Archive for April, 2010

Make your own Sundial

Thursday, April 8th, 2010

I have been always an amateur sciencist person, I like a lot Carl Sagan, astronomy, maths and computers. One devices that fascinated me a lot are sundials, I have combined it with my computer knowledge, and this is my contribution to the 2.0 sundial technology. 🙂 This post explain what I have done 🙂

I have designed is about paper sundials, sundials are tools that tells you the time, only with the shadow of the sun, to design a sundial you need to know exactly, where are you going to put it, you need to know the longitude, the latitude and the orientation of the wall with respect to North.
I have designed a web page, integrated with Google Maps, that helps you to find easily all the parameters needed, and finally produce a printable page, with a sundial paper cut, that can be cut and folded and give you a vertical Sundial.
This page allows you to make your own Cut Out Paper Vertical Sundial customized to your place on earth and the declination of the wall you are going to put it.

You will obtain a paper sundial like this:

paper sundial

the webpage gives you a printabel PDF, that you only need to cut and fold, this is a sample:

paper sundial

You can enjoy my webpage on: PAPER SUNDIALS

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How to install samba on voyage Linux

Sunday, April 4th, 2010

On this post I will explain howto install samba on Voyage Linux 0.5 version. Voyage Linux is the distribution I have installed on the minimotherboard Alix.

As you should know the systme doesn’t use a hard disk, It uses a Compact Flash memory card, that makes the hard disk functionality, I have a 8Gb compact Flash memory card where I have all teh space that I need.

the main disavantage of Compact Flash media, is that they are not writable every times you need, They have a nunmber of times you can rewrite, this number is high, between 300 thousand to million, that is the reason taht all the system, the voyage Linux distribution, is mounted read-only. you have two scripts, “remountrw”, to mount the filesystem with write permissions, and “remountro” to remount read only.
Moreover we have to take this into account on all the applications that need to write on disk.


RAM writable directories

Due that a lot of apps need to write in order to run, Voyage Linux, have a memory mounted partition where you can write, that is space is small (memory space), and is not permanent, you lost it where the system is rebooted.
The trick is that exists a directory called /ro where is all the information that will be copied to teh volatile directory on boot-time, the script taht makes that copy is on /etc/init.d/mountall the last line makes the copy using tar , tar -C /ro -cf - . | tar -C /rw -xf - > /dev/null 2>&1

And then when you need a writable directory yo make a link to the /rw directory, we can see an example with the var directory.


/var# ls -l
total 28
drwxr-xr-x 2 root root 4096 Jul 3 06:25 backups
drwxr-xr-x 6 root root 4096 Jun 26 16:34 cache
drwxr-xr-x 2 root root 4096 Jun 26 23:20 ccxstream
drwxr-xr-x 14 root root 4096 Jun 28 18:57 lib
drwxrwsr-x 2 root staff 4096 Oct 28 2006 local
lrwxrwxrwx 1 root root 12 Apr 15 00:28 lock -> /rw/var/lock
lrwxrwxrwx 1 root root 11 Apr 15 00:28 log -> /rw/var/log
lrwxrwxrwx 1 root root 12 Apr 15 00:28 mail -> /rw/var/mail
drwxr-xr-x 2 root root 4096 Feb 17 01:22 opt
lrwxrwxrwx 1 root root 11 Apr 15 00:28 run -> /rw/var/run
lrwxrwxrwx 1 root root 13 Apr 15 00:28 spool -> /rw/var/spool
lrwxrwxrwx 1 root root 11 Apr 15 00:28 tmp -> /rw/var/tmp
drwxr-xr-x 3 root root 4096 Jun 30 23:27 www

howo to install Samba

One interesting function our embedded is file sharing, we can share flash contents and contects mounted on usb ports.

This are the way to have it working:


#remountrw
#apt-get install samba
#remountro

since this point, It would be a normal samba installation on Debian, but if you try to boot samba it complans about file write permissions on the files located on /var/lib/samba, however samba works perfectly with remountrw, moreover we have to “convert” that files in writable ones.

INSTRUCCTIONS to make a writeble directory and make Samba works.

0.- We enable write permission ans install samba
#remountrw
apt-get install samba

1.- Copy the directory /var/lib/samba to /ro/var/lib/samba
tar -C /var/lib/samba -cf - . | tar -C /ro/var/lib/samba -xf -
2.- create a symbolic link from /rw/var/lib/samba to /var/lib/samba

mv /var/lib/samba /var/lib/samba.ori
ln -s /rw/var/lib/samba a /var/lib/samba

3.- Create a script to rewrite the files in case we made a modification we want persistent.

echo "tar -C /rw/var/lib/samba -cf - . | tar -C /ro/var/lib/samba -xf -" >/usr/local/bin/recopysambafiles
chmod +x /usr/local/bin/recopysambafile

4.- Reboot the server
reboot
5.-User creation

adduser nasuser
smbpasswd -a nasuser
remountrw
/usr/local/bin/recopysambafile
remountro
/etc/init.d/samba restart

We can check, It should work!! 🙂 The user could imagine with that example how to make work other apps like emule.

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Debian running on Netgear Stora

Thursday, April 1st, 2010

debian on netgear stora

As I explain on previous posts, I adquired a cheap two SATA bays home NAS, called Netgear Stora. After the disappointing privacy a features unfunctionalities the manufacturer give to us, the community again have achieved to develop an alternative way to open and use the software for this device, It is now achieved!! you can run an standard ARM Linux distribution on it!!

The hardware have:
-2 SATA bays.
-1 GB ethernet port
-1USB port
-ARM CPU
Processor : ARM926EJ-S rev 1 (v5l)
BogoMIPS : 992.87

-128Mb of RAM
-220Mb of flash Storage
-ventilator
-LEDs power, disk1, disk2

On my case, I have installed a flavor of Debian called emdebian.
emdebian

I have installed emdebian distribution on flash disk, but if you prefer, you could install a standard ARM Debian distribution using the hard disk.

It is a fantastic hardware to have a home Debian server.

If you are interested on this machine there is an active community on: http://hardwarehackersunite.com/.

The how to instruction are here: Howo to install Debian on Netgear Stora

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