And finally:
rm -vf $LIST

We encourage you to start looking at your site’s speed (the tools above provide a great starting point) — not only to improve your ranking in search engines, but also to improve everyone’s experience on the Internet.

The post lists a number of tools everyone should be using already, such as YSlow, google’s own PageSpeed, online speed waterfall diagram tool and webmaster tools. Webmaster tools recently added a beta feature which provides data about your sites speed relative to other sites on the internet.

Here is a sample report:

webmaster tools page speed chart

Performance overview
On average, pages in your site take 6.3 seconds to load (updated on Apr 11, 2010). This is slower than 83% of sites. These estimates are of medium accuracy (between 100 and 1000 data points). The chart below shows how your site’s average page load time has changed over the last few months. For your reference, it also shows the 20th percentile value across all sites, separating slow and fast load times.

Linus System admin blog will have a series on page speed improvement.  Stay tuned!

I’ll assume that you have installed apc already, if this is not the case this will probably be something as simple as running
pecl install apc
or downloading the archive from pecl and running:
phpize; ./configure; make; make install

The APC extension needs to be enabled either in php.ini or in one included file with a line like this:
extension=apc.so
there are many other parameters that apc can be fine tuned (see the official doc for more info), but without any other change, just with this line apc will be enabled on all the vhosts on the server.

Disabling some vhosts from using APC
- if we want to disable APC for a particular vhost we just have to add to the vhost config or to .htaccess:
php_flag apc.cache_by_default Off

Enabling APC only on some vhosts
- if we want to have APC disabled by default globally we will have in php.ini:

extension=apc.so
[apc]
apc.cache_by_default=0 # disable by default
... other apc settings...

and we will enable APC for the particular vhost config or using .htaccess using:
php_flag apc.cache_by_default On

Hopefully you found this post useful and this will give you a reason to use APC with more confidence knowing that you have the granularity to disable/enable it as needed in a shared environment.

Since the mail server for these accounts are pointing to other servers, I deleted all the email accounts, forwarders, mailinglists, etc. After this I’ve seen sending error/failure messages from mail logs of the said accounts It shows ‘fixed_login authenticator failed for hostxx’ [535 Incorrect authentication data].

In order to enable error reporting for your php script or application include inside your code the following lines:
error_reporting(E_ALL);
ini_set("display_errors", 1);
and this will result in displaying in the browser any errors your application might have.

ps: once you are done with this and fixed the issue, don’t forget to remove the error reporting lines, as we don’t want our users/clients to see errors in the browser in case something went wrong.

There are no major changes in this update, mostly bug fixes and security fixes, and it should be a quick and easy upgrade for most people still running the 4.x branch (you should really consider upgrading to 5.x ).

location /images {
	valid_referers   none  blocked  server_names  mydomain.com www.mydomain.com;
	if ($invalid_referer) {
		return   403;
	}
	... else serve the content
}

This works fine in this simple case; but what if we need to list more sub-domains? like images.mydomain.com an static.mydomain.com, etc? It would be nice to be able to use a regexp for this, right? Fortunately nginx has support for this and this can be done using a valid_referers line like:
valid_referers none blocked server_names ~(mydomain.com)

And this will match all the subdomains *.mydomain.com. Going even further you might want to allow google as a referrer for you content. Still google has so many subdomains and even different domains (like google.com, google.de, etc.) For this we could add ~(google.) and have our final configuration look like this:

location /images {
	valid_referers   none  blocked  server_names  ~(mydomain.com|google.);
	if ($invalid_referer) {
		return   403;
	}
	... else serve the content
}

This simple example shows how powerful the configuration of nginx is and how easy it is to do things that are rather impossible with other similar softwares.

If the remote ssh server is not running on the default ssh port (tcp 22) then this needs a little tweaking to get it working. Normally I was expecting that adding a custom entry for the svn server in the /etc/ssh/ssh_config file with the appropriate port would make this work on the fly without changing the command line; or if not, adding the ssh port in ‘telnet like’ way: server:port would make a difference. Still none of those worked and in order to get this working I had to dig into the subversion documentation on how we can define a special tunnel.

We can define a new tunnel in the svn configuration file (.subversion/config):
[tunnels]
sshtunnel = ssh -p <port>

And after this we can use svn as usual but with a url like svn+sshtunnel:// :
svn co svn+sshtunnel://user@server/repo .

See what its all about here:

System Administrator Appreciation Day, also known as Sysadmin Day, SysAdminDay or SAAD, was created by system administrator Ted Kekatos. Kekatos was inspired to create the special day by a Hewlett-Packard magazine advertisement in which a system administrator is presented with flowers and fruit-baskets by grateful co-workers as thanks for installing new printers.

Here is one of our own getting some appreciation from our colleagues.

Max, our gets nominated as a favorite linux system administrator by some of his office fans

So don’t forget to buy your system administrator a coffee, beer, donut, or whatever he prefers, and dont ask any stupid questions tomorrow.

The system administrator song

And here is a link to another System administrator song from the UK

http://www.ukuug.org/sysadminday/