List all services which are started at boot time

chkconfig --list | grep '3:on'

and…

Remove unwanted services

service service_to_remove stop

and

chkconfig service_to_remove off

That’s all.

Using netstat

netstat -tulpn

Using nmap

nmap -sT -O localhost

or if you want to check someone’s open ports:

nmap -sT -O server.you.want.to.check.com

Install/update GEMS/RubyGems

Download package from http://rubyforge.org/frs/?group_id=126 and unpack it.

Go inside new dir and run:

ruby setup.py

Now check Gems version on your system:

gem -v

Install/update Rails

gem update rails

and check do you have a new version of Rails:

rails -v

Install/update Ruby

sudo port install ruby

or

sudo apt-get install ruby

and check Ruby version:

ruby --version

Note: sometimes you need to check new version of these tools in new window/new terminal.

What I see is:

Couldn’t create database for {“encoding”=>”utf8″, “username”=>”my_username”, “adapter”=>”mysql”, “database”=>”my_database”, “pool”=>5, “password”=>”my_password”, “socket”=>”/tmp/mysql.sock”}, charset: utf8, collation: utf8_unicode_ci (if you set the charset manually, make sure you have a matching collation)

What I need to do?

Change “socket: /tmp/mysql.sock” to “host: localhost” in config/database.yml

So my config/database.yml looks like:

development:
  adapter: mysql
  encoding: utf8
  database: my_database
  pool: 5
  username: my_username
  password: my_password
  host: localhost

(...)

That’s all. Everything works fine.

Search packages

apt-cache search package-to-search

Install package

sudo apt-get install package-to-install

Remove package

if you want to keep the configuration files:

sudo apt-get remove package-to-remove

or if you want to remove everything (package and config files):

sudo apt-get --purge remove package-to-remove

Update package lists

sudo apt-get update

Update/upgrade package

sudo apt-get install package-to-update

or

apt-get upgrade

List all installed packages

dpkg --list

List individual package

exactly this package:

dpkg -l package-to-list

list of related packages:

dpkg -l *package-to-list*

What package owns the file?

dpkg -S /usr/bin/python

List dependencies of a package

apt-cache depends our-package

However since the beginning…

Install Ruby

sudo apt-get install ruby

Install RubyGems

sudo apt-get install rubygems

Install Rails

gem install rails

Make an application

rails myappname
cd myappname
ruby script/server

And… first error. What can I see on console?

=> Booting WEBrick
=> Rails 2.3.8 application starting on http://0.0.0.0:3000
/home/user/.gem/ruby/1.8/gems/rails-2.3.8/lib/initializer.rb:271:in `require_frameworks': no such file to load -- net/https (RuntimeError)
(...)

What is wrong?
I don’t have the Ruby SSL support installed.

What can I do?

sudo apt-get install libopenssl-ruby1.8

and that’s all. Everything works fine right now.

Open you nginx.conf (/usr/local/nginx/conf/nginx.conf) and edit/add few settings:

# buffer size, body size
client_body_buffer_size  1K;
client_header_buffer_size 1k;
client_max_body_size 1k;
large_client_header_buffers 2 1k;

# timeouts
client_body_timeout   10;
client_header_timeout 10;
keepalive_timeout     5 5;
send_timeout          10;

These values are too low in my opinion. However they come from this website, so they are worth to consider.

Now (descriptions come from cyberciti.biz):

• client_body_buffer_size – (default is 8k or 16k) The directive specifies the client request body buffer size.
• client_header_buffer_size – Directive sets the headerbuffer size for the request header from client. For the overwhelming majority of requests a buffer size of 1K is sufficient. Increase this if you have a custom header or a large cookie sent from the client (e.g., wap client).
• client_max_body_size – Directive assigns the maximum accepted body size of client request, indicated by the line Content-Length in the header of request. If size is greater the given one, then the client gets the error “Request Entity Too Large” (413). Increase this when you are getting file uploads via the POST method.
• large_client_header_buffers – Directive assigns the maximum number and size of buffers for large headers to read from client request. By default the size of one buffer is equal to the size of page, depending on platform this either 4K or 8K, if at the end of working request connection converts to state keep-alive, then these buffers are freed. 2x1k will accept 2kB data URI. This will also help combat bad bots and DoS attacks.
• client_body_timeout – Directive sets the read timeout for the request body from client. The timeout is set only if a body is not get in one readstep. If after this time the client send nothing, nginx returns error “Request time out” (408). The default is 60.
• client_header_timeout – Directive assigns timeout with reading of the title of the request of client. The timeout is set only if a header is not get in one readstep. If after this time the client send nothing, nginx returns error “Request time out” (408).
• keepalive_timeout – The first parameter assigns the timeout for keep-alive connections with the client. The server will close connections after this time. The optional second parameter assigns the time value in the header Keep-Alive: timeout=time of the response. This header can convince some browsers to close the connection, so that the server does not have to. Without this parameter, nginx does not send a Keep-Alive header (though this is not what makes a connection “keep-alive”).
• send_timeout – Directive assigns response timeout to client. Timeout is established not on entire transfer of answer, but only between two operations of reading, if after this time client will take nothing, then nginx is shutting down the connection.

That will be a quick tip…

First… build firewall on your server.

Then… install and turn on SELinux.

SELinux is a kernel security extension, which can be used to guard against misconfigured or compromised programs. It comes with Mandatory Access Control (MAC) system that improves the traditional UNIX/Linux DAC (Discretionary Access Control) model.

How to install it on Ubuntu?
Using apt-get.

sudo apt-get install selinux

and reboot system.

Now you can configure and enable it.

First… download MacPorts and run the install it on your Mac.

And then…

sudo port install jpeg

This will install libjpeg.

And after that it’s time for PIL.

sudo /opt/local/bin/port install py25-pil

Probably you’ll need to supplement your PYTHONPATH with the location of the python libraries that MacPorts uses. In your /etc/profile or ~/.profile, add the following line:

export PYTHONPATH=/opt/local/lib/python2.5/site-packages

and that’s it. Now everything should be fine.

Helpful resources:

• http://rezmuh.sixceedinc.com/2009/04/setting-up-pil-with-libjpeg-on-mac-os-x-leopard.html
• http://emmby.blogspot.com/2008/05/installing-python-pil-on-mac-os-x-1052.html

I found lots of discussions about that, however none of them were enough for me. Some of the discussions:

• http://bugs.developers.facebook.com/show_bug.cgi?id=8184
• http://bugs.developers.facebook.com/show_bug.cgi?id=8691

And now… my solution:

Log in to Facebook, create new app, create fan page.

Now you are ready.

Add app to your fan page.

Go to http://www.facebook.com/apps/application.php?id=ID_OF_YOUR_APP.

Find link ‘Add to my Page’ on the left, click on it. Find your page on the list and click on ‘Add to page’ next to this page.

Set application type

Go to http://www.facebook.com/developers/editapp.php?app_id=ID_OF_YOUR_APP.

Choose ‘Web’ next to ‘Application type’ and click on ‘Save Changes’ button.

Add permissions to your app

Prepare special link:

http://www.facebook.com/connect/prompt_permissions.php?api_key=YOUR_API_KEY&v=1.0&next=http://www.facebook.com/connect/login_success.html?xxRESULTTOKENxx&display=page&ext_perm=publish_stream,offline_access&enable_profile_selector=1&profile_selector_ids=ID_OF_YOUR_PAGE

replace YOUR_API_KEY for an API KEY of your application and ID_OF_YOUR_PAGE for an id of your page

Run this URL in your web browser. Click on ‘Allow’.

You should see a message: ‘Success’.

Check everything

Go to http://developers.facebook.com/tools.php?app_id=335851346097 and check your permissions.

Choose your application, change ‘Response Format’ to JSON, choose method ‘users.hasAppPermission’, fill publish_stream in ext_perm and id of your page in uid.

You should see result: 1.

That means that everything is ok.

Write a code

Right now I will show how to create script in python (with PyFacebook), but the code is really similar to that from other programming languages.

def add_to_fb();
	import facebook
	fb = facebook.Facebook('YOUR_API_KEY', 'YOUR_SECRET_KEY')
	fb.auth.createToken()
	fb.login(popup=False)

	#print 'offline access...'
	#b.request_extended_permission('offline_access')
	#print 'publish stream...'
	#fb.request_extended_permission('publish_stream')

	print 'get session...'
	fb.auth.getSession()

	print 'add...'

	try:
		id_of_message = fb.stream.publish(message='my test message', uid=ID_OF_YOUR_PAGE)
	except Exception, e:
		error_code = None
		try:
			error_code = e.code
		except AttributeError:
			pass

		if error_code:
			print  "Facebook returned an error - sorry! %s %s" % (str(e.code), repr(e))
		else:
			print  "Facebook returned an error - sorry (no error code)! %s" % (repr(e))
	else:
		print id_of_message

And that’s all. Try to use it.

Sometimes it’s necessary to use request_extended_permission() (if we want to add privileges to our user), so you can uncomment these two lines.

Lots of hours… but at last – success.