diff --git a/classes/helper.php b/classes/helper.php
index 4d7f4d1..45c5740 100644
--- a/classes/helper.php
+++ b/classes/helper.php
@@ -36,14 +36,25 @@ class helper {
      *
      * @param string $table The table to search.
      * @param array $searchingcolumns The columns to search.
+     * @param array $skiptables The tables to skip.
+     * @param array $skipcolumns The columns to skip.
      * @param string $searchstring The string to search for.
      * @return array The columns to search.
      */
-    public static function get_columns(string $table, array $searchingcolumns = [], string $searchstring = ''): array {
+    public static function get_columns(string $table, array $searchingcolumns = [],
+                                       array $skiptables = [], array $skipcolumns = [], string $searchstring = ''): array {
         global $DB;
+
+        // Skip tables that are in the skip list.
+        if (in_array($table, $skiptables)) {
+            return [];
+        }
+
+        // Get the columns in the table.
         $columns = $DB->get_columns($table);
 
         // Make sure the table has id field.
+        // There could be some custom tables that do not have id field.
         $hasid = false;
         foreach ($columns as $col) {
             if ($col->name == 'id') {
@@ -57,13 +68,10 @@ public static function get_columns(string $table, array $searchingcolumns = [],
             return [];
         }
 
-        // Knowns tables to skip.
-        $skiptables = ['grade_grades_history'];
-
-        // Skip tables that are in the skip list.
-        if (in_array($table, $skiptables)) {
-            return [];
-        }
+        // Skip columns that are in the skip list.
+        $columns = array_filter($columns, function($col) use ($skipcolumns) {
+            return !in_array($col->name, $skipcolumns);
+        });
 
         // Only search the specified columns.
         foreach ($searchingcolumns as $column) {
@@ -84,12 +92,9 @@ public static function get_columns(string $table, array $searchingcolumns = [],
             return $col->meta_type === 'X' || $col->meta_type === 'C';
         });
 
-        // Known columns to skip.
-        $skipcolumns = ['introformat'];
-
-        // Skip columns that are in the skip list.
-        $columns = array_filter($columns, function($col) use ($skipcolumns) {
-            return !in_array($col->name, $skipcolumns);
+        // Skip columns which has 'format' in the name.
+        $columns = array_filter($columns, function($col) {
+            return strpos($col->name, 'format') === false;
         });
 
         // Exclude columns that has max length less than the search string.
@@ -108,9 +113,14 @@ public static function get_columns(string $table, array $searchingcolumns = [],
      * Build searching list
      *
      * @param string $tables A comma separated list of tables and columns to search.
+     * @param string $skiptables A comma separated list of tables to skip.
+     * @param string $skipcolumns A comma separated list of columns to skip.
+     * @param string $searchstring The string to search for, used to exclude columns having max length less than this.
+     *
      * @return array
      */
-    public static function build_searching_list(string $tables = '', string $searchstring = ''): array {
+    public static function build_searching_list(string $tables = '', string $skiptables = '', string $skipcolumns = '',
+                                                string $searchstring = ''): array {
         global $DB;
 
         // Build a list of tables and columns to search.
@@ -153,11 +163,15 @@ public static function build_searching_list(string $tables = '', string $searchs
             }
         }
 
+        // Skip tables and columns.
+        $skiptables = explode(',', $skiptables);
+        $skipcolumns = explode(',', $skipcolumns);
+
         // Return the list of tables and actual columns to search.
         $count = 0;
         $actualsearchlist = [];
         foreach ($searchlist as $table => $columns) {
-            $actualcolumns = self::get_columns($table, $columns, $searchstring);
+            $actualcolumns = self::get_columns($table, $columns, $skiptables, $skipcolumns, $searchstring);
             sort($actualcolumns);
             $count += sizeof($actualcolumns);
             if (!empty($actualcolumns)) {
@@ -199,10 +213,9 @@ public static function find_course_field(string $table): string {
      * @param string $search The text to search for.
      * @param string $table The table to search.
      * @param database_column_info $column The column to search.
-     * @param int $limit The maximum number of results to return.
-     * @param $stream The resource to write the results to. If null, the results are returned.
+     * @param bool $summary Whether to return a summary of the search.
+     * @param null $stream The resource to write the results to. If null, the results are returned.
      * @return array The results of the search.
-     * @throws \dml_exception
      */
     public static function plain_text_search(string $search, string $table,
                                              database_column_info $column, bool $summary = false,
@@ -273,8 +286,8 @@ public static function plain_text_search(string $search, string $table,
      * @param string $search The regular expression to search for.
      * @param string $table The table to search.
      * @param database_column_info $column The column to search.
-     * @param int $limit The maximum number of results to return.
-     * @param $stream The resource to write the results to. If null, the results are returned.
+     * @param bool $summary Whether to return a summary of the search.
+     * @param null $stream The resource to write the results to. If null, the results are returned.
      * @return array
      */
     public static function regular_expression_search(string $search, string $table,
diff --git a/cli/find.php b/cli/find.php
index f5a16fb..5c64df9 100644
--- a/cli/find.php
+++ b/cli/find.php
@@ -36,7 +36,7 @@
 Options:
 --search=STRING                  Required if --regex-match is not specified. String to search for.
 --regex-match=STRING             Required if --search is not specified. Use regular expression to match the search string.
---output=FILE                    Required. .Output file. If not specified, output to stdout.
+--output=FILE                    Required output file. If not specified, output to stdout.
 --tables=tablename:columnname    Tables and columns to search. Separate multiple tables/columns with a comma.
                                  If not specified, search all tables and columns.
                                  If specify table only, search all columns in the table.
@@ -44,6 +44,12 @@
                                     --tables=user:username,user:email
                                     --tables=user,assign_submission:submission
                                     --tables=user,assign_submission
+--skip-tables=tablenname         Tables to skip. Separate multiple tables with a comma.
+                                 Example:
+                                    --skip-tables=user,config
+--skip-columns=columnname        Columns to skip. Separate multiple columns with a comma.
+                                 Example:
+                                    --skip-columns=firstname,lastname
 --summary                        Summary mode, only shows column/table where the text is found.
                                  If not specified, run in detail mode, which shows the full text where the search string is found.
 -h, --help                       Print out this help.
@@ -55,12 +61,14 @@
 
 list($options, $unrecognized) = cli_get_params(
     [
-        'search'  => null,
-        'regex-match'  => null,
-        'output'  => null,
-        'tables' => '',
-        'summary' => false,
-        'help'    => false,
+        'search'        => null,
+        'regex-match'   => null,
+        'output'        => null,
+        'tables'        => '',
+        'skip-tables'   => '',
+        'skip-columns'  => '',
+        'summary'       => false,
+        'help'          => false,
     ],
     [
         'h' => 'help',
@@ -95,8 +103,11 @@
     }
     $tables = validate_param($options['tables'], PARAM_RAW);
     $output = validate_param($options['output'], PARAM_RAW);
+    $skiptables = validate_param($options['skip-tables'], PARAM_RAW);
+    $skipcolumns = validate_param($options['skip-columns'], PARAM_RAW);
+    $summary = validate_param($options['summary'], PARAM_RAW);
 } catch (invalid_parameter_exception $e) {
-    cli_error(get_string('invalidcharacter', 'tool_advancedreplace'));
+    cli_error(get_string('errorinvalidparam', 'tool_advancedreplace'));
 }
 
 // Start output.
@@ -110,7 +121,7 @@
 }
 
 // Perform the search.
-[$count,$searchlist] = helper::build_searching_list($tables, );
+[$count, $searchlist] = helper::build_searching_list($tables, $skiptables, $skipcolumns);
 
 $progress = new progress_bar();
 $progress->create();
@@ -124,9 +135,9 @@
 
         // Perform the search.
         if (!empty($options['regex-match'])) {
-            helper::regular_expression_search($search, $table, $column, $options['summary'], $fp);
+            helper::regular_expression_search($search, $table, $column, $summary, $fp);
         } else {
-            helper::plain_text_search($search, $table, $column, $options['summary'], $fp);
+            helper::plain_text_search($search, $table, $column, $summary, $fp);
         }
 
         $columncount++;
diff --git a/lang/en/tool_advancedreplace.php b/lang/en/tool_advancedreplace.php
index b40cbcb..4c7fb9b 100644
--- a/lang/en/tool_advancedreplace.php
+++ b/lang/en/tool_advancedreplace.php
@@ -24,5 +24,6 @@
 
 $string['errorregexnotsupported'] = 'Regular expression searches are not supported by this database.';
 $string['errorsearchmethod'] = 'Please choose one of the search methods: plain text or regular expression.';
+$string['errorinvalidparam'] = 'Invalid parameter.';
 $string['pluginname'] = 'Advanced DB search and replace';
 $string['privacy:metadata'] = 'The plugin does not store any personal data.';