Posts Tagged ‘environment’

Virtual Keyboard for Linux and other Freedom respecting operating Systems

Monday, July 30th, 2018

Reading Time: 2minutes

How to install and Use Linux Virtual Keyboard and other freedom respecting Operating Systems

  •  Looking for a quick way to use VIRTUAL KEYBOARD ON LINUX COMPUTER OPERATING SYSTEM, you can do it just this 1 task in 3 simple steps  ???
    – Logical question emerges, WHY ??? would you need a virtual keyboard on Free Software OS such as Linux?
    Well, just because sometimes it is much more secure to use a Virtual Keyboard, especially if you have doubt that your keyboard has been tapped or a Key Logger (Sniffer), intercepting the Keyboard IN / OUT jacks, is installed on the computer or you might have sit on a computer of ,a friend running Linux, and you want to make sure he did not install sniffer to intercept your ,SSH login passwords and ,later hack into your Servers, after stealing, the password

 

  • Assuming you're on : – Debian / Ubuntu Linux, or other of the numerous IT systems such as ,FreeBSD / OpeBSD etc. out there, you can run simply this commands:

     

  •  apt-get install –yes florence
    * A. To make it, easily invokable for laters, create a small bash, shell script in directory; – location /usr/bin/virtual-keyboard like, the one below:

    vim /usr/bin/virtual-keyboard

    * B.. INside the file Place following 1 liner code
     

    #!/bin/sh
    /usr/bin/florence

     

    * C… To later invoke it any time:
    Press ALT + F2 (or use Run Command Dialog in GNOME / KDE / Windomaker / IceWM whatever or any other crazy graphic environment of your choice and run:

    /usr/bin/virtual-keyboard

 

Increase tomcat MaxThreads values to resolve Tomcat timeout issues and sort

Friday, December 11th, 2015

Reading Time: 3minutes

Increase_Tomcat_MaxThreads_values_to_resolve_Tomcat_timeout-issues-and-sort

Thanks God, we have just completed (6 months) Migration few Tomcat and TomEE application servers for PG / PP and Scorpion instances from old environment to a new one for a customer.

Though the separate instances of the old environment are being migrated, the overall design of the Current Mode of Operations (CMO) as they use to call it in corporate World and the Future Mode of Operations (FMO) has differences.

The each of applications on old environment is configured to run in Tomcat failover cluster (2 tomcats on 2 separate machines with unique IP addresses are running) and Apache Reverse Proxy is being used with BalanceMember apache directive in order to drop requests to Tomcat cluster to Tomcat node1 and node2. On the new environment however by design the Tomcat cluster is removed and the application request has to be served by single Tomcat instance.

The migration completed fine and in the beginning in the first day (day 1) and day 2 since the environment went in Production and went through the so-called "GoLive", as called in Corporate World- which is a meathor for launching the application to be used as a production environment for customer, the customer reported TimeOut issues.

Some of the requests according to their report would took up to 4 minutes to serve, after a bit of investigation we found out, that though the environment was moved to one Tomcat the (number) amount of connections to application of end clients did not change, thus the timeouts were caused by default MaxThreads being reached and, we needed to to obviously raise that number. Here is the old Apache RP config where we had the 2 Tomcats between which the RP was load balancing:
 

BalancerMember ajp://10.10.10.5:11010 route=node1 connectiontimeout=10 ttl=60 retry=60
BalancerMember ajp://10.10.10.5:11010 route=node2 connectiontimeout=10 ttl=60 retry=60

ProxyPass / balancer://pool/ stickysession=JSESSIONID
ProxyPassReverse / balancer://pool/


As we needed a work around, we come to conclusion that we just need to increase Timeout on RP first so on Apache Reverse Proxy we placed following httpd.conf Virtualhost ProxyPass (directive) configs :

 

ProxyPass / ajp://10.10.10.5:11010/ keepalive=On timeout=30 connectiontimeout=30 retry=20
ProxyPassReverse / ajp://10.10.10.5:11010/

ProxyPass / ajp://10.10.10.5:11010/ keepalive=On timeout=30 connectiontimeout=30 retry=20
ProxyPassReverse / ajp://10.10.10.5:11010/


and following Apache Timeout directives options:

 

Timeout 300
KeepAlive On
MaxKeepAliveRequests 100
KeepAliveTimeout 15


Even though the developer tried to insist that the problem was in Reverse Proxy timeout config, they were wrong as I checked the RP logs and there was no "maximum connections reached" errors..

As you could guess what left to check was only Tomcat, after quick evaluation of server.xml, it turned out that the MaxThreads directive on old clustered Tomcats was omitted at all, meaning the default MaxThreads Tomcat value of 200 maximum connections were used, however this was not enough as the client was quering the application with about 350 connections / sec.

The solution was of course to raise the Maxthreads to 400 we were pretty lucky that we already had a good dedicated Linux machine where the application was hosted (16GB Ram, 2 CPUs x 2.67 Ghz), thus raising MaxThreads to 400 was not such a big deal.

Here is the final config we used to fix tomcat timeouts:
 

<Connector port="11010" address="10.10.10.80" protocol="AJP/1.3" redirectPort="8443" MaxThreads="400" connectionTimeout="300000" keepAliveTimeout="300000" debug="9" />


One note to make here is the debug="9" options to Connector directive was used to increase debug loglevel of Tomcat, and address="" is the local network IP on which Tomcat instance runs. As you see, we choose to use very high connectionTimeouts (because it is crucial, not to cut requests to applications due to timeouts) in case of application slowness.

We also suspected that there are some Oracle (ORA) database queries slowly served on the SQL backend, that might in future cause more app slowness, but this has to be checked seperately further in time as presently we were checking we did not have our Db person present.

 

How to pass ITIL preparation – Dumps, PC and Mobile Android software to prepare

Wednesday, April 30th, 2014

Reading Time: 2minutes

ITIL-service-design-serice-operations-service-transition
I'm just coming from my ITIL (Information Technology Infrastructure Library) Foundations Exam. ITIL Certification is mandatory for all HP employees and everybody in my team already passed it. Thanks God I passed the ITIL as well with 87.5%.

To prepare for the exam I used Dump files (files with questions and answers given to people on previous exams) and software that simulates testing Avanset Visual CertExam Manager on PC as well as VCE Exam Simulator for Mobile.

VCE Exam Simulator is a test engine designed specifically for certification exam preparation. It allows you to create, edit, and take practice tests in an environment very similar to an actual exam.

ITIL exam was held here in Sofia in Technologica EAD Study Center. ITIL exam is kindly paid by HP and costs $250. ITIL Foundation is first level of certification next one is ITIL intermediate.

In order to prepare for ITIL it took me about half a day reading the ITIL Dump files (you can download them here) and 2 days of actively simulating the exams mainly with VCE EXam Simulator on my Android based mobile.
For those who want to become ITIL professionals and are going to certify further in ITIL Intermediate I recommend check all the ITIL Books covering the ITIL v.3 exam (here).

If you have the time and you want to have in depth understanding on ITIL also download and watch this ITIL Exam preparation Videos.

Here are also ITIL Foundation v.3 Dumps for Visual Cert exam manager. By the way ITIL exam is nowadays is required for almost anyone employeed in middle or large sized IT companies so if you still don't know anything about it and you're working or you will be working in the IT field take a look at. Lastly when I was looking for job offers I've noticed there are already plenty of companies who either require the candidate to have an ITIL passed or count ITIL certified candidates advantageous.

Automatic restart Tomcat on Windows script via TaskScheduler daily – A command line to add / remove new Windows “Cron” like job

Thursday, January 22nd, 2015

Reading Time: 4minutes

automatic-restart-Tomcat-on-Windows-via-TaskShcheduler-daily-weekly-monthly-a-command-line-to-add-remove-new-windows-cron-job
I'm responsbile for a project environment made up of 3 components which is occasionally dying. Here is a short raw overview of environment

  • Apache Reverse Proxy (entry door to app server)
  • Tomcat Server with an Application enabling web access
  • A Java Standalone application using SQLite database

 The Tomcat and Java Standalone application is running on top of Windows 2008 RC2 Standard, the overall environment is becoming inacessible periodically and in order to solve that the customer decided to implement a daily Windows server reboot in my opinion this is very bad approach as it is much better to just set an auto reboot of each of components using few tiny batch scripts and Windows Taskmgr, however as the customer is king and decided to implement the reboot its their own thing. 
However even fter the daily server reboot was set once a week or so the application was becoming inaccessible and a Tomcat server restart was necessery as a fix.

Finally as a work-around to the issue, I've proposed the logical thing to automatically restart Tomcat once a day early in morning, here is how Tomcat auto Restart was implemented on the Win server:

1. Check out the name of running Tomcat service

First thing is to use the sc command to find out the Tomcat application name:

 

how-to-show-tomcat-service-name-command-windows-screenshot

C:UsersGeorgi>sc query state= all| findstr "Tomcat"
SERVICE_NAME: Tomcat7_r2c
DISPLAY_NAME: Apache Tomcat Tomcat7_r2c

C:UsersGeorgi>

 

2. Create bat script to stop and start Tomcat service

Press keyboard Win-button + R, start notepad type inside:
 

@echo off
sc stop Tomcat7_r2c && sc start Tomcat7_r2c

(MyApp-Tomact-Restart-bat-file-ms-windows-screenshot

Don't be confused from screenshot that I have Tomcat7_MyApp instead of Tomcat7_r2c, but I made screenshot in hurry for another app.
Save the file, somewhere (preferrably) in application folder/bin/  it is best to save it once with bat extension MyApp-Tomcat_Restart.bat and once as MyApp-Tomcat_Restart.xml (XML format file is later needed for import to Task Scheduler which understands .XMLs). The .bat file is good to have because it is useful to somtimes restart Tomcat manually by running it (in case of some sudden Tomcat Appserver occurs even though the auto-restart script).
 

3. Create new Task using command line (cmd.exe)


Task can be created also from command line using following syntax:
 

schtasks /Create [/S [/U [/P [  ]]]]
/XML <xmlfile> /TN <taskname>

Simple way to create a new Windows task is shown in below command, it will set my Tomcat Restart script to run everyday in 05:00 early morning when no employees are using the system:

schTasks /Create /SC DAILY /TN "My Task" /TR "C:UsersGeorgiDesktopmyApp-Tomcat_Restart.bat" /ST 05:00
SUCCESS: The scheduled task "Tomcat Restart Task" has successfully been created.

 

import-new-windows-task-scheduler-task-from-command-line-windows-add-new-cronjob-command-screenshot


4. Create / Import new Windows "Cron" job 

Alternative way is to use Task Scheduler GUI frontend and create new (Basic Task) or  import just created script

To run Windows Task Scheduler from comamnd line :
 

Taskschd.msc

taskschd_windows-run-from-command-line-screenshot

To import already existing .XML formatted file for Task scheduler, right click on the Task Scheduler (Local) and select Import task

task-scheduler-local-task-import-microsoft-2008-r2-windows-screenshot

Import the myApp-Tomcat_Restart.XML previously created file

task-scheduler-import-tomcat-restart-xml-file-windows-server-2008-r2-screenshot

Adjust settings to suit your needs, but what change atleast:

  •         the path to the myApp-Tomcat_Restart.bat file in Actions tab
  •         the Local User account with which script will be running (administrator) in General tab

Task-Scheduler-windows-general-local-user-account-with-which-task-will-be-running

After making all changes you will be prompted for server Administrator account password 

5. check existing Win Cron job from command line

To see the configured (Scheduled Tasks) in command line mode with a command:

Schtasks.exe

schtasks-windows-equivalent-command-to-linux-unix-crontab-screenshot

The command is Windows equivalent to UNIX / Linux's crontab, e.g.:

crontab -u root -l


6. Delete existing Windows Task Job from Command line

If you happen to need to delete just created task or any other task from command line (Assuming that you know the previously created task name), use cmd:

C:>schtasks /Delete /TN "Tomcat Restart Task"
WARNING: Are you sure you want to remove the task "Tomcat Restart Task" (Y/N)? y

SUCCESS: The scheduled task "Tomcat Restart Task" was successfully deleted.


Task completed, Tomcat will auto-restart on Windows host at your scheduled time. Feedback is mostly welcome 🙂
Enjoy  

 

GNOME Desktop environment turns 15 – Happy Birthday GNOME :)

Saturday, August 18th, 2012

Reading Time: < 1minuteHappy 15 birthday to GNOME project

On 15 August one day before Debian Linux birthday and Debian manifesto announcement another important project for free software realm came to existence. On 15 Aug 1997 Miguel de Icaza, posted announcement explaining the major goals of the GNOME – GNOME Desktop project
The original announcement of GNOME Desktop Project can be read here
Last year GNOME has went through severe ups and downs, it was criticized and decredited by many of the true “believers” in the project because of the drastic turn the project does. Lest the ups and down, GNOME project is one of the most succesful free software project and in my view the most succesful FOSS software GUI.

Its interesting fact two major free software projects celebrate birthdays with 1 day difference. This makes August a major month for free softwar 🙂 As a long term Debian and GNOME user I felt obliged to drop few lines in thanks and congrats to GNOME which powers my desktop for 8 years already.

Happy Birthday GNOME! Happy Free Software month ! 🙂
Debian and GNOME happy birthday anniversary

How to install GNOME server on Ubuntu 10.04.2 LTS Lucid

Wednesday, April 20th, 2011

Reading Time: < 1minute
After some upgrades of Ubuntu from 9.10 to Ubuntu 10.04.2, I faced problems during apt-get upgrade && apt-get dist-upgrade

I had to fix it up with apt-get upgrade -f , however the “fix” which was targetting a fix up to the apt-get dist-upgrade removed about 260 packages, among which were the grub boot loader , xorg-server and even gnome

As in order to fix the package mishap the apt-get update -f was my only possible solution I went by and confirmed that I would like to wipe out all the packages.

Logically afterwards it was required that I install my missing xorg-server and gnome in order to make the Ubuntu desktop work again.

Here is how:

ubuntu:~# apt-get update && apt-get xorg-server ubuntu-desktop

The ubuntu-desktop is a meta package which installs the GNOME environment.

How to set applications (programs) Autorun on XFCE in Xubuntu Linux

Monday, January 16th, 2012

Reading Time: < 1minute

I needed to set TeamViewer to autorun, each and every startup on one Xubuntu Linux

Xubuntu is running by default with Xfce 4 . Xfce is a sort of a very liteweight GNOME like graphical environment.

In Gnome the way that is through invoking the gnome-session-manager .

In Xfce the command is almost analogous doing changes is done by running:

user@xubuntu:~$ xfce4-session-manager

XFce session manager Xubuntu Linux screenshot
Further on simply use the Add button to add applications to load each time user (opens xfce session) / logs in.
Cheers 😉

How to mount /proc and /dev and in chroot on Linux

Wednesday, April 20th, 2011

Reading Time: < 1minute
I’m using a backtrack Linux to recover a broken Ubuntu Linux, to fix this disastrous situation I’m using the Ubuntu Linux through chroot after mounting my /dev/sda1, where my Linux resides with:

linux-recovery:~# mkdir /mnt/test1
linux-recovery:~# mount /dev/sda1 /mnt/test1
linux-recovery:~# chroot /mnt/test1
ubuntu:~#

I consequently needed to mount up the /proc and /dev partition inside the chroot environment.

Here is how I did it:

ubuntu:~# mount /proc
ubuntu:~# mount -a

Next I switched on on a different virtual console in the backtrack and to mount /dev issued the commands:

linux-recovery:~# mount --bind /dev /mnt/test1/dev

Now once again, I can use theapt-get inside the chroot to fix up the whole mess …