--- /dev/null	2020-01-02 04:43:18.583999853 +0000
+++ new/src/share/classes/jdk/jfr/internal/tool/Help.java	2020-01-30 06:27:44.969222286 +0000
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code 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 General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.jfr.internal.tool;
+
+import java.io.PrintStream;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Deque;
+import java.util.List;
+
+final class Help extends Command {
+
+    @Override
+    public String getName() {
+        return "help";
+    }
+
+    @Override
+    public List<String> getOptionSyntax() {
+        return Collections.singletonList("[<command>]");
+    }
+
+    protected List<String> getAliases() {
+        return Arrays.asList("--help", "-h", "-?");
+    }
+
+    @Override
+    public void displayOptionUsage(PrintStream stream) {
+        println("  <command>   The name of the command to get help for");
+    }
+
+    @Override
+    public String getDescription() {
+        return "Display all available commands, or help about a specific command";
+    }
+
+    @Override
+    public void execute(Deque<String> options) throws UserSyntaxException, UserDataException {
+        if (options.isEmpty()) {
+            Command.displayHelp();
+            return;
+        }
+        ensureMaxArgumentCount(options, 1);
+        String commandName = options.remove();
+        Command c = Command.valueOf(commandName);
+        if (c == null) {
+            throw new UserDataException("unknown command '" + commandName + "'");
+        }
+        println(c.getTitle());
+        println();
+        c.displayUsage(System.out);
+    }
+}