Varun's Blog

Apache Config Steps – Run multiple domains on same ip

Varun — Wed, 16 Nov 2011 11:40:30 +0000

Suppose you want to point abc.mydomain.com and mydomain.com to same machine/ip, but to different applications. There are multiple ways to achieve this (basically with same config settings but in different files). I am giving one way here that worked for me:

* Go to /etc/apache2/sites-available
* open a file abc.mydomain.com.conf
* copy this to abc.mydomain.com.conf, make changes to folder path domain name etc. and Save the file


DocumentRoot /var/www/abcappfolder/

ServerAdmin admin@mydomain.com

ServerName abc.mydomain.com

ServerAlias www.abc.mydomain.com
Options FollowSymLinks

AllowOverride None
#we want specific log file for this server

CustomLog /var/log/apache2/abc.com-access.log combined

ErrorLog /var/log/apache2/abc.com-error.log

* Now create another file mydomain.com.conf
* copy this to mydomain.com.conf, make changes to folder path domain name etc. and Save the file. Note that here I am assuming mydomain.com will actually redirect to an app server (like tomcat or jboss) running on port 8080, that’s why you see ProxyPass statements:


DocumentRoot /var/www/mysecondapp/

ServerAdmin admin@mydomain.com

ServerName mydomain.com

ServerAlias www.mydomain.com
Options FollowSymLinks

AllowOverride None
ProxyPass / http://127.0.0.1:8080/

ProxyPassReverse / http://127.0.0.1:8080/

ProxyPreserveHost on
#if using awstats

ScriptAlias /awstats/ /usr/lib/cgi-bin/

#we want specific log file for this server

CustomLog /var/log/apache2/mydomain.com-access.log combined

ErrorLog /var/log/apache2/mydomain.com-error.log
# if your machine's name is also mydomain.com

# then you need to use config settings below

# otherwise site will NOT be accessible with mydomain.com

# (although it will be accessble as www.mydomain.com)

RewriteEngine on

RewriteCond %{HTTP_HOST} ^mydomain.com [NC]

RewriteRule ^(.*)$ http://www.mydomain.com/$1 [L,R=301]

* on command line run these commands to enable these 2 configs:

a2ensite abc.mydomain.com.conf a2ensite mydomain.com.conf

This creates symlinks to the 2 config files in /etc/apache2/sites-enabled folder
You can create the same symlinks manually also like this:

cd /etc/apache2/sites-enabled ln -s /etc/apache2/sites-available/abc.mydomain.com.conf abc.mydomain.com.conf ln -s /etc/apache2/sites-available/mydomain.com.conf mydomain.com.conf

* Following step is required only if your machine’s name is also mydomain.com (that means you sftp or ssh to your machine using mydomain.com). In this case I was not able to access my site using mydomain.com in browser. Hence I did this which worked, there may be a different way to solve this problem though:

remove symlink to ln -s /etc/apache2/sites-available/default file from /etc/apache2/sites-enabled folder. You can use rm command or you can run this command

a2dissite default

You do not need to do this for sub-domains (like abc.mydomain.com)

* Restart apache (/etc/conf.d/apache restart)
* Your sites should be accessible now

Note : If it does not work make sure you do not have ProxyPass statements inside httpd.conf or a conf file in /etc/apache2/conf.d to redirect URL

Fatal error: Allowed memory size of 16777216 bytes exhausted

Varun — Wed, 16 Nov 2011 11:08:07 +0000

You need to change the maximum memory allowed to a php script to run.
For this you need to open your php.ini (location of this file will depend on where php is installed on your machine). In my case php.ini is in /etc/php5/apache2/php.ini

Open /etc/php5/apache2/php.ini

search for memory_limit

change 16M to 32M

save file, you are good to go!

Steve Jobs

Varun — Tue, 11 Oct 2011 02:43:49 +0000

Technology serves everyone not only companies or computer geeks. Sitting in a bus or subway with music to ears via ipod, was technology ever that close to public? And the one man who deserves credit more than anyone else is legendary Steven Paul Jobs.

Steve Jobs was a truly technical person. Best depiction of his talent was in innovation of technical ideas and their implementation. He worked on a computer board with Stephen Wozniak before coming up with Apple II computer in 1977, a much advanced computer at that time. with Macintosh his aim was to build a cheaper computer with powerful GUI. NeXTSTEP was his idea of a Unix based operating system. And MAC OS X is basically MAC with NeXTSTEP together. iMac, iPod, iPhone and then iPad apart from several software innovations from Steve and his company took the media world to another level.

As a manager Steve was considered to be erratic and hyper sensitive. To change self nature is a very difficult job but Steve proved he could do it by becoming a very capable CEO of Apple in last decade.

People like Steve are true genius who with their hard work and rare brain help the world make enormous progress in little time. It is sad for the world to not to have him anymore. Steve Jobs will always be remembered as a true visionary.

Javascript – extract Year from Date

Varun — Fri, 24 Jun 2011 18:14:35 +0000

If you want to extract year from Date in Javascript, try getFullYear() method instead of getYear(), see the output below on Firefox and Chrome…

Here's the code:

CSS, DIV and Table Wrap Problem

Varun — Wed, 18 May 2011 22:35:58 +0000

I had this table within a DIV














The Business Communication System bundle combines an ADTRAN NetVanta 7100 or NetVanta 7060 with the NetVanta Unified Communications software to give the customer Unified Messaging providing access to voice mail and faxes within an email or desktop client. This solution provides a Fax Server, Personal Assistants, Graphical Drag-and-Drop Service Creation, Call Redirection Services, and Notifications. This solution requires a separate server to run the UC software. A server is not included in the BCS bundle.

Click here for more information.

And CSS properties were:

div.tooltip { position: absolute; z-index: 1; white-space:pre-wrap; } table.tooltip { border-collapse: collapse; width: 250px; color: #000; font-size: 10pt; border-width: 4px; border-color: #013777; }

This is what was showing up on screen

After some research, I changed DIV css to this:

div.tooltip { position: absolute; z-index: 1; visibility: hidden; white-space:pre-wrap; }

and now it wrapped text without any problem and I see this now (white-space:pre-wrap; keeps white spaces as entered and wraps text when required):

2010 in review

Varun — Mon, 03 Jan 2011 05:37:19 +0000

Computers directory

The stats helper monkeys at WordPress.com mulled over how this blog did in 2010, and here’s a high level summary of its overall blog health:

The Blog-Health-o-Meter™ reads Wow.

Crunchy numbers

A helper monkey made this abstract painting, inspired by your stats.

A Boeing 747-400 passenger jet can hold 416 passengers. This blog was viewed about 3,100 times in 2010. That’s about 7 full 747s.

In 2010, there were 15 new posts, growing the total archive of this blog to 41 posts.

The busiest day of the year was December 22nd with 524 views. The most popular post that day was DAO with JPA (and service layer/EJB3-Session Beans) or not.

Where did they come from?

The top referring sites in 2010 were dzone.com, coderanch.com, programmersheaven.com, facebook.com, and linkedin.com.

Some visitors came searching, mostly for scea risk and mitigation, scea 5, linux truncate log file, ejb3 dao, and scea 5 part 3.

Attractions in 2010

These are the posts and pages that got the most views in 2010.

DAO with JPA (and service layer/EJB3-Session Beans) or not June 2010
5 comments

SCEA 5 – My 2 cents March 2010

Approach Java (1) March 2009

Myself March 2009

Host Credentials ERROR Invalid username and or password Oracle 11g August 2009

ORA-28001: the password has expired

Varun — Mon, 13 Dec 2010 06:16:55 +0000

That’s the error you get for oracle user for whom password is expired.

One Solution – Connect using sqlplus to set new password, you can even use the same password you had earlier.

$ sqlplus

SQL*Plus: Release 11.2.0.1.0 Production on Mon Dec 13 01:12:07 2010

Enter user-name: myuser
Enter password:
ERROR:
ORA-28001: the password has expired

Changing password for myuser
New password:
Retype new password:
Password changed

Connected to:
Oracle Database 11g Release 11.2.0.1.0 – 64bit Production

Oracle Privileges to Import/Export data into any tablespace

Varun — Fri, 10 Dec 2010 08:40:51 +0000

Generally we can have a single user with DBA rights to import/export (using imp/exp utilities) data into any tablespace instead of assigning these privileges to every user account.

Suppose you have an oracle user appdba. Grant DBA role to appdba and you can use this user to import data into any tablespace like this:

imp appdba/pwd file=xyz.dmp fromuser=username touser=targetusername

Similarly export

exp appdba/pwd file=xyz.dmp owner=username

where owner is the username for which you want to export data

ORA-01996: GRANT failed: password file is full

Varun — Fri, 10 Dec 2010 08:35:15 +0000

If you face this error that means you have exhausted allowed number of users with sysdba privileges and are trying to create another one. Most probably you do not need that many user accounts with sysdba privileges.

run this query:

Select * from v$pwfile_users;

It will show you the list of all users with sysdba and sysoper roles.

To fix this:
Edit existing user accounts and under “System Privileges” remove all, you will probably need only “Unlimited Tablespace” system privilege for user or you can assign a fixed quote. Secondly make sure only “Connect” role is specified under Roles. This should be enough for most of user activities.

eclipse stuck at initializing java tooling

Varun — Fri, 03 Dec 2010 08:43:54 +0000

Eclipse 3.6 helios:

I did not update anything in working eclipse but don’t know what happened and it got stuck in something for which it did not display any description. When I restarted, it got stuck at “initializing java tooling”

Restarting with eclipse -clean did not help.
But I noticed following error in console when I restarted it from command line

java.io.FileNotFoundException: /opt/public/technology/epp/epp_build/36/eclipse.S-3.6RC4-201006031500/artifacts.xml (No such file or directory)
at java.io.FileOutputStream.open(Native Method)
at java.io.FileOutputStream.(FileOutputStream.java:179)
at java.io.FileOutputStream.(FileOutputStream.java:131)…..
….
…

There is not much on google about this error except restarting eclipse with -clean flag or cleaning your projects.

I grep-ed within eclipse for any file that contains reference to : /opt/public/technology/epp/epp_build/36/eclipse.S-3.6RC4-201006031500

find . -name ‘*.*’ -exec grep -s “/opt/public/technology/epp/epp_build/36/eclipse.S-3.6RC4-201006031500″ {} \; -print

File found was this:

/opt/eclipse/p2/org.eclipse.equinox.p2.engine/profileRegistry/epp.package.java.profile/.data/.settings/org.eclipse.equinox.p2.artifact.repository.prefs

What I did was to comment out the line that contained above path (following line):

repositories/file\:_opt_public_technology_epp_epp_build_36_eclipse.S-3.6RC4-201006031500/uri=file\:/opt/public/technology/epp/epp_build/36/eclipse.S-3.6RC4-201006031500/

And restarted, after which problem was resolved.

One more thing, now when I open this file again that line is uncommented (by eclipse during restart I guess), but problem is not there!! Don’t have time enough to go and figure out these mysteries, let me know if you have more info.

Subclipse Update Problem – eclipse 3.6 helios

Varun — Tue, 09 Nov 2010 09:39:13 +0000

Problem:

An error occurred while collecting items to be installed
session context was:(profile=epp.package.java, phase=org.eclipse.equinox.internal.p2.engine.phases.Collect, operand=, action=).
No repository found containing: osgi.bundle,org.eclipse.team.cvs.ssh,3.2.100.I20090508-2000

Solution:

When you update there is a checkbox on update window (last item):

“Contact all update sites during install to find required software”

Uncheck it – This should fix the problem and save a lot of time as well!!

svn switch –relocate syntax and “client is too old to work with working copy”

Varun — Tue, 09 Nov 2010 09:33:06 +0000

I don’t think there is a provision in subclipse plugin to support –relocate tag with switch. You can use svn command line tool for this as below.

Example 1:

* Go inside the folder on command line (suppose folder svn+ssh://abc.com/home/SVN/myproj/trunk is checked out on local machine under folder myproject):

cd myproject

* Run this command to switch the SVN pointer from svn+ssh://abc.com/home/SVN/myproj/trunk to svn+ssh://def.com/home/svn/myproj/trunk

svn switch --relocate svn+ssh://abc.com/home/SVN/myproj/trunk svn+ssh://def.com/home/svn/myproj/trunk .
You should be done now!!
Just go to eclipse and refresh project. You can restart eclipse if there’s still some problem. For other exceptions see ‘troubleshooting’ section below.

Example 2: In case your local machine username and svn username are different:

svn switch --relocate svn+ssh://abc.com/home/SVN/myproj/trunk svn+ssh://SVNUserName@def.com/home/svn/myproj/trunk .

Troubleshooting

If you face this error:

svn: This client is too old to work with working copy’ error without upgrading Subversion

This most probably means you have higher version of svn client installed somewhere (like subclipse) while your command line client is of lower version. One fix for this is:

* Downgrade code to previous version
* Then use svn switch as above

How to downgrade:
* Download Python script from this location:

http://svn.apache.org/repos/asf/subversion/trunk/tools/client-side/change-svn-wc-format.py

Suppose you download it under /opt/myscripts

* Make it executable

chmod +x /opt/myscripts/change-svn-wc-format.py

* Now go to project folder again and run this command to downgrade code to 1.5
(assuming your current command line client is at 1.5)

/opt/myscripts/change-svn-wc-format.py . 1.5

Now you can run svn switch as above

apt-get install subversion – Package subversion is not available

Varun — Tue, 09 Nov 2010 09:08:38 +0000

On Ubuntu

$apt-get install subversion

Reading package lists… Done
Building dependency tree
Reading state information… Done
Package subversion is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or is only available from another source

Solution

Go to System > Administration > Software Sources

Check all options (main, universe, restricted and multiverse – actually only main is required but in case you run into more problems, check all), close

Now run apt-get install subversion, it should work!!

Generating ssh keys – steps

Varun — Thu, 16 Sep 2010 07:19:57 +0000

These are the steps:

Suppose you want to connect from machine X to machine Y as userme.

* login to X as userme
* At /home/userme run this command:

ssh-keygen -t rsa

This will generate 2 files in /home/userme/.ssh folder

id_rsa
id_rsa.pub

* open id_rsa.pub file and copy its contents – this is the public key

* Now login to machine Y as userme, open file /opt/userme/.ssh/authorized_keys – If path/file does not exist create it

* Append contents copied from id_rsa.pub on machine X to the end of authorized_keys file

* Save file and exit

Now you can ssh to machine Y from X without entering credentials.

Javascript – invoking onclick event explicitly

Varun — Tue, 14 Sep 2010 08:54:26 +0000

Suppose an image with id “closeimg” has a Javascript function test() attached to it with ‘onclick’ event.
To invoke that function with code following does not work (not in Mozilla and Chrome at least):

document.getElementById("closeimg").click();

Solution is this:

document.getElementById("closeimg").onclick. call(document.getElementById("closeimg"));

document.getElementById("closeimg").onclick. apply(document.getElementById("closeimg"));

where document.getElementById("closeButton").onclick is the function itself (test() in this case) and call/apply method is to call the function on element passed as argument – in this case we want to call it on image.