Linux Administration Notes & Code Snippets

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linuxconfig — Sat, 03 Jul 2010 03:17:49 +0000

Get FREE complimentary Linux Guides
	The GNU/Linux Advanced Administration The GNU/Linux systems have reached an important level of maturity, allowing to integrate them in almost any kind of work environment, from a desktop PC to the sever facilities of a big company. In this ebook “The GNU/Linux Operating System”, the main contents are related with system administration. You will learn how to install and configure several computer services, and how to optimize and synchronize the resources using GNU/Linux. The topics covered in this 500+ page eBook include Linux network, server and data administration, Linux kernel, security, clustering, configuration, tuning, optimization, migration and coexistence with non-Linux systems. A must read for any serious Linux system admin.
	A Newbie’s Getting Started Guide to Linux Learn the basics of the Linux operating systems. Get to know what it is all about, and familiarize yourself with the practical side. Basically, if you’re a complete Linux newbie and looking for a quick and easy guide to get you started this is it. You’ve probably heard about Linux, the free, open-source operating system that’s been pushing up against Microsoft. It’s way cheaper, faster, safer, and has a far bigger active community than Windows, so why aren’t you on it? Don’t worry, Makeuseof.com understands. Like many things, venturing off into a completely unknown world can seem rather scary, and also be pretty difficult in the beginning. It’s while adapting to the unknown, that one needs a guiding, and caring hand. This guide will tell you all you need to know in 20 illustrated pages, helping you to take your first steps. Let your curiosity take you hostage and start discovering Linux today, with this manual as your guide! Don’t let Makeuseof.com keep you any longer, and download the Newbie’s Initiation to Linux. With this free guide you will also receive daily updates on new cool websites and programs in your email for free courtesy of MakeUseOf.
	A Complete Beginner’s Manual for Ubuntu 10.04 (Lucid Lynx) Getting Started with Ubuntu 10.04 (Lucid Lynx) is a comprehensive beginners guide for the Ubuntu operating system; it features comprehensive guides, How Tos and information on anything you need to know after first installing Ubuntu. Designed to be as user-friendly and easy to follow as possible, it should provide the first point of reference to any Ubuntu newcomer with lots of information. The manual has step by step instructions and includes lots of screenshots to show you how to do tasks. It also includes a Troubleshooting section to help you solve common Ubuntu problems quickly. Download this 160+ page manual today.

Filed under: Administration, apache, Bash, C, Cisco CCNA Preparation, Commands, Computer Vision, Database, Debian, Ebooks, Fedora, Fun and Linux, Games, GNOME, Google Search, joomla, KDE, Linux, Linux Programming Tutorial, N2100, Networks, OpenCV, Perl, Printing, Programming, Scripting, Security, SuSe, Ubuntu, Uncategorized, vmware, Web, XML

Turn Off directory browsing on Apache

linuxconfig — Sun, 28 Feb 2010 18:43:55 +0000

If your apache is chowing a indexes when browsing /var/www directory tree it might be considered as a security weakness. Unless you need your users to browse entire directory tree you may need to change a default apache setting in /etc/apache2/sites-available/yousite :

FROM:

Options Indexes FollowSymLinks MultiViews ExecCGI
AllowOverride None
Order allow,deny
allow from all

TO:

Options -Indexes FollowSymLinks MultiViews ExecCGI
AllowOverride None
Order allow,deny
allow from all

Filed under: Administration, apache

START and STOP rtorrent during peak and off-peak hour on thecus N2100

linuxconfig — Sun, 30 Aug 2009 00:38:06 +0000

I know that there is a syntax in a rtorrent config file to schedule throttle for uploads and download for rtorrent. However, no matter how hard I tried I did not work for my N2100 NAS device. The only value in regards to throttle uploads and downloads I can control is a global download_rate and upload_rate variable. So I came with a simple hack to use a crontab to stop , change config and start rtorrent. I have created two config files: one for offpeak and another for peak time. Once done edited a cron tast with
crontab -e
and add these lines:

00 7 * * * /raid/module/cfg/module.rc/RTORRENT.rc stop 01 7 * * * cp /root/rtorrent.rc_peak /raid/module/RTORRENT/system/etc/rtorrent.rc 02 7 * * * /raid/module/cfg/module.rc/RTORRENT.rc start

57 0 * * * /raid/module/cfg/module.rc/RTORRENT.rc stop 58 0 * * * cp /root/rtorrent.rc_offpeak /raid/module/RTORRENT/system/etc/rtorrent.rc 59 0 * * * /raid/module/cfg/module.rc/RTORRENT.rc start

Posted in Administration, Fun and Linux, N2100

Computer ebooks FTP download Links

linuxconfig — Wed, 26 Aug 2009 22:07:58 +0000

Some FTP links to download computer related ebooks. One may use:
wget -r URL
to download them all at once.

http://gog.gateit.net/books/

http://sodaphish.com/files/ebks/try2innovate.com/downloads/E-books/

http://orion.vratza.org/Books/Perl/?C=N%3BO=D

http://download.matus.in/doc/eBooks/

http://eduunix.ccut.edu.cn/index2/pdf/

http://www.dgi.gr/books/

http://www.superlinux.net/ebooks/

http://ftp.akaedu.org/mirror/202.96.64.144/books/

http://www.shizzilation.com/books/EBOOKS/Collection%20Of%20Various%20Computer%20Related%20Books/

http://ftp.akaedu.org/mirror/194.44.214.3/e-books/

http://files.hostingmania.rs/How-to/

http://slav0nic.org.ua/static/books/python/

http://www.echofoxx.com/doc/Oreillyhacks/

http://www.sinred.com/downloads/

http://books.osteching.com/

http://www.teroristi.org/books/

http://blacknite.eu/ebooks/

http://hide.osiris.com.br/ebooks/

Posted in Ebooks

Saving an output of PostgreSQL query to a text file

linuxconfig — Fri, 14 Aug 2009 23:53:09 +0000

In PostgreSQL database it is possible to save / export and results of a database query to a simple text file. By default all query result are displayed on the screen. This default behavior can be overwritten by \o command:

postresql=> \o /path/to/your/text/file.txt postresql=> postgresql query ( here place your query ) postresql=> \o ( set back the default output behavior )

Posted in Database, Linux

VMware arrow keys problem on Ubuntu

linuxconfig — Thu, 13 Aug 2009 22:55:10 +0000

After power up my vmware virtual machines on the Ubuntu I have had a problems using arrow keys when my mouse pointer was captured by the console. Could no move at all and I had to use and Num pad on my keyboard to move around which was really annoying since I could not type a numbers because I had to keep my Num Lock OFF. The solution to this problem is simple:
echo 'xkeymap.nokeycodeMap = true' >> ~/.vmware/config

Posted in Administration, Linux, Uncategorized, vmware

101 howto start with opencv and computer vision on ubuntu linux

linuxconfig — Tue, 07 Jul 2009 00:16:46 +0000

Recently I was tempted to have a look on OpenCV project and Oreilly’s book “Learning OpenCV” This is a great book and it assumes some basic C programming skills. However, it is not specific to any platform when it comes to compiling and running program examples. Here is a very short start with Ubuntu 9.04

Let’s start with installation of some useful packages into our ubuntu system:

apt-get install libcv1 libcvaux1 libhighgui1 libcv-dev libcvaux-dev libhighgui-dev libavcodec-dev libavformat-dev libavutil-dev libavutil49 pkg-config g++

Once this is done we can start by compiling a first example in the book ( make sure that you have all quotes corect otherwise you will get errors like:
opencv.c:1:10: error: #include expects "FILENAME" or

actual example code:

#include "highgui.h"


int main(int argc, char** argv)

{

IplImage* img = cvLoadImage( argv[1] );

cvNamedWindow( "Example1", CV_WINDOW_AUTOSIZE );

cvShowImage( "Example1", img );

cvWaitKey(0);

cvReleaseImage( &img );

cvDestroyWindow( "Example1" );

exit(0); }

now it’s time to save this code into file. For example let us save it into myopencv.c file.

to compile this code we can use command:

g++ -ggdb -I/usr/include/opencv -lhighgui myopnecv.c.c -o opencv_example

another way to compile is to use pkg-config
g++ -ggdb `pkg-config opencv --cflags --libs` myopnecv.c.c -o opencv_example
which is exactly the same as
g++ -ggdb -I/usr/include/opencv -lcxcore -lcv -lhighgui -lcvaux -lml myopnecv.c.c -o opencv_example

the library must be included for compilation otherwise this errors would occur:
myopnecv.c:In function `main': myopnecv.c:(.text+0x25): undefined reference to `cvLoadImage' myopnecv.c:(.text+0x3c): undefined reference to `cvNamedWindow' myopnecv.c:(.text+0x4f): undefined reference to `cvShowImage' myopnecv.c:(.text+0x5b): undefined reference to `cvWaitKey' myopnecv.c:(.text+0x66): undefined reference to `cvReleaseImage' myopnecv.c:(.text+0x72): undefined reference to `cvDestroyWindow'

OR
error: too few arguments to function ‘cvLoadImage’

if your compilation was successful a opencv_example binary should appear in your directory. when running this binary supply an argument ( some picture ):

./opencv_example mypicture.jpg

the image should pop up on your screen.

Get FREE complimentary Linux Guides
	The GNU/Linux Advanced Administration The GNU/Linux systems have reached an important level of maturity, allowing to integrate them in almost any kind of work environment, from a desktop PC to the sever facilities of a big company. In this ebook “The GNU/Linux Operating System”, the main contents are related with system administration. You will learn how to install and configure several computer services, and how to optimize and synchronize the resources using GNU/Linux. The topics covered in this 500+ page eBook include Linux network, server and data administration, Linux kernel, security, clustering, configuration, tuning, optimization, migration and coexistence with non-Linux systems. A must read for any serious Linux system admin.
	A Newbie’s Getting Started Guide to Linux Learn the basics of the Linux operating systems. Get to know what it is all about, and familiarize yourself with the practical side. Basically, if you’re a complete Linux newbie and looking for a quick and easy guide to get you started this is it. You’ve probably heard about Linux, the free, open-source operating system that’s been pushing up against Microsoft. It’s way cheaper, faster, safer, and has a far bigger active community than Windows, so why aren’t you on it? Don’t worry, Makeuseof.com understands. Like many things, venturing off into a completely unknown world can seem rather scary, and also be pretty difficult in the beginning. It’s while adapting to the unknown, that one needs a guiding, and caring hand. This guide will tell you all you need to know in 20 illustrated pages, helping you to take your first steps. Let your curiosity take you hostage and start discovering Linux today, with this manual as your guide! Don’t let Makeuseof.com keep you any longer, and download the Newbie’s Initiation to Linux. With this free guide you will also receive daily updates on new cool websites and programs in your email for free courtesy of MakeUseOf.
	A Complete Beginner’s Manual for Ubuntu 10.04 (Lucid Lynx) Getting Started with Ubuntu 10.04 (Lucid Lynx) is a comprehensive beginners guide for the Ubuntu operating system; it features comprehensive guides, How Tos and information on anything you need to know after first installing Ubuntu. Designed to be as user-friendly and easy to follow as possible, it should provide the first point of reference to any Ubuntu newcomer with lots of information. The manual has step by step instructions and includes lots of screenshots to show you how to do tasks. It also includes a Troubleshooting section to help you solve common Ubuntu problems quickly. Download this 160+ page manual today.

Posted in C, Computer Vision, Linux, OpenCV, Programming

Setting up HP officejet – Ubuntu Linux Jaunty

linuxconfig — Wed, 06 May 2009 12:03:22 +0000

Here is a quick installation of HP officejet printer on Ubuntu linux jauntu:
# apt-get install hplib
Enable X-window to root
$ xhost +
# hp-setup
If the automatic discovery does not work tick a manual selection and enter IP address of your printer. If its USB go for USB option. All done.

Posted in Administration

Joomla – Error: the XML response that was returned from the server is invalid

linuxconfig — Fri, 01 May 2009 03:18:44 +0000

Today I have had a problem to install a Joomla 1.5 on my VPS server. In fact I was able to install it but without Sample Data. The error message that I was getting was:
Error: the XML response that was returned from the server is invalid

I took me hour to find the problem. If you come across this problem do not create a configuration.php script at the beginning of the installation even if the installer will complain about it.

Posted in Administration, joomla

Display google search results from different contries

linuxconfig — Sun, 26 Apr 2009 01:54:50 +0000

In many occasions I have tried to search for key words and get a results form a country which is not the one I’m searching from.

For example if I try to Google search from Australia and entering a a URL of google.com I’m automatically redirected to the google.com.au since my IP address reveals that my location is Australia. The trick is to pass a &gl= variable from the URL.

for example to get a United States results I will enter url:

http://www.google.com.au/webhp?hl=en&btnG=Google+Search&gl=us

United Kingdom:

http://www.google.com.au/webhp?hl=en&btnG=Google+Search&gl=uk

Sometimes it is easier to do:
http://www.google.co.uk/ however this does not work with google.com

Posted in Google Search