Algorithmic Madness

Lubuntu suggested installs

2011-12-29T02:13:00.000-08:00

I like LXDE, but there are some things in Gnome that I just can't live without.
So the proposed installs are:

sudo apt-get install gnome-terminal
sudo apt-get install alacarte (for the menu editor)

Lubuntu Custom Application Launcher

2011-12-20T02:03:00.001-08:00

Taken from http://linux.koolsolutions.com/2009/09/11/howto-place-programs-on-lxde-desktop/

Step 1: Create a text file

# nano README.TXT
Contents:

Hello, How are you today?

Save and exit.

Step 2: Create a corresponding .desktop file

Now we will create a corresponding .desktop file for the text file that we created in Step 1. Note that all the .desktop file will reside in the /usr/share/applications folder.

# cd /usr/share/applications/
# nano README.desktop

and type the following contents:

[Desktop Entry]
Encoding=UTF-8
Name= README
Comment= My README file
Exec=lxterminal --command "less /root/README.TXT"
Icon=/usr/share/pixmaps/readme.xpm
MimeType=text/plain
Terminal=false
Type=Application
MimeType=text/plain
Categories=Utility

Save and exit.

Let’s take a moment and understand what is going on in the above file:

Name - Give any name you want

Comment – Your own comment

Exec – Basically we are telling which program to use to open our text file. In this case we are opening the text file with “less” command in the lxterminal window. You could have also given the following:

Exec=leafpad /root/README.TXT

Icon – I copied my own icon, readme.xpm, in the “/usr/share/pixmaps” directory. You can do the same or just use the default icons that are available in that directory.

Rest all the fields should generally remain the same.

Step 3: Create a “Desktop” directory

Now we will create a directory called “Desktop” in the user’s home directory. So for example, if the user is “root”, then we will create the directory as follow:

# cd;
# mkdir Desktop

If your user is at “/home/kushalk”, then you would create the directory as follow:

# mkdir /home/kushalk/Desktop

Step 4: Link the .desktop file with Desktop folder

This is the last piece of puzzle which will bring everything together. Now all we need to do is to link the “.desktop” file created in Step 2 inside the “Desktop” directory created in Step 3.

# cd;
# cd Desktop
# ln -s /usr/share/applications/README.desktop .

That’s it. As soon as you give the above coomand, an icon should appear on your Desktop. In case if the icon still does not appear, simply logout from LXDE and log back in.

Happy LXDE’ing!

Lubuntu change keyboard layout

2011-12-16T16:15:00.000-08:00

sudo nano /etc/xdg/lxsession/Lubuntu/autostart

@setxkbmap -option grp:switch,grp:alt_shift_toggle,grp_led:scroll us,gr

Lubuntu autologin

2011-12-16T16:09:00.001-08:00

/etc/lxdm/default.conf

just uncomment to activate it & put your name.

Startup Script for Glassfish

2011-12-16T04:34:00.000-08:00

Write a script. put it in the /etc/init.d/ directory.
Lets say you called it FOO. You then run

% update-rc.d FOO defaults

chmod +x FOO

THE SCRIPT FOLLOWS:

export AS_JAVA=/usr/lib/jvm/java-6-sun

GLASSFISHPATH=/home/optitrans-server-testing/Programs/glassfish3/bin

case "$1" in

start)

echo "starting glassfish from $GLASSFISHPATH"

$GLASSFISHPATH/asadmin start-domain domain1

#we need to use this later when we enable https

#sudo -u glassfish $GLASSFISHPATH/asadmin --secure start-domain domain1

;;

restart)

0€ stop

0€ start

;;

stop)

echo "stopping glassfish from $GLASSFISHPATH"

$GLASSFISHPATH/asadmin stop-domain domain1

#we need to use this later when we enable https

#sudo -u glassfish $GLASSFISHPATH/asadmin --secure stop-domain domain1

;;

echo $"usage: 0€ {start|stop|restart}"

exit 3

;;

esac

How to change the MySQL data default directory

2011-11-25T01:45:00.001-08:00

Taken from http://www.ubuntugeek.com/how-to-change-the-mysql-data-default-directory.html

sudo /etc/init.d/mysql stop

sudo cp -R -p /var/lib/mysql /path/to/new/datadir

gksu gedit /etc/mysql/my.cnf

change the entry with datadir

sudo gedit /etc/apparmor.d/usr.sbin.mysqld

Copy the lines beginning with “/var/lib/mysql”, comment out the originals with hash marks (“#”), and paste the lines below the originals.

sudo /etc/init.d/apparmor reload

sudo /etc/init.d/mysql restart

Object to byte array and byte array to Object in Java

2011-10-21T03:31:00.000-07:00

Taken from http://scr4tchp4d.blogspot.com/2008/07/object-to-byte-array-and-byte-array-to.html

public byte[] toByteArray (Object obj)
{
byte[] bytes = null;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
try {
ObjectOutputStream oos = new ObjectOutputStream(bos);
oos.writeObject(obj);
oos.flush();
oos.close();
bos.close();
bytes = bos.toByteArray ();
}
catch (IOException ex) {
//TODO: Handle the exception
}
return bytes;
}

public Object toObject (byte[] bytes)
{
Object obj = null;
try {
ByteArrayInputStream bis = new ByteArrayInputStream (bytes);
ObjectInputStream ois = new ObjectInputStream (bis);
obj = ois.readObject();
}
catch (IOException ex) {
//TODO: Handle the exception
}
catch (ClassNotFoundException ex) {
//TODO: Handle the exception
}
return obj;
}

SSH without password

2011-07-19T05:21:00.000-07:00

Taken from http://linuxproblem.org/art_9.html

Your aim

login from host A / user a to Host B / user b.
call ssh from a within a shell script.

How to do it

First log in on A as user a and generate a pair of authentication keys. Do not enter a passphrase:

a@A:~> ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/a/.ssh/id_rsa):
Created directory '/home/a/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/a/.ssh/id_rsa.
Your public key has been saved in /home/a/.ssh/id_rsa.pub.
The key fingerprint is:
3e:4f:05:79:3a:9f:96:7c:3b:ad:e9:58:37:bc:37:e4 a@A
Now use ssh to create a directory ~/.ssh as user b on B. (The directory may already exist, which is fine):

a@A:~> ssh b@B mkdir -p .ssh
b@B's password:
Finally append a's new public key to b@B:.ssh/authorized_keys and enter b's password one last time:

a@A:~> cat .ssh/id_rsa.pub | ssh b@B 'cat >> .ssh/authorized_keys'
b@B's password:
From now on you can log into B as b from A as a without password:

a@A:~> ssh b@B hostname
B
A note from one of our readers: Depending on your version of SSH you might also have to do the following changes:

Put the public key in .ssh/authorized_keys2
Change the permissions of .ssh to 700
Change the permissions of .ssh/authorized_keys2 to 640

CLAPACK Installation in Netbeans,LINUX

2010-11-23T18:54:00.001-08:00

Just to save a couple of hours of sleep for some people like me.

1)Download clapack.tgz from http://www.netlib.org/clapack/

2)Extract and call "make" inside the main directory

3)Call the following in terminal:

cp lapack_LINUX.a liblapack_LINUX.a

cp blas_LINUX.a libblas_LINUX.a

ranlib libblas_LINUX.a

ranlib liblapack_LINUX.a

cd F2CLIBS/

cp libf2c.a liblibf2c.a

ranlib liblibf2c.a

cp liblibf2c.a ../

4)Create new C Project in Netbeans

5)Change the makefile to contain only this:

CC = gcc

ROOTPATH = /path/to/clapack

main:main.o

$(CC) -o ./dist/Debug/GNU-Linux-x86/NAME_OF_PROJECT/main.c -I$(ROOTPATH)/INCLUDE -L$(ROOTPATH) -llapack_LINUX -lblas_LINUX -llibf2c -lm

Very helpful topic:

http://icl.cs.utk.edu/lapack-forum/viewtopic.php?f=2&t=2020

Lyx : LaTeX Frontend

2010-09-01T09:35:00.001-07:00

GUI for writing in LaTeX

1) sudo apt-get install lyx

2) If you want to see your math symbols instead of red text, also install the latex-xft-fonts package.

3) latex2html allows lyx to produce html output.

4) foiltex is useful for making presentations.

5) After installing such packages you should reconfigure ( goto Edit -> Reconfigure) and then restart LyX.

For Greek support:

6) Install packages texlive-lang-greek,texlive-fonts-extra,texlive-latex-extra

GRUB2 tips

2010-07-31T06:53:00.003-07:00

In case something is f****d up with multiple partitions, multiple grubs etc.

1)Live Ubuntu CD startup

2)sudo fdisk -l

to check the right sda (in my case sda2)

3)sudo mount /dev/sda2 /mnt

sudo mount /dev/sda2 /mnt/boot

sudo mount --bind /dev /mnt/dev

sudo chroot /mnt

grub-install /dev/sda

4) Cntrl+D

5)sudo umount /mnt/dev

sudo umount /mnt

Blog Client for (K)Ubuntu

2010-07-31T06:25:00.001-07:00

Great program, with which the first post will be published!

It is called Biblo Blogger. Brief instructions. Yes terminal.

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com \ 0xfe0272d55c41c17774052e575646f8b10331274d

echo deb http://ppa.launchpad.net/neversfelde/ppa/ubuntu `lsb_release --short --codename` main | sudo tee -a /etc/apt/sources.list

sudo apt-get update ; sudo apt-get install bilbo

Blog--->Add Blog--->URL+username+password--->Auto Configure

For adding tags, Post Categories.

Credits to http://bigbrovar.wordpress.com/2009/09/06/the-ultimate-blogging-client-for-linux/