So we decided to install Zend Server CE as it has more or less the same settings over different platforms. I've had some bad experiences installing ZSCE on a system that already had apache installed via apt, but after a clear install of Karmic, ZF was running like a charm. The install process described in the online documentation works great.

After install is done, make sure to symlink php, pecl, pear and phpize so you can access them system wide:

sudo ln -s /usr/local/zend/bin/zendctl.sh /usr/sbin/zendctl
sudo ln -s /usr/local/zend/bin/pear /usr/sbin/pear
sudo ln -s /usr/local/zend/bin/pecl /usr/sbin/pecl
sudo ln -s /usr/local/zend/bin/php /usr/sbin/php
sudo ln -s /usr/local/zend/bin/phpize /usr/sbin/phpize

At this point you should be able to run php -i in terminal and the phpinfo will be displayed.

Next step is to install xdebug via pecl by running:

sudo pecl install xdebug

If all went well you should have the xdebug library located at /usr/local/zend/lib/php_extensions/xdebug.so . If you don't have it there, then something went wrong and you should NOT continue reading. This issue must be sorted first.

Next you need to comment out the 1st line of /usr/local/zend/etc/conf.d/debugger.ini so it looks like this:

#open editor
gksu gedit /usr/local/zend/etc/conf.d/debugger.ini

# this is how the 1st two lines should look afterwards
; register the extension to be loaded by Zend Extension Manager
;zend_extension_manager.dir.debugger=/usr/local/zend/lib/debugger

Xdebug needs to be loaded before Zend Extension Manager, that's why you need to add the following line just on top of the /usr/local/zend/etc/ext.d/extension_manager.ini

#open the editor
gksu gedit /usr/local/zend/etc/ext.d/extension_manager.ini

#add this line on 1st line:
zend_extension=/usr/local/zend/lib/php_extensions/xdebug.so

#save the file

Restart zend server by running:

sudo /etc/init.d/zend-server restart

You can check if xdebug is working like so:

php -i |grep xdebug

The output should be something similar to this:

xdebug
xdebug support => enabled
xdebug.auto_trace => Off => Off
xdebug.collect_includes => On => On
xdebug.collect_params => 0 => 0
xdebug.collect_return => Off => Off
xdebug.collect_vars => Off => Off
xdebug.default_enable => On => On
xdebug.dump.COOKIE => no value => no value
xdebug.dump.ENV => no value => no value
xdebug.dump.FILES => no value => no value
xdebug.dump.GET => no value => no value
xdebug.dump.POST => no value => no value
xdebug.dump.REQUEST => no value => no value
xdebug.dump.SERVER => no value => no value
xdebug.dump.SESSION => no value => no value
xdebug.dump_globals => On => On
xdebug.dump_once => On => On
xdebug.dump_undefined => Off => Off
xdebug.extended_info => On => On
xdebug.idekey => mimir => no value
xdebug.manual_url => http://www.php.net => http://www.php.net
xdebug.max_nesting_level => 100 => 100
xdebug.profiler_aggregate => Off => Off
xdebug.profiler_append => Off => Off
xdebug.profiler_enable => Off => Off
xdebug.profiler_enable_trigger => Off => Off
xdebug.profiler_output_dir => /tmp => /tmp
xdebug.profiler_output_name => cachegrind.out.%p => cachegrind.out.%p
xdebug.remote_autostart => Off => Off
xdebug.remote_enable => Off => Off
xdebug.remote_handler => dbgp => dbgp
xdebug.remote_host => localhost => localhost
xdebug.remote_log => no value => no value
xdebug.remote_mode => req => req
xdebug.remote_port => 9000 => 9000
xdebug.show_exception_trace => Off => Off
xdebug.show_local_vars => Off => Off
xdebug.show_mem_delta => Off => Off
xdebug.trace_format => 0 => 0
xdebug.trace_options => 0 => 0
xdebug.trace_output_dir => /tmp => /tmp
xdebug.trace_output_name => trace.%c => trace.%c
xdebug.var_display_max_children => 128 => 128
xdebug.var_display_max_data => 512 => 512
xdebug.var_display_max_depth => 3 => 3

Note the xdebug support => enabled on line 2.

Hope that helps