Toplink throws NullPointerException in method _toplink.getXXX_vh()

If you persist JPA entities from another JVM sometimes Toplink throws very strange exception like:

Caused by: javax.persistence.EntityExistsException: 
Exception Description: The method [_toplink_getscore_vh] on the object [com.mycompany.data.GameEntity] triggered an exception.
Internal Exception: java.lang.reflect.InvocationTargetException
Target Invocation Exception: java.lang.NullPointerException
Mapping: oracle.toplink.essentials.mappings.OneToOneMapping[score]
Descriptor: RelationalDescriptor(com.mycompany.data.GameEntity --> [DatabaseTable(GAME_TABLE)])
 at oracle.toplink.essentials.internal.ejb.cmp3.base.EntityManagerImpl.persist(EntityManagerImpl.java:224)
 at com.sun.enterprise.util.EntityManagerWrapper.persist(EntityManagerWrapper.java:440)
 at com.mycompany.MyEjbBean.create(MyEjbBean.java:1647)
 ... 26 more
Caused by: Exception [TOPLINK-99] (Oracle TopLink Essentials - 2.1 (Build b31g-fcs (10/19/2009))): oracle.toplink.essentials.exceptions.DescriptorException
Exception Description: The method [_toplink_getscore_vh] on the object [com.mycompany.data.GameEntity] triggered an exception.
Internal Exception: java.lang.reflect.InvocationTargetException
Target Invocation Exception: java.lang.NullPointerException
 at oracle.toplink.essentials.exceptions.DescriptorException.targetInvocationWhileGettingValueThruMethodAccessor(DescriptorException.java:1598)
 at oracle.toplink.essentials.internal.descriptors.MethodAttributeAccessor.getAttributeValueFromObject(MethodAttributeAccessor.java:98)
 at oracle.toplink.essentials.mappings.DatabaseMapping.getAttributeValueFromObject(DatabaseMapping.java:372)
 at oracle.toplink.essentials.mappings.ForeignReferenceMapping.getAttributeValueFromObject(ForeignReferenceMapping.java:322)
 at oracle.toplink.essentials.mappings.ObjectReferenceMapping.cascadeRegisterNewIfRequired(ObjectReferenceMapping.java:676)
 at oracle.toplink.essentials.internal.descriptors.ObjectBuilder.cascadeRegisterNewForCreate(ObjectBuilder.java:1294)
 at oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl.registerNewObjectForPersist(UnitOfWorkImpl.java:3228)
 at oracle.toplink.essentials.internal.ejb.cmp3.base.EntityManagerImpl.persist(EntityManagerImpl.java:221)
 ... 28 more
Caused by: java.lang.reflect.InvocationTargetException
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:597)
 at oracle.toplink.essentials.internal.security.PrivilegedAccessHelper.invokeMethod(PrivilegedAccessHelper.java:322)
 at oracle.toplink.essentials.internal.descriptors.MethodAttributeAccessor.getAttributeValueFromObject(MethodAttributeAccessor.java:91)
 ... 34 more
Caused by: java.lang.NullPointerException
 at com.mycompany.data.GameEntity._toplink_getscore_vh(GameEntity.java)
 ... 40 more
javax.ejb.EJBException: nested exception is: java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: 
 java.rmi.RemoteException: null; nested exception is: 
 java.lang.RuntimeException: 
 at com.mycompany._MyEjbBean_Wrapper.create(com/mycompany/_MyEjbBean_Wrapper.java)
 at com.mycompany.GameTest.testGameScores(GameTest.java:62)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 at java.lang.reflect.Method.invoke(Unknown Source)
 at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
 at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
 at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
 at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
 at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
 at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:73)
 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:46)
 at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:180)
 at org.junit.runners.ParentRunner.access$000(ParentRunner.java:41)
 at org.junit.runners.ParentRunner$1.evaluate(ParentRunner.java:173)
 at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
 at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
 at org.junit.runners.ParentRunner.run(ParentRunner.java:220)
 at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46)
 at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

The solution I found is to change the score property to be eager "@ManyToOne(fetch = FetchType.EAGER)" What I belive happens beneath is that Toplink uses bytecode to creates some additional methods for entity classes - see oracle.toplink.essentials.internal.weaving.TopLinkClassWeaver. For each field that is in relation, Toplink creates a new method called _toplink.getFIELDNAME_vh() and a class field called _toplink.getFIELDNAME_vh. VH stands for ValueHolder. I guess this additional methods/fields are used for fetching related objects later. If you examine the exception more closely it is thrown from inside _toplink.getscore_vh() which according to the javadoc in TopLinkClassWeaver should looks like:

public WeavedAttributeValueHolderInterface _toplink_getscore_vh(){
  if (_toplink_score_vh.isCoordinatedWithProperty() || _toplink_score_vh.isNewlyWeavedValueHolder()){
    EntityC object = getScore();
    if (object != _toplink_score_vh.getValue()){
      setScore(object);
    }
  }
  return _toplink_score_vh;
}

Obviously the only way to throw an exception is if _toplink_score_vh is null which after debuging is confirmed to be null. My guess is that because this is entity is transferred from another JVM (the JUnit test) and you are persisting it inside server JVM the value of _toplink_score_vh is not correctly transfered, which causes the above exception. I didn't dig up too much into the problem but the solution I found is - just make the field (in my case the "score") eager and the exception will go away.

Forget to add administrators group to SQL server 2008

Yep shit happens...
If you forget to add the administrator group (or at least the current user) to admin groups, and do not know the SA password then you have only two options
- reinstall SQL server
- use single-user-mode to add the accounts

Ok now the single-user-mode procedure.
0) login with Administrator (exactly the Administrator user, with another administrator account there will be problems)
1) open services.msc
2) go the "SQL Server (xxx)" service and stop it
3) open "Sql server configuration manager" from the start menu and make sure that the protocols "Shared memory", "Named pipes", "TCP/IP" are enabled
4) Go back to the services console right click "SQL Server (xxx)" and select properties and then enter "-m" as parameter. Click start
5) Now the server is started in single-user mode
6) Open command prompt and execute following command "sqlcmd -S \ -E", where -S specifies server and instance name, -E specifies to use windows credentials

sqlcmd -S MYMACHINE\SQLEXPRESS -E

7) Execute following commands for each windows account that you want to add

CREATE LOGIN [MYMACHINE\Administrator] FROM WINDOWS
GO
exec sp_addsrvrolemember @loginame='MYMACHINE\Administrator', @rolename = 'sysadmin' 
GO

8) Stop the SQL service and restart it without -m parameter.
9) Now you are able to log-in with Administrator user and you do have administrator rights on SQL server

Using older Java on Windows

When JDK 7 is installed it became the default java on the machine. However if you try to set different JDK (by JAVA_HOME and PATH variables) it won't change. The reason is that there is a c:\windows\system32\java.exe wrapper that reads the system registry and executes the java. If you try to change
HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment\CurrentVersion to 1.6 you will get the following error:

C:\Windows\System32>java -help
Error: Registry key 'Software\JavaSoft\Java Runtime Environment'\CurrentVersion'

has value '1.6', but '1.7' is required.
Error: could not find java.dll
Error: Could not find Java SE Runtime Environment.

I found two solutions on this problem:
1) use -version:1.6 as parameter

java -version:1.6 -jar myprogram.jar

It will run the jar with version 1.6
Of course you can set it into some system property like JAVA_OPT (for tomcat)

2) Add JAVA_HOME environment variable, and put %JAVA_HOME%\bin before %SystemRoot%\system32.
So the JAVA_HOME\bin\java.exe will be found before the c:\windows\system32\java.exe wrapper.

Java 7 - project coin

Java 7 language syntax changes in nutshell (Project coin).

• Strings in switch


• Binary integral literals and underscores in numeric literals


• Multi-catch and more precise rethrow


• Improved type inference for generic instance creation (diamond)


• try-with-resources statement


• Simplified varargs method invocation

Strings in switch

public static boolean getBoolean(String s) { 

   switch(s.toLowerCase()) { 

      case "true" : return true; 

      case "false" : return false; 

      default: throw new IllegalArgumentException("Invalid value. Only strings 'true' and 'false' are acceptable"); 

   } 

} 

Binary integral literals and underscores in numeric literals

public static final int binaryNumber = 0b11111111_11111111;// 65535

public static final int hexNumber = 0xFF_FF;// 65535

Multi-catch and more precise rethrow

Multi-catch

try {    

    Class<?> c = Class.forName("java.lang.String");

    Object o = c.newInstance();

    Method m = c.getMethod("length");

    System.out.println("Length = " + m.invoke(o));        

} catch (ClassNotFoundException | IllegalAccessException | InstantiationException 

         | InvocationTargetException | IllegalArgumentException | NoSuchMethodException ex ) {

   ex.printStackTrace();

}

ReflectiveOperationException

try {    

    Class<?> c = Class.forName("java.lang.String");

    Object o = c.newInstance();

    Method m = c.getMethod("length");

    System.out.println("Length = " + m.invoke(o));        

} catch (ReflectiveOperationException ex ) {

   // Now all reflection exception have super class ReflectiveOperationException

   ex.printStackTrace();

}

more precise rethrow

public static class Exception1 extends Exception {}

public static class Exception2 extends Exception {}

    

public void morePreciseExceptionRethrow() throws Exception1, Exception2 {

    try {

        if (1==2) {

            throw new Exception1();

        } else {

            throw new Exception2();

        }

    } catch (Exception ex) {

// here the compiler knows that only Exception1 and Exception2 are thrown from the code above. In JDK 1.6 you need to declare that the method is throwing Exception, but in JDK 1.7 you may declare only the exceptions really thrown.

        throw ex; 

    }

}

Improved type inference for generic instance creation (diamond)

List list = new ArrayList<>();

Map> map = new TreeMap<>();

try-with-resources statement

public void copy(String srcFileName, String destFileName) throws IOException {

   try(InputStream in = new FileInputStream(srcFileName); OutputStream out = new FileOutputStream(destFileName)){

      byte[] buff = new byte[1024];

      int n;

      while ((n = in.read(buff)) != -1) {

          out.write(buff, 0, n);

      }

   }

   // here the in and out are closed

}

Simplified varargs method invocation

More details

Creating GIT projects based on SVN dumps

Following script will create new GIT projects based on SVN dump files.
As prerequisite you must have setup Gerrit codereview system. You need to allow the Gerrit user to directly push to master branch, otherwise all SVN commits need to be reviewed/verified, and for existing project this could means hundreds of commits.

Script:

#!/bin/bash
#!/bin/bash
GERRIT_IP=10.1.1.1
GERRIT_USER=xxx
GERRIT_PORT=29418

if [ -z "$1" ]; then
echo "Provide SVN dump file as first argument"
exit -1
fi

if [ ! -f $1 ]; then
echo "SVN dump $1 doesn't exists"
exit -1
fi

if [ -z "$2" ]; then
echo "Provide project name (that will be created in GIT) as second argument"
exit -2
fi

if [ -e $2 ]; then
echo "File or directory with name $2 already exists"
exit -2
fi


CURR_DIR=`pwd`

rm -Rf svnrepo
svnadmin create svnrepo/

svnadmin load svnrepo/ < $1
git svn clone file://$CURR_DIR/svnrepo/ $2
ssh -p $GERRIT_PORT -l $GERRIT_USER $GERRIT_IP gerrit create-project --name $2

# add origin
echo -e "[remote \"origin\"]" >> $2/.git/config
echo -e "\tfetch = +refs/heads/*:refs/remotes/origin/*" >> $2/.git/config
echo -e "\turl = ssh://$GERRIT_USER@$GERRIT_IP:$GERRIT_PORT/$2" >> $2/.git/config
echo -e "\tpush = HEAD:refs/for/master" >> $2/.git/config

# add originmaster
echo -e "[remote \"originmaster\"]" >> $2/.git/config
echo -e "\tfetch = +refs/heads/*:refs/remotes/origin/*" >> $2/.git/config
echo -e "\turl = ssh://$GERRIT_USER@$GERRIT_IP:$GERRIT_PORT/$2" >> $2/.git/config
echo -e "\tpush = HEAD:refs/heads/master" >> $2/.git/config

# add master branch config
echo -e "[branch \"master\"]" >> $2/.git/config
echo -e "\tremote = originmaster" >> $2/.git/config
echo -e "\tmerge = refs/heads/master" >> $2/.git/config


cd $2
git push originmaster
cd ..

In nutshell The script creates a dummy SVN repository, then use git-svn command to create local git project, creates a new project in Gerrit, adds Gerrit as remote repository to the local GIT configuration and finally pushes the changes to Gerrit

In order to use the script you need to provide a SVN dump file as first argument, and GIT project name as second argument

Install Gerrit

1) Install tomcat.

2) Download/build gerrit.war to tomcat websapps directory

3) Create gerrit directory

mkdir /usr/share/gerrit

4) Initialize gerrit configurations

java -jar gerrit.war init -d /usr/share/gerrit

- Choose default values for all configuration except
- Choose authentication method HTTP
- Enter tomcat as "run-as user"
- Choose to Update/copy gerrit.war
- Choose to use Bouncy Castle

5) Edit /usr/share/gerrit/etc/gerrit.conf
and it modify it to looks like this:

[gerrit]
basePath = git
[database]
type = H2
database = db/ReviewDB
[auth]
type = LDAP
[sendemail]
smtpServer = localhost
[container]
user = tomcat
javaHome = /usr/lib/jvm/jdk1.6.0_26/jre
[sshd]
listenAddress = MYIP:8418
[httpd]
listenUrl = http://*:8282/
[cache]
directory = cache
[ldap]
server = ldap://MYIP:10389
username = uid=gerrit,ou=users,ou=system
password = gerrit
accountBase = ou=Users,dc=MYHOST
accountPattern = (&(objectClass=person)(uid=${username}))
accountFullName = displayName
accountEmailAddress = mail

groupBase = ou=Groups,dc=MYHOST
groupMemberPattern = (&(objectClass=groupOfUniqueNames)(uniquemember=${dn}))

Where you need to replace MYIP, MYHOST with the IP and the host name of the machine.
Note the LDAP configuration. We need to add gerrit user to ou=system and create the MYHOST domain structure.

6) Install ApacheDS LDAP server for user management. (There is a RPM package for Fedora, so just download and follow installation instructions).

7) We need to configure ApacheDS.
Open /var/lib/apacheds/default/conf/server.xml and add new partition

<jdbmPartition id="MYHOST" suffix="dc=MYHOST" optimizerEnabled="true" syncOnWrite="true" cacheSize="100"/gt;

Replace MYHOST with machine hostname.

Remove anonymous access

<defaultDirectoryService ... allowAnonymousAccess="false" ... >

7) Start the service

service apacheds start default

8) Install and Apache Directory Studio and connect to LDAP server

ldap://MYHOST:10389

where MYHOST is the hostname/IP address of the machine
The default username is "uid=admin,ou=system" and password is "secred"

Go to ou=system, and select uid=admin. Change the userPassword attribute with new password


9) Add new user to ApacheDS. Open Apache Directory Studio and import following LDIF

dn: uid=gerrit,ou=users,ou=system
objectClass: organizationalPerson
objectClass: person
objectClass: inetOrgPerson
objectClass: top
cn: gerrit administrator
sn: gerrit
displayName: Gerrit administrator
uid: gerrit
userPassword:: e1NIQX1PNWNIRFViTTFtUWlxT2U0UG1sbjdZUjRCVGc9

It contains a user gerrit and password gerrit

9) Create init.ldif file containing

#########################################################
# Root node for domain
#########################################################
dn: dc=MYHOST
objectClass: domain
objectClass: extensibleObject
objectClass: top
dc: MYHOST

#########################################################
# Root node for Users
#########################################################
# The node contains all users
dn: ou=Users,dc=MYHOST
objectClass: organizationalUnit
objectClass: top
ou: Users

#########################################################
# Root node for Groups
#########################################################
# Each group contains the user Ids assigned to the group
dn: ou=Groups,dc=MYHOST
objectClass: organizationalUnit
objectClass: top
ou: Groups

#########################################################
# Groups
#########################################################
dn: cn=admins,ou=Groups,dc=MYHOST
objectClass: groupOfUniqueNames
objectClass: top
cn: admins
description: Administrators group
uniquemember: uid=user1,ou=Users,dc=MYHOST

dn: cn=developers,ou=Groups,dc=MYHOST
objectClass: groupOfUniqueNames
objectClass: top
cn: developers
description: Developers group
uniquemember: uid=admin,ou=system
uniquemember: uid=user1,ou=Users,dc=MYHOST
uniquemember: uid=user1,ou=Users,dc=MYHOST

dn: cn=guests,ou=Groups,dc=MYHOST
objectClass: groupOfUniqueNames
objectClass: top
cn: guests
description: Guests group
uniquemember: uid=admin, ou=system

#########################################################
# Users
#########################################################
dn: uid=user1,ou=Users,dc=MYHOST
objectClass: organizationalPerson
objectClass: person
objectClass: extensibleObject
objectClass: uidObject
objectClass: inetOrgPerson
objectClass: top
cn: John Smith
givenname: John
sn: Smith
displayName: John Smith Jr.
mail: johnsmith@MYHOST
ou: Users
uid: user1
userpassword:: e1NIQX1zOXFuZTB3RXFWVWJoNEhRTVpIK0NZOHlYbWM9

dn: uid=user2,ou=Users,dc=MYHOST
objectClass: organizationalPerson
objectClass: person
objectClass: extensibleObject
objectClass: uidObject
objectClass: inetOrgPerson
objectClass: top
cn: Joe Doe
givenname: Joe
sn: Doe
displayName: terminator
mail: JoeDoe@MYHOST
ou: Users
uid: user2
userpassword:: e1NIQX1vWWdjQnU3SmJibVFISHUvNUJ4Q28vQ09uTFE9

Replace MYHOST with the name of the host. If your host have full domain name, then replace dc=MYHOST, with dc=mysubdomain,dc=mydomain,dc=com

The file describes a simple Groups/User hierarchy with 3 groups: admins,developers,users and 2 users: user1 (password:user1) and user2 (password:user2)

10) Using Apache Directory Studio import init.LDIF into LDAP server

11) Start tomcat service

service tomcat7 start

12) Stop tomcat service

service tomcat7 stop

13) Copy Bouncy castle jars to /usr/share/tomcat7/webapps/gerrit/WEB-INF/libs

cp /usr/share/gerrit/lib/bcprov-jdk16-144.jar /usr/share/tomcat7/webapps/gerrit/WEB-INF/lib

14) Start tomcat service and now you must be able to login to gerrit system with user1/user1 or user2/user2

15) Generating public/private keys.
Windows:
Download puttygen.exe and use it to generate a new private/public key. Use the menu Conversion / Export OpenSSH key to export the private key. Copy the OpenSHH public key (from the textbox)

Linux:

ssh-keygen -t rsa

Will generate /home/user/.ssh/id_rsa and /home/user/.ssh/id_rsa.pub
Copy the content of id_rsa.pub

16) Login into gerrit go to settigs, SSH key and paste the OpenSSH key (generated from the puttygen or ssh-keygen). Don't forget to click "Add"

17) Testing ssh connection. From Linux shell (or cygwin on windows boxes)

ssh -p 8418 -i <path to the private key> <gerrit IP/host>

18) Creating new project.

ssh -p 8418 -i <path to the private key> <gerrit IP/host> gerrit create-project -n <project name>

19) Go to Gerrit, choose "Admin" / "Projects" and select the newly created project.
Go to "Access" and add Submit,Push,Read permissions to "Registered Users" group

20) Cloning the newly created project for the first time.

git config --global user.name "Your Name"
git config --global user.email you@example.com
git config --global core.autocrlf false

git clone ssh://GERRIT_HOST:8418/PROJECT_NAME.git
cd PROJECT_NAME
git config remote.origin.push HEAD:refs/for/master
git config branch.master.remote origin
git config branch.master.merge refs/heads/master
echo Hello > readme.txt
git add readme.txt
git commit -m "Initial commit"
git push

After that the warning messages "You appear to have cloned an empty repository." or "remote HEAD refers to nonexistent ref, unable to checkout." will disappear.

FC15 post installation steps

Gnome shell 3

Showing date in taskbar

gsettings set org.gnome.shell.clock show-date true

Showing date in taskbar

gsettings set org.gnome.shell.calendar show-weekdate true

Show week numbers in calendar

gsettings set org.gnome.shell.calendar show-weekdate true

Show minimize, maximize buttons

gconftool-2 -s -t string /desktop/gnome/shell/windows/button_layout "menu:minimize,maximize,close"

Always show power off in menu

yum install gnome-shell-extensions-alternative-status-menu

More info about available extensions can be found here

Tweak-tool

yum install gnome-tweak-tool

Then use start it go to Desktop and enable "Have file manager handle the desktop"

Taskbar

yum install tint2

Then use gnome-session-properties utility to add tint2 to gnome auto start programs (/usr/bin/tint2)

Nautilus

Show hidden files

gsettings set org.gnome.nautilus.preferences show-hidden-files true

Show address bar instead of buttons for file path

gsettings set org.gnome.nautilus.preferences always-use-location-entry true

Configurations

Additional repositories

Add RPM fusion repos:

su -c 'yum localinstall --nogpgcheck http://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-stable.noarch.rpm http://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-stable.noarch.rpm'

Admin rights

Add sudo capabilities to current user:

usermod -a -G wheel `whoami`

Startup theme

Change the startup theme:

sudo yum install plymouth-theme*

sudo plymouth-set-default-theme --list

sudo plymouth-set-default-theme solar -R

Keyboard mappings

Install gconf-editor:

sudo yum install gconf-editor

Now open gconf-editor from command line and do following modifications:

windows + D to show desktop

Find the key "/apps/metacity/global_keybindings/show_desktop" and set the value to "<mod4>D"

windows + R to run command

Find the key "/apps/metacity/global_keybindings/panel_run_dialog" and set the value to ""<mod4>R"

windows + L to lock screen

Find the key "/apps/metacity/global_keybindings/run_command_1" (or any other number and set the value to ""<mod4>L". Find the key "/apps/metacity/keybinding_commands/command_1" and set the value to "gnome-screensaver-command -l"

Windows aliases

notepad

sudo alternatives --install /usr/bin/notepad notepad /usr/bin/gedit 1

explorer

sudo alternatives --install /usr/bin/explorer explorer /usr/bin/nautilus 1

cmd

sudo alternatives --install /usr/bin/cmd cmd /usr/bin/gnome-terminal 1

Installing additional software

Music player - XMMS

sudo yum install xmms xmms-faad2 xmms-mp3 xmms-pulse xmms-skins

Video players

mplayyer

sudo yum install mplayer gecko-mediaplayer mplayer-gui mencoder

VLC

sudo yum install vlc

Gnome-tweak-tool

sudo yum install gnome-tweak-tool

It can be used to change variety of options. Go to "Windows" and change "Current theme" to "Crux". Go to "File manager" and change "Have file manager handle desktop" to "Yes".

MS fonts

sudo yum install rpm-build cabextract ttmkfdir wget xfs

sudo rpm -ih http://dl.atrpms.net/all/chkfontpath-1.10.1-2.fc14.x86_64.rpm

sudo wget http://corefonts.sourceforge.net/msttcorefonts-2.0-1.spec

sudo rpmbuild -ba msttcorefonts-2.0-1.spec

sudo yum install --nogpgcheck /root/rpmbuild/RPMS/noarch/msttcorefonts-2.0-1.noarch.rpm

Chrome

Go to www.google.com/chrome and follow instructions

Flash

Go to Adobe flash and choose linux 64 (Step1) and YUM 64 (Step2) Install the downloaded RPM it will add the adobe YUM repos. Install the real flash player with:

yum install flash-plugin nspluginwrapper.x86_64 nspluginwrapper.i686 alsa-plugins-pulseaudio.i686 libcurl.i686

Now Firefox should be able to play flash video (try it with youtube) In order to make Chrome playing flash videos executes following commands:

mkdir /opt/google/chrome/plugins

ln -s /usr/lib64/mozilla/plugins/libflashplayer.so /opt/google/chrome/plugins/libflashplayer.so

Skype

Go to http://www.skype.com/intl/en/get-skype/on-your-computer/linux/downloading.fedora and follow instructions

Show system information as background - conky

sudo yum install conky

Then use gnome-session-properties utility to add conky to gnome auto start programs (/usr/bin/conky)A simple configuration file /etc/conky/conky.conf

alignment top_right

background no

border_width 1

cpu_avg_samples 2

default_color white

default_outline_color white

default_shade_color white

draw_borders no

draw_graph_borders yes

draw_outline no

draw_shades no

use_xft yes

xftfont DejaVu Sans Mono:size=12

gap_x 5

gap_y 60

minimum_size 5 5

net_avg_samples 2

no_buffers yes

out_to_console no

out_to_stderr no

extra_newline no

own_window_transparent yes

own_window yes

own_window_class Conky

own_window_type desktop

stippled_borders 0

update_interval 1.0

uppercase no

use_spacer none

show_graph_scale no

show_graph_range noTEXT

#${scroll 32 $nodename - $sysname $kernel on $machine | }

$nodename - $sysname $kernel

$hr

${color grey}Uptime:$color $uptime

${color grey}Frequency (in GHz):$color $freq_g

${color grey}RAM Usage:$color $mem/$memmax - $memperc% ${membar 4}

${color grey}Swap Usage:$color $swap/$swapmax - $swapperc% ${swapbar 4}

${color grey}CPU Usage:$color $cpu% ${cpubar 4}

${color grey}Temperature:$color $acpitemp% ${color grey}Fan speed:$color $acpifan

${color grey}Processes:$color $processes  ${color grey}Running:$color $running_processes

$hr

${color grey}File systems:

/ $color${fs_used /}/${fs_size /} ${fs_bar 6 /}

${color grey}Networking:

Up:$color ${upspeed eth0} ${color grey} - Down:$color ${downspeed eth0}

$hr

${color grey}Name              PID   CPU%   MEM%

${color lightgrey} ${top name 1} ${top pid 1} ${top cpu 1} ${top mem 1}

${color lightgrey} ${top name 2} ${top pid 2} ${top cpu 2} ${top mem 2}

${color lightgrey} ${top name 3} ${top pid 3} ${top cpu 3} ${top mem 3}

${color lightgrey} ${top name 4} ${top pid 4} ${top cpu 4} ${top mem 4}

All the information is found by googling. You can find some very useful tips here and here and here
Thanks guys!