Ap Ache},publisher={Springer},year=2009}\n"
-    ."@article{aKeyA,title={An Article},author={Foo Bar and Jane Doe},volume=5,journal=\"New Results\",year=2009,pages={1-2}}\n"
-    );
+    ."@article{aKeyA,title={An Article},author={Foo Bar and Jane Doe},volume=5,journal=\"New Results\",year=2009,pages={1-2}}\n");
+  }
+  
+  function _createDB($content) {
+    $test_data = fopen('php://memory','x+');
+    fwrite($test_data, $content);
     fseek($test_data,0);
     $btb = new BibDataBase();
     $btb->update_internal("inline", $test_data);
@@ -487,6 +490,37 @@ class BTBTest extends PHPUnit_Framework_TestCase {
         $this->assertEquals('<a href="http://example.net/">Foo Acé</a>', $authors[1]);
         $this->assertEquals('<a href="http://www.monperrus.net/martin">Monperrus, Martin</a>', $authors[2]);
     }
+    
+    function test_identity() {
+        $btb = new BibDataBase();
+        $btb->load('bibacid-utf8.bib');
+        $nref = count($btb->bibdb);
+        $bibtex = $btb->toBibtex();
+        // reparsing the new content
+        $btb2 = $this->_createDB($bibtex);
+        // there is the same number of entries
+        $this->assertEquals($nref, count($btb2->bibdb));
+        $this->assertEquals($bibtex, $btb2->toBibtex());
+    }
+
+    function test_cli() {    
+        $test_file="test_cli.bib";
+        copy('bibacid-utf8.bib', $test_file);
+        system('php bibtexbrowser-cli.php '.$test_file." --id classical --set-title \"a new title\"");
+        $db = new BibDataBase();
+        $db->load($test_file);
+        $this->assertEquals("a new title", $db->getEntryByKey('classical')->getField('title'));
+        
+        // multiple changes
+        system('php bibtexbrowser-cli.php '.$test_file." --id classical --set-title \"a new title\" --id with_abstract --set-title \"a new title\" --set-year 1990");
+        $db = new BibDataBase();
+        $db->load($test_file);
+        $this->assertEquals("a new title", $db->getEntryByKey('classical')->getField('title'));
+        $this->assertEquals("a new title", $db->getEntryByKey('with_abstract')->getField('title'));
+        $this->assertEquals("1990", $db->getEntryByKey('with_abstract')->getField('year'));
+
+        unlink($test_file);
+    }
 
 } // end class
 
diff --git a/bibtexbrowser.php b/bibtexbrowser.php
index 33b3626..5b5e24b 100755
--- a/bibtexbrowser.php
+++ b/bibtexbrowser.php
@@ -1905,6 +1905,12 @@ class BibEntry {
 
 } // enc class BibEntry
 
+class RawBibEntry extends BibEntry {
+  function setField($name, $value) {
+    $this->fields[$name]=$value;
+  }
+}
+
 /** returns an HTML tag depending on BIBTEXBROWSER_LAYOUT e.g. <TABLE> */
 function get_HTML_tag_for_layout() {
   switch(BIBTEXBROWSER_LAYOUT) { /* switch for different layouts */
@@ -3778,7 +3784,7 @@ class BibDataBase {
   /** Adds a new bib entry to the database. */
   function addEntry($entry) {
     if (!$entry->hasField('key')) {
-      die('error: a bibliographic entry must have a key');
+      die('error: a bibliographic entry must have a key '.$entry->getText());
     }
     // we keep its insertion order
     $entry->order = count($this->bibdb);
@@ -3875,6 +3881,13 @@ class BibDataBase {
       }
       return $result;
   }
+  
+  function toBibtex() {
+    $s = "";
+    foreach($this->bibdb as $bibentry) { $s.=$bibentry->getText()."\n"; }
+    return $s;
+  }
+  
 } // end class
 
 /** returns the default CSS of bibtexbrowser */
@@ -4679,6 +4692,25 @@ class Dispatcher {
 
 } // end class Dispatcher
 
+function bibtexbrowser_cli($arguments) {
+  $db = new BibDataBase();
+  $db->load($arguments[1]);
+  $current_entry=NULL;
+  $current_field=NULL;
+  for ($i=2;$i<count($arguments); $i++) {
+    $arg=$arguments[$i];
+    if ($arg=='--id') {
+      $current_entry = $db->getEntryByKey($arguments[$i+1]);
+      $i=$i+1;
+    }
+    if (preg_match('/^--set-(.*)/',$arg,$matches)) {
+      $current_entry->setField($matches[1],$arguments[$i+1]);
+      $i=$i+1;
+    }
+  }
+  file_put_contents($arguments[1],$db->toBibtex());
+}
+
 } // end if (!defined('BIBTEXBROWSER'))
 
 @include(preg_replace('/\.php$/','.after.php',__FILE__));