HB blog

In addition to be annoying and time consuming some of telemarketers are real crooks. According to fraud.org here are six signs to recognise fraudent telemarketer and best action is to say thank you and hang up.

• Demanding that you act immediately or else miss out on this great opportunity….
• Promising that you can win money, make money, or borrow money easily…
• Refusing to send written information prior to your purchase or donation
• Trying to scare you into buying something
• Insisting you wire money or a courier will come by to pick up your payment
• Refusing to stop calling after you ask them to stop.

If you recognize one of those signs better say “NO, THANK YOU” and hangup.

Google is adding more apps to his Linux repository.

They also have script to setup repositories, but unfortunately it does not recognize CentOS and yum enabled distribution. I’ve added this code to check if yum is installed:

# Check if yum is installed RHEL v5 and CentOS 4.x and 5
if [ '/bin/rpm -q yum' ]; then
PACKAGEMANAGER=yum

Resulting script is here:

Google repos for centos

NOTE: After downloading the file just rename it from .txt to .sh and run with the shell:

bash google-repo-setup_CentOS.sh

Currently you can find there only picasa and google desktop

Here is a tutorial how to bring some of the Vista look  into XP.

This tutorial is for mouse cursors.

Thanks Alan.

Since a lot of people work in runlevel 3 the previous tip may not work.

So I’ve searched for other solutions found another way of disabling system beep (on tab completion).

Just edit /etc/inputrc

vi /etc/inputrc

and uncomment following line:

# do not bell on tab-completion
set bell-style none

Then after next login system beep on tab completion will be disabled system-wide.

And another one:

as root type:

rmmod pcspkr

This one will remove the module responsible for playing sound on system speaker.

Adding

blacklist pcspkr
in /etc/modprobe.d/blacklist

Should disable the module too, but it is not working for me under CentOS 5 - submitted as bug.

Another one (Hardware):

If you have PC simply open the case and unplug speaker cable from the motherboard.

NOTE: PC speaker could be very usefull when troubleshooting problems so this option is not really recommended.

OR search in your BIOS for option to disable it.

Part I

What is that?

Oracle XE - “Oracle Database 10g Express Edition (Oracle Database XE) is an entry-level, small-footprint database based on the Oracle Database 10g Release 2 code base that’s free to develop, deploy, and distribute; fast to download; and simple to administer….”

RHEL - is Linux for enterprise environment.

CentOS - “is an Enterprise-class Linux Distribution derived from sources freely provided to the public by a prominent North American Enterprise Linux vendor.” Aiming for binary compatibility with RHEL.

After first month of releasing CentOS 5.0 one of the questions was will Oracle and RHEL continue to work together and certify their products after release of Oracle Unbreakable Linux -based on RHEL.
Recently Redhat added Oracle Database 10gR2 to their software catalog, but in the meantime Oracle released Oracle Database 11g.

Enough theory let’s start.

First you need to download Oracle XE. I prefer(and recommend) using universal edition.

Then it becomes much simpler.

Just issue(from terminal):

rpm -ivh <path to oracle rpm>

In case of missing packages see my previous post for a way to install them.

After successful installation the installer instruct you to run:
/etc/init.d/oracle-xe configure

for initial configuration. Read carefully the questions and remember system password.

Then you are ready to use XE.

Just start the browser and type:

http://localhost:8080/apex

If you are not familiar with Oracle there are step by step instructions here and here, and official documentation here.

Troubleshooting:

If you cannot access web server after successful installation check your host name it seems that oracle xe do not likes FQDN hostname. In case that you do not have DNS server enter your FQDN in local hosts file.

Credits for the tip goes to Emerson.

Often when installing 3-d party software in RHEL/CentOS or other yum capable Linux OS there is a message of missing libraries or packages.

How to fix it?

Here is the trick.

You can use yum package manager to search for missing pieces.

yum whatprovides <package name/library>

This command will search all configured repositories for package that provides it.
Another option is to search Internet.

TIP: For better stability install only packages in official repositories. OR ones that clearly specify that they work on your OS/version.

Sometimes in troubleshooting process is necessary to turn of firewall for a short period of time.

In Linux based OS usually IPtables is used as firewall. It runs as service and could be stopped, started or restarted. In addition the status could be checked.

Here is how to do it:

Command line

When in terminal type:

/etc/init.d/iptables
Usage: /etc/init.d/iptables {start|stop|restart|condrestart|status|panic|save}

Gives you hints how to use it.

Note that to execute any of actions you need administrative privileges - either login as root, “su -” or setup sudo.

another tool that is doing the same is

service iptables <command>

If you like GUI but use command prompt you can use:

system-config-securitylevel-tui

And you will have simple interface of configuring security - firewall and selinux

GUI based

From GUI you can use the same tool just by removing -tui or go to System–>Administration –> Security level and firewall.

Another GUI frienly way is System–>Administration –> Services where you can do the same actions as from terminal.

TIP: Do not leave your system unprotected on Internet. Use cheap SOHO firewall in front of the system until IPtables is set up.

TIP: If you are newbie in firewall configuration use some third party tools as firestarter to guide you in your setup.

NOTE: Above steps are for RHEL (CentOS) compatible systems.

Manual White balance

This feature is present in most high end or “semiprofessional” cameras.

What it does?

Actually you can see it by yourself. Just take a white page and look at it in different lighting. When it is under sunlight it will appear white; Under low light it will appear gray; Under fluorescent lighting - purple … etc.

When digital camera is taking pictures all colors will be shifted and it will be really hard to obtain right colors. Manual white balance comes in help - when you use it point to something that you need to be white and camera will do the corrections for you.

In most of the cameras you have some preset values, but in real live this may not be enough.

Beginner photographs can ignore this feature.

Battery run time

One of important characteristics is how much time camera works on given set of batteries? Does it accept rechargeable batteries or already incorporates an integrated accumulator?

In later case you will need some additional information as:

• can you charge it in car or you will need to buy optional car charger? - If no you may need to consider buying DC to AC adapter.
• How much take for the accumulator to charge?
• What is the life of integrated accumulators? - usually measured in discharge/charge times

Tip: If you need to increase run time consider turning off LCD display. Of course you will need an optical viewer to see what you photograph. Unfortunately most of low cost cameras either do not have one or it “lies” - does not show correct picture area.

Attention: For some of the cameras out on the market the specifications show the time with optional high capacity accumulator and LCD turned off - read the fine-print.

Storage

One of important features is what type of storage is used into camera? What is maximum capacity? The recording speed?

Currently several technologies are used in digital cameras:

• CF - compact flash
• Micro-drive - miniature hard drive in CF format
• SD/MMC - secure digital/multimedia card
• MS - memory stick
• SM - smart media
• xD - picture card

They vary in sizes, speed and capacity and are often incompatible. So if your camera uses one you cannot put another format. Some of professional grade cameras are equipped with multiple slots supporting more than one type of card.

After determining the type you can shop for card prices and capacity. Verify camera documentation for maximum supported capacity.

Attention: Some cameras have small amount of integrated memory often impossible to expand.

Every camera has internal memory with capacity enough to store one picture and after you toke the picture the camera cannot take another one until the previous one is stored in storage media. So you need to verify the time need and how many pictures your camera can take before internal memory is filled.

To be continued

Now more about “other” specifications for a Digital Camera.

Angle of view

When photographing a group of people sometimes you need to take them closer together or step back to put all of them in a photo. This is called angle of view it depends on the ratio between the focal length and the film size.

As 35 mm cameras were professional standard, lenses are often described in terms of their “35 mm equivalent” fields of view. This is the difference between a normal lens (e.g. 50 mm), wide-angle lens (e.g. 24 mm), and telephoto lens (e.g. 500 mm). And is particularly common for digital cameras.

Mean values are 30-90mm for 3x zoom cameras.

Noise

The noise in the picture is one of most important parameters, but usually the one than is often omitted in characteristics of the camera.

Probably you’ve already seen that on some solid color areas you have dots or lines with different color just like when watching bad videotape on old VCR. This is called “noise”.

Theoretically if camera matrix is bigger there is less noise, but the size is not the only factor, the others like technology, thermal processes even electricity consumption are in play. So the best way of seeing the quality is to make test pictures. As a guide you can use camera sensitivity - usually measured in ISO. Camera with 50 ISO will be not so good as one with 800 ISO. In addition some professional cameras have noise reduction system.

Optic

The optic is one of the most important components for a camera. Low quality optic is usually seen when you take pictures with contrasting areas at the edge you could see colorful areas.

The only way to verify is to take test pictures.

Autofocus precision and speed

The precision and speed of autofocus differ from old 35mm cameras. On new digital cameras autofocus could take a second which could be crucial if you are going to take a picture of moving object, but is OK when taking static pictures. In addition autofocus could work properly when you have good lighting(such as taking picture outside), but poorly in low light (like taking picture at home).

Some cameras have low light indication and that is very useful, because in those conditions shutter is in 1/30 s and you need to keep camera steady - not a problem when light is good and shutter is 1/100 s.

to be continued…

How to create coloring page for your kids from photos from your archive.

This howto uses GIMP because it is freely available and do not requires that you buy more software.

For similar guide using photoshop see here.

Note: The picture for this example is taken from here.

What you will need:

• GIMP - can be downloaded for different paltforms for free.
• Initial image:

  

• Some creativity
• Printer
• Pencils

First install GIMP.

Then open the image

If needed adjust/crop the image.

Go to Filters–>Artistic–>Photocopy and change the paramethers until you are satisfied.

The result will look like this:

Next step will be to print the image on paper.

Finally use the creativity and pencils to color it.

Have fun….