Software Development

Software Development, software engineering , computer science

Valgrind 3.16.0 for MacOS Mojave 10.14.6

After many unstable versions and unsuccessful tries found a working but still experimental solution for MacOS Mojave 1.14.6 using homebrew. This solution also working with Qt5.14.1 using QtCreator 4.11.2 on Mojave 10.14.6.

My conclusion after carry out some analysis on some of my cross platform projects, simple and more complicated once. This solution works on simple projects, however as the complexity increases the results are totally unpredictable.

I’d like to emphasise that after comparing my results, I still NOT recommend to rely on results running Valgrind on MacOS, found fairly high number of critical errors and false positives. My results based on comparing the two following development environments:

– MacOS Mojave 10.14.6, Valgrind 3.16.0, Qt5, gcc, clang
– Ubuntu 18.04, Valgrind 3.16.0, Qt5, gcc, clang

If you choose to protect yourself against tracking, surveillance, and censorship our onion mirror is live

Dear visitor, you can also find our blog on the Tor network at http://goyyh6reeibixtlo.onion/. A free software Tor Browser will be required to access onion sites. Some people asked me about why I don’t have an onion mirror of my blog. I did not feel the need of it, but as it sounded like a request here it is, from now you can protect yourself against tracking, surveillance, and censorship.
Thanks for visiting my site.

How to clear your DNS cache on OSX 10.10.4 or above

MacOS® 10.10.4 and above
To clear your DNS cache if you use MacOS X version 10.10.4 or above, perform the following steps:

Click Applications.
Click Utilities.
Click Terminal.
Run the following command:

Or on Microsoft Windows version 7, 8, 10 type the following command to the command prompt:


[PHP] How to return IP address of a host / domain

Here is a quick solution written in php that you can use to determine the current IP address of a given webhost/domain.

[Linux] Install WordPress on Ubuntu Server with add-on features as HTTPS support, SSL certificate and HTTP2 supports

Enable HTTPS supports:

Create a ssl-params.conf file and add the following definition below to it, then save it.

Next thing to do is create a backup of the original default-ssl.conf file.

Then modify it accordingly, we are deploying a wordpress site in this particular example we use the following adjustments.

Enable HTTP2 supports:

It is also recommended adding strong ciphers for Apache to increase SSL Security on the server.
Part of my Best Practices to deploy a secure webserver, virtual personal server or database serve is to add the recommended ciphers from

Install Oracle Java 12 on Ubuntu

You need to add the PPA. (Surce: “Linux Uprising” team)

For multiple java versions, install [or uninstall] oracle-java12-set-default package to set [or not] Java 12 as default.

Remove it: … use the following command if you need to uninstall it:

Sourcetrail a cross-platform source explorer for C/C++ and Java*

Sourcetrail a cross-platform source explorer, great and powerful tool to have it.
I personally recommend it for any junior or senior developers. A cross-platform source explorer for C/C++ and Java* deserves a blog post to reach more developers as well as serious commercial customers.

Watch Sourcetrail on Youtube

* Free for non-commercial use

youtube-dl arguments

Best Audio Quality for mp3 (with –ffmpeg-location):

Best Audio/Video Quality for mp4 (with –ffmpeg-location):

How to use wget without adding –no-check-certificate

You need to add a check_certificate = off line into your .wgetrc file in your Home directory.
Or simply run this command on your terminal.

After this wget will add this –no-check-certificate automatically from your .wgetrc file.

BTCPayServer the self-hosted payment processor for Bitcoin and other cryptocurrencies.

How does it works?

BTCPay Server is a self-hosted and automated invoicing system. When checking out, the customer is presented with an invoice. Each time, a different address is tied to a particular invoice, so there is no address re-use. BTCPay follows the status of the invoice through the blockchain and informs a merchant when he can fulfil the order safely.

BTCPay is a code, not a company. There is no third-party between a merchant and a customer. Merchant is always in full control of the funds. There are no processing or subscription fees. BTCPay Server is free to use and completely open-source, so developers or security auditors can always inspect the quality of the code.

Source code:

SQLite – How to use fundamental functions in C++

SQLite operations in C++
This tutorial aimed to demonstrate how to use SQLite database operations such as CREATE, INSERT, UPDATE, SELECT and DELETE in C++. Since the appearance first smartphone and other mobile devices SQLite become most widely deployed and used database engine in the world. Precise numbers are difficult to obtain but SQLite is likely used more than all other database engines combined. We can find SQLite in every Android device, iPhone and iOS device, Mac, Windows10, Firefox, Chrome, Safari, Skype, Dropbox, TurboTax, QuickBooks, PHP, Python, television sets, set-top cable boxes and many automotive multimedia systems.

It’s an open-source SQL database engine. You can download the source code or precompiled binaries depending your requirements. You might also need to add [-lsqlite3] and [-std=c++17] to successfully compile, create an executable file. Each of the following source code available on my git repository.

Use this link local_db.sqlite (173 downloads) if you would like to download the local_db.sqlite file that I used in this tutorial.

Step 1 – The first thing we need to do is to create the actual database file that we will use in this article. I called sqltdemo.db in our case.

Compile and run our source code to create the local_db.sqlite with the following command. Here we link our code with the sqlite3 library that will create our db file.

Verify our result:


Compile and run.


Compile and run.

Step 4 – Fetch and display records from the company CANDIDATE TABLE. In this scenario we use a callback function that obtains results from SELECT statement.

Compile and run.

Step 5 – Using UPDATE statement to update any records in our CANDIDATE table.

Compile and run.

Step 6 – DELETE statement can delete any records from the CANDIDATE table.

Compile and run.

I recommend you to check the official SQLite documentation at for more advance SQLite features and options and support. For further info about using sql with c++ you might found it useful to read me previous post of  a simple Qt tool to test QSqlDatabase access connection to a MySQL database. I created this simple Qt command line tool to test connection between Qt client applications and a remote Mysql Server. The code includes Secure Sockets Layer (SSL) support to test secure connection. The QSqlDatabase class provides an interface for accessing a database through a connection where an instance of QSqlDatabase represents the connection. The connection provides access to the database via one of the supported database drivers, which are derived from QSqlDriver.

Alternatively, we can subclass your own database driver from QSqlDriver. My next post will be an article how to write your own database driver in Qt for Unix, OSX and Windows platforms.

[WWW] Web development tools

Here is a list of web development tools I mostly use, these tools are coming very useful especially to analyze, tune and optimize your web project. These are essential tools to achieve the best user experience and highest performance.

[C++] MemorySanitizer

MemorySanitizer is a detector of uninitialized memory reads in C/C++ programs. Uninitialized values occur when stack- or heap-allocated memory is read before it is written. MSan detects cases where such values affect program execution.
At this time, MemorySanitizer supports Linux x86_64 only.
To use MemorySanitizer, compile and link your program with -fsanitize=memory -fPIE -pie. To get any stack traces, add -fno-omit-frame-pointer.

Origins tracking

[C++] AddressSanitizer

AddressSanitizer is a memory error detector for C/C++. It finds:

-Use after free (dangling pointer dereference)
-Heap buffer overflow
-Stack buffer overflow
-Global buffer overflow
-Use after return
-Use after scope
-Initialization order bugs
-Memory leaks

In order to use AddressSanitizer we will need to compile and link your program using clang with the -fsanitize=address switch. To get a reasonable performance add -O1 or higher.

[C++] ThreadSanitizer

ThreadSanitizer is a data race detector for C/C++. Data races are one of the most common and hardest to debug types of bugs in concurrent systems.
Here is an example of a data race that can lead to crashes and memory corruptions:

[C++] How to install gcc-7 on Ubuntu LTS 16.04

[C++] Return absolute_path using boost::filesystem

Return absolute_path using boost::filesystem

You’ll need to add the boost libraries to the linking phase with the -L flag and the names of the libraries with the -l flag. This is different from the compilation phase where only the -I include path is needed. For example in my case:

boost::filesystem tutorials

The Boost C++ Libraries


CMake has a CMAKE_BUILD_TYPE option for predefined build types. The build type affects optimization and whether the result of the build is debuggable. Those used by MySQL are RelWithDebInfo or Debug.
RelWithDebInfo (optimizations are on, debug info is generated) is used in MySQL by default.
Debug (optimizations are off, debug info is generated) is used if the WITH_DEBUG option is set.

CMAKE_BUILD_TYPE is not set when custom compile flags are used

To define which C and C++ compilers to use, you can define the CC and CXX environment variables. For example:

To specify your own C and C++ compiler flags, for flags that do not affect optimization, use the CMAKE_C_FLAGS and CMAKE_CXX_FLAGS CMake options:

When providing your own compiler flags, you might want to specify CMAKE_BUILD_TYPE as well.
For example, to create a 32-bit release build on a 64-bit Linux machine, do this:

If you set flags that affect optimization (-Onumber), you must set the CMAKE_C_FLAGS_build_type and/or CMAKE_CXX_FLAGS_build_type options, where build_type  corresponds to the CMAKE_BUILD_TYPE value.

To specify a different optimization for the default build type (RelWithDebInfo) set the CMAKE_C_FLAGS_RELWITHDEBINFO and CMAKE_CXX_FLAGS_RELWITHDEBINFO options.
For example, to compile on Linux with -O3 and with debug symbols, do this:


List of build-specific variants to specify your Qt project.

QSqlDatabase connection testing tool

QSqlDatabase connection access

A simple command line tool to test connection between Qt client applications and a remote Mysql Server. The code includes Secure Sockets Layer (SSL) support to test secure connection. The QSqlDatabase class provides an interface for accessing a database through a connection. An instance of QSqlDatabase represents the connection. The connection provides access to the database via one of the supported database drivers (MySQL in our case), which are derived from QSqlDriver. Alternatively, we can subclass your own database driver from QSqlDriver. I’ll post an another article about how to write your own database driver in Qt for Unix, OSX and Windows platforms. It’s recommend to write your own database driver especially when you planning to deploy your application in different platforms. It’s simply because there could be surprises especially on client deploying your application that using one of the supported database drivers due to missing dependencies or environmental variables.

Software prerequisites:
Remote MySQL server version: 5.7 or above
Qt version: Qt_5_7_1 or above
OpenSSL 1.0.x or above the for SSL feature

How to use it:
1. I simply run the mysql_conn_test_database.sql SQL script file to create a test database on the remote server.
2. Set the hostname or IP, port number, username and password. You migth need to create a new database user for this purpose.
[You will need to create SSL certificates for the database server and client in order to test SSL Feature on the MySQL Server.]
3. If everthing is set just simple build and run the project in your QtCreator.

If everything goes well you will recieve the following feedback from your terminal:

QSqlDatabase connection test tool was created and written by Roland Ihasz and it is licensed under the GNU General Public License (GPL) Version 2 or above.

Check out on GitHub.



Alternatively, use the following shorter source code to check the connection without any sql query.
 QSqlDatabase connection test tool without query


After spending a quite a bit of time to find the solution of this often-occurring
QMYSQL driver not loaded problem mainly after installing Qt installation in a new software environment, So I thought I am going to share my best practice to fix this issue.
I wasn’t able to establish database connection even if I received the list of available drivers:

QSqlDatabase: available drivers: QSQLITE QMYSQL QMYSQL3 QODBC QPSQL
QSqlDatabase: QMYSQL driver not loaded

The following simple method helps to fix the problem.
On OSX system just simple install or re-install mysql using the flowing command. I usually prefer Homebrew as it fulfils most my requirements and using MacPort when I really no other options available.

then place the following (223 downloads) file to the path below:

On different Linux distributions I usually apt install or yum install the MySQL package basically the only thing I need to make sure that place the (223 downloads) file to the following path:

This method solves the QMYSQL driver not loaded issue and allows me to establish database connection, it might work on Windows system as well, however I had not opportunity to try before.
Please, let me know if this method also working for you by dropping a line.

Download: (223 downloads)

Variable Sized Arrays – HackerRank Challenge Solved in C++

Variable Sized Arrays – HackerRank Challenge Solved in C++

HackerRank C++ Virtual Functions Challenge

HackerRank C++ Virtual Function Challenge

HackerRank Challenge – Find out the area of a rectangle using C++ inheritance

Rectangle Area HackerRank Challenge

..and a bit longer version.

How to display an image on a QtWidget

There is a simple method to insert images such as a png file using QPixmap. I personally prefer to use a QLabel to show simple images on QWidget, particularry if there is no any other fancy requirements.
Basically you can locate the QLabel anywhere on your QWidget. You will find the pixelmap option at the text option section in your Qt Creator, right below the textFormat. When you click on the Value section you’ll find a small arrow pointing down.
Simple click on it, then choose your png file.

If you just simple want to display an image to the QWidget, I found the following option works well. You just need to insert the path of the image file right after the

member function in your main parent widget, then insert the following source code.

If you know other method to display an image on a QtWidget Please, let me know by dropping a line, I can add it to this post if it is relevant and you agree to do.

Top software developer blogs

6) /\NDY
Herding Cats

… and some great once on Data Science: – Data Science

data science central


IBM big data hub

A curated list of data science blogs

No Free Hunch

David Smith’s blog

Data Science for Social Good


[SOLVED] How to re-flash the corrupted BIOS of a Dell Laptop using a USB drive

This is the latest version of the How re-flash the corrupted BIOS of a Dell Inspiron Laptop article.


There is, however, no guarantee that the following method will also work for you, as reading this sentence you agree that I am taking no responsibility of any damage caused by the following procedure.

How to Recover from a disastrous BIOS update?
How to Flash a Corrupted Dell Inspiron Laptop BIOS?

Simply follow this procedure to re-flash failed BIOS update on a Dell Inspiron (n5010 model in my case) laptop. Presumably the following method also works on almost all other Dell models.

Phase 1.

  • Rename the newly created N5010A15.HDR and N5010A15.ROM files to N5010.HDR and N5010.ROM.
  • Format an USB thumb-drive to FAT and copy the N5010.HDR, N5010.ROM files on it. You do not need to create bootable USB drive.
    *UPDATE: most of the time I hear feedback about this method people add a comment that they formatted their USB thumb-drive to FAT16 as the FAT32 file system did NOT work.

Phase 2.

  • Shutdown your faulty laptop if is is still running with the black screen.
  • Remove the battery
  • Remove the CMOS battery
  • Disconnect the power supply.
  • Insert the USB drive in the USB port.
    *UPDATE: According to the feedback on this method most people use the left USB socket, as the rest of the USB sockets might not functioning at this state.

*Note: There are few cases reported about not active USB ports. Simply try to use other USB port if you notice or suspect that the system cannot read the USB drive from the port you plugged it. Use USB drive with activity LED if you have one, the blinking LED will confirm that the system reads data from your USB drive.

Phase 3.

  • Press and keep hold the END key on the keyboard for your faulty laptop.
  • Plug the DC power connectors (power plug) into the laptop.
  • After a few seconds your faulty laptop will start itself and will re-flash its corrupted BIOS and automatically reboot.
  • You can release the END key after the flashing process started. A USB drive with an activity LED can confirm that the BIOS flashing process started. The complete re-flashing process will take no longer than 60 maximum 90 seconds.

Your comments and suggestions would be greatly appreciated.


I am taking no responsibility of any damage caused by the following NOT TESTED procedure. Try this PhoenixTool method when the /writeromfile and /writehdrfile commands are not give you any result.

This procedure never been tested by myself, however quite a few people were asked me about how to extract ROM files from other system BIOS files without the /writeromfile and /writehdrfile commands mentioned above in my step by step guide. 

Let’s take an example of Inspiron N7010 BIOS. In this case the usual /writeromfile and /writehdrfile commands will not work.
You’ll need 7-Zip or Universal Extractor and PhoenixTool 2.73 (345 downloads) to extract/create rom files from the R301250.exe System BIOS file.

Phase 1.

  • Download the R301250.exe (2969 KB) file from the official source ( )

Phase 2.

Phase 3.

Useful resources:

  1. AT24C01A EEPROM datasheet
  2. DELL EMC System Update for Windows and Linux
  3. Flashrom or Qflashrom
  4. Superiotool – Detect which Super I/O you have on your mainboard
  5. Official Dell BIOS Recovery options
  6. Dell: What is BIOS and How to Download and Install the latest BIOS?
  7. Dell: 64-bit BIOS Installation Utility
  8. RW-Everything
  9. PhoenixTool 2.73 (345 downloads)

The reason behind writing this BIOS recovery article is provide some helpful info/advice/starting point to everyone facing with the same issue. This work (How to re-flash the corrupted BIOS of a Dell Laptop using only a USB drive, by Roland Ihasz) is free of known copyright restrictions.

C++ Standards Support in GCC

GNU has announced the stable release of GNU Compiler Collection 7 (GCC 7), which has been marked with the release of GCC 7.1. This month, the 30-year anniversary of GCC 1.0 will also be celebrated.

C++ Standards Support in GCC
This page is a brief summary of some of the huge number of improvements in GCC 7. For more information, see the Porting to GCC 7 page and the full GCC documentation.

Porting to GCC 7
List of GNU GCC Releases

Qt Creator plugins

Just reIf you just started to familiar yourself with Qt’s IDE, this is my advice. After a long time of daily usage became my favorite developing IDE, as it is covering almost every part of the work I do on a daily basis. However there are three (3rd party) plugins am always adding to my Qt Creator IDE wherever I work on-site or in the office they are very useful. Especially CppCheck but gtest and the DB viewing tool can coming handy.
Qt Creator CppCheck integration plugin
Qt Creator Google C++ Testing Framework integration plugin
Qt Creator SQL database viewer plugin

All of the plugins mentioned above developed by Gres.

Bottom line: a good and comfortable development enviromet setup if playing a key role of utilizing your almost always limited time and result an efficient way of your daily developing work.
Valgrind (adding memory and function profiler feature to Qt Creator), sometimes preferring GDB instead of LLDB especially project on OSX.
I also use Doxygen for generating documentation from annotated C++ sources.
You can enable/disable plugins, I strongly recommend to enable this very convenient plugging, it is much more helpful compare to my previously used tool. It recognizes notes: TODO, BUG, FIXME, NOTE, HACK by default.

Very simply to use. Here is one of my projects TODO list just started.

Click image to zoom inClick image to zoom in

Sort My List

Sort My List an easy to use very handy online tool where You can sort or clean your list in a variety of ways. This simple online tool could help you remove, add, separate data without using other other softwares sorting features. There are limitations in this online tool, and I won’t recommend on large datasets, however in many cases could be very handy, removing unwanted whitespaces or any characters.
Find out more:


Cheerp is a C++ compiler for the Web, based and integrated into the LLVM/clang infrastructure.

With Cheerp you can write Web applications in pure C++ code, or port existing C++ code to the Web. Your C++ code is fully optimized by the LLVM system and it’s compiled into JavaScript code that runs on the browser.

[Linux] Required packages to fix (Missing GL/gl.h) error

The following additional packages required on Ubuntu in order to be able successfully compile qt projects without (Missing GL/gl.h) error message.

NeoVim – “the future of vim” and SpaceVim – the community-driven vim distribution

After trying many light-weight IDE in the past I decided to give NeoVim a whirl. I’ve been using NeoVim for four months now without any issues. If you are a Vim user or just looking for a very light-weight IDE NeoVim is for you.

More powerful plugins. The msgpack API enables structured communication to and from any programming language. Remote plugins run as co-processes that communicate with Neovim safely and asynchronously. User manual:

Better out-of-the-box
-Strong defaults
-Modern terminal features such as truecolor and bracketed paste
-Built-in terminal emulator

First-class embedding, GUIs (or TUIs such as readline) can nvim –embed or communicate via named pipe using the discoverable msgpack API.
Install Now

SpaceVim is a community-driven vim distribution that supports vim and Neovim. SpaceVim manages collections of plugins in layers. Layers make it easy for you, the user, to enable a new language or feature by grouping all the related plugins together. It got inspired by spacemacs.

Linux and macOS one-line installer:

Manual install on Linux and macOS:
Install on other platforms: Installing SpaceVim



htop and glances interactive process viewers for Linux Servers.

This is htop, an interactive process viewer for Unix systems. It is a text-mode application (for console or X terminals) and requires ncurses.
I am using this brilliant app for monitoring my servers and Raspberry Pi. Download

I recommend use PyPi:

Glances – “An Eye on your system”
Glances is a cross-platform system monitoring tool. Written in Python, Glances will run on almost any platform : GNU/Linux, FreeBSD, OS X and Windows.

You can enable many useful plugins using the following command.

or with python3

Configuration file options:

Ncdu is also a brilliant command line disk usage analyzer with an ncurses interface.


[PDF] Jenkins The Definitive Guide – Continuous Integration

Continuous Integration is a key element of modern software development best practices. You can learn how to automate your build, integration, release and deployment process with Jenkins from this free ebook.


Download pdf eBook
You can get more information about CI on Eclipse Hudson website where you can read The Hudson Book for free in online, PDF, EPUB formats.

*Request(Please report broken links) Dear Reader, if any of the external links in this post are broken please inform me using the contact us form. Thank you.

Reset mysql root password on unix without needing old password. Raw


Determining your internal and external IP

Commands to find out your external IP:

My favorite one as it returns the following format:
“ip”: “”,
“hostname”: “”,
“city”: “Mountain View”,
“region”: “CA”,
“country”: “US”,
“loc”: “37.4192,-122.0574”,
“org”: “Google Inc.”,
“postal”: “94043”

You can get the same result using curl.

The following command returns the internal IP:

Differences between c++11 vs c++14 standards

I thought I repost two worth reading summarizing article about c++11 and c++14 in my blog.
There is a nice article about the top 10 c++11 features written by Marius Bancila.
I actually quite agree with this article, so if you are interested you can take a look (
There is also a good article about some of the c++14 standards written by Mark Nelson, if you are interested you can take also look (
Finally, there is a c++14 Language Features list on the C++1y/C++14 Support in GCC link.

Bjarne Stroustrup announces C++ Core Guidelines

This morning in his opening keynote at CppCon, Bjarne Stroustrup announced the C++ Core Guidelines (, the start of a new open source project on GitHub to build modern authoritative guidelines for writing C++ code.

The guidelines are designed to be modern, machine-enforceable wherever possible, and open to contributions and forking so that organizations can easily incorporate them into their own corporate coding guidelines.

Read more on the source site: []

In addition you might find very useful to read Bjarne Stroustrup’s C++ Style and Technique FAQ [Updated Modified February 13, 2016]

[C++] Store different types in a single vector


Number Factorizer in C++


C++ program to generate Fibonacci series

Here is my C++ program to generate Fibonacci series.
The Fibonacci sequence is a sequence Fn of natural numbers defined recursively.


How to install java 1.6.31 JRE on Ubuntu (64bit)

lnrsoft@lnrsoft:$cd /opt
lnrsoft@lnrsoft:/opt$sudo mkdir java
lnrsoft@lnrsoft:/opt$cd java
lnrsoft@lnrsoft:/opt/java$sudo mkdir 64
lnrsoft@lnrsoft:/opt/java$sudo mv ~/Desktop/jre-6u31-linux-x64.bin /opt/java/64
lnrsoft@lnrsoft:/opt/java$sudo chmod 755 /opt/java/64/jre-6u31-linux-x64.bin
lnrsoft@lnrsoft/opt/java:$cd /opt/java/64
lnrsoft@lnrsoft:/opt/java/64$sudo ./jre-6u31-linux-x64.bin

Agree the license agreement

lnrsoft@lnrsoft:/opt/java/64$sudo update-alternatives –install “/usr/bin/java” “java” “/opt/java/64/jre1.6.0_31/bin/java” 1
lnrsoft@lnrsoft:/opt/java/64$sudo update-alternatives –set java /opt/java/64/jre1.6.0_31/bin/java

Install the Firefox plugin

lnrsoft@lnrsoft:/opt/java/64$mkdir ~/.mozilla/plugins
lnrsoft@lnrsoft:/opt/java/64$sudo apt-get remove icedtea6-plugin
lnrsoft@lnrsoft:/opt/java/64$rm ~/.mozilla/plugins/
lnrsoft@lnrsoft:/opt/java/64$rm ~/.mozilla/plugins/
lnrsoft@lnrsoft:/opt/java/64$ln -s /opt/java/64/jre1.6.0_31/lib/amd64/ ~/.mozilla/plugins/

Start up and shut down manually Oracle 11g on ubuntu

Start up

lnrsoft@lnrsoft:$cd /home/LnRSoft/Oracle/app/lnr/product/11.1.0/db_1/bin
lnrsoft@lnrsoft:~/Oracle/app/lnr/product/11.1.0/db_1/bin$ ./lsnrctl start
Services Summary…
Service “lnr” has 1 instance(s).
Instance “lnr”, status.
The command completed successfully

lnrsoft@lnrsoft:~/Oracle/app/lnr/product/11.1.0/db_1/bin$./sqlplus / as sysdba
SQL*Plus: Release – Production on Wed Oct 20 21:10:07 2010
Copyright (c) 1982, 2007, Oracle. All rights reserved.
Connected to an idle instance.
ORACLE instance started.
Total System Global Area 841162752 bytes
Fixed Size 1303160 bytes
Variable Size 444599688 bytes
Database Buffers 390070272 bytes
Redo Buffers 5189632 bytes
Database mounted.
Database opened.
SQL> exit;

lnrsoft@lnrsoft:~/Oracle/app/lnr/product/11.1.0/db_1/bin$ ./emctl start dbconsole
Oracle Enterprise Manager 11g Database Control Release
Copyright (c) 1996, 2007 Oracle Corporation. All rights reserved.
Starting Oracle Enterprise Manager 11g Database Control ………… started.

Shut down

lnrsoft@lnrsoft:~/Oracle/app/lnr/product/11.1.0/db_1/bin$ ./emctl stop dbconsole
Stopping Oracle Enterprise Manager 11g Database Control … Stopped.
lnrsoft@lnrsoft:~/Oracle/app/lnr/product/11.1.0/db_1/bin$./sqlplus / as sysdba
SQL*Plus: Release – Production on Wed Oct 20 21:58:12 2010
Copyright (c) 1982, 2007, Oracle. All rights reserved.
Connected to an idle instance.
SQL>shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> exit;

Disconnected from Oracle Database 11g Enterprise Edition Release – Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
lnrsoft@lnrsoft:~/Oracle/app/lnr/product/11.1.0/db_1/bin$ ./lsnrctl stop

The command completed successfully

RemoteOperationException: ERROR: Invalid username and/or password

For Host Credentials Setup – NOT connected to a Domain:
username = user_name
password = pass_word

For Host Credentials Setup – connected to a Domain:
username = domainuser_name
password = pass_word

For Database Credentials Setup:
username = database_user_name
password = database_user_password

For Enterprise Manager logon Screen prompt
username = sysman
password = sysman_password

For Database logon Screen prompt
username = sys (or any database_user_name)
password = sys_password (or any database_user_password)

Set the logon as batch job from local security policy
1. Go to Control Panel, Administrative Tools.
2. Click on Local Security Policy.
3. Local Policies, User Rights Assignment.
4. Double click, ‘Log on as a batch job’

How to install java 1.6.22 JRE on ubuntu

$ cd /opt
$ sudo mkdir java
$ cd java
$ sudo mkdir 32
$ sudo mv ~/Desktop/jre-6u22-linux-i586.bin /opt/java/32
$ sudo chmod 755 /opt/java/32/jre-6u22-linux-i586.bin
$ cd /opt/java/32
$ sudo ./jre-6u22-linux-i586.bin

Agree the license agreement

$ sudo update-alternatives --install "/usr/bin/java" "java" "/opt/java/32/jre1.6.0_22/bin/java" 1
$ sudo update-alternatives --set java /opt/java/32/jre1.6.0_22/bin/java

Install the Firefox plugin

$ mkdir ~/.mozilla/plugins
$ sudo apt-get remove icedtea6-plugin
$ rm ~/.mozilla/plugins/
$ rm ~/.mozilla/plugins/
$ ln -s /opt/java/32/jre1.6.0_22/lib/i386/ ~/.mozilla/plugins/