Daniele Demichelis

Svn toolkit

danidemi — Wed, 14 Apr 2010 08:14:26 +0000

This is a quick SVN reference I update regularly, with the commands I use more. I hope you’ll find it useful.

Task: Browse a remote repository

svn ls svn+ssh://[alias]/[path]

Task: create a directory on a remote repository

svn mkdir -m "[message]" svn+ssh://[alias]/[path_to_new_dir]

Task: import a directory

svn import -m "[message]" [path_to_be_imported] [repository_url]

Task: check out

svn checkout [repository url]

Assert statement in Objective C

danidemi — Fri, 19 Mar 2010 15:40:40 +0000

Hi,
if you like to use assertions in your source code, but you miss this feature in ObjectiveC, give a look to this small class.
Assert.h

#import
@interface Assert : NSObject {
}
+(void)that:(BOOL)expr;
@end

Assert.m

#import "Assert.h"
@implementation Assert
+(void)that:(BOOL)expr{
if (!expr) {
[NSException raise:@"Failed assertion." format:@"Failed assertion", nil];
}
}
@end

As you can see, there’s only one static method that you can use wherever you want.
In this snippet here’s an example how to use it.

#import "Assert.h"
-(void)doSomething{
[Assert that:()];
}

Get rid of MantisBT date_default_timezone_get() warning

danidemi — Thu, 18 Mar 2010 10:13:42 +0000

If you installed a MantisBT instance on a system with a recent PHP version, there’s the chance you get a warning saying:

SYSTEM WARNING: date_default_timezone_get(): It is not safe to rely on the system’s timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected ‘Europe/Berlin’ for ‘CET/1.0/no DST’ instead

A quick way to get rid of this is to set an explicit time zone.

Just open the config_inc.php file and add the date_default_timezone_set() line.

date_default_timezone_set("Europe/Rome");
$g_hostname = 'localhost';
$g_db_type = 'mysql';
$g_database_name = 'db_name';
$g_db_username = 'user';
$g_db_password = 'secret';
?>

Please refer to this list to discover the available time zones.

Linux Shell Survival Toolkit

danidemi — Thu, 18 Mar 2010 10:00:24 +0000

Hi, having a strong Windows background, I hardly remember all options of the huge set of commands available in the Linux shell… so, I’m slowly but steadily building up this Survival Toolkit. Hope it helps.

File and directory management

Symbolic link

Sometimes it is useful to hide the real location of a directory. For instance you could have various folders containing different versions of the same software. So, for instance you got /opt/package-1.2, /opt/package-1.3, /opt/package/1.4beta. But maybe you like to have an /opt/package folder that should contain the version that should be currently used, so, you can use a symbolic link:

ln -s

In our case

ln -s /opt/package-1.3 /opt/package

Compressed files

Often one downloads an open source project as a bundle which extension is .tar.gz. Here’s how to inflate it.

tar xvf [filename.tar]

Playing around with twitter list

danidemi — Wed, 17 Mar 2010 17:01:44 +0000

Hi to you all, I was playing around with the twitter list feature. It happens I’m a big F1 fan, so, I built up a list with all tweetters that I think deserve to be followed. Here’s the link: http://twitter.com/#/list/escher75/f1.

Ruby on CentOS

danidemi — Wed, 17 Mar 2010 14:07:36 +0000

In these days I’m trying to install Ruby on Rails on our CentOS production server. What I really don’t like very much about CentOS are its pretty outdated packages installable via yum. This time proved to be the same… it’s seems that the Ruby available on CentOS via yum is a version released during 2006.
In the first place I tried to compile Ruby from sources, but this proved a little too much messy for me. In the end I stumbled upon Ruby Enterprise Edition and I gave it a try.
What I liked most about it was that it worked perfectly just out of the box and that all Ruby files go inside a single directory, so it’s pretty easy to move from a version to another even if not using yum.
This is a brief tutorial about how to install Ruby Enterprise Edition on CentOS.

Get rid of any Ruby previously installed

First of all let’s remove any Ruby installation already present on our CentOS.
We can ask Yum to give us a list of Ruby related packages currently installed.

yum list | grep installed | grep ruby

My server answered that way, but obviously yours can show other answers.

ruby.i386 1.8.5-5.el5_3.7 installed
ruby-devel.i386 1.8.5-5.el5_3.7 installed
ruby-libs.i386 1.8.5-5.el5_3.7 installed
ruby-mode.i386 1.8.5-5.el5_3.7 installed

Time to gently ask to Yum to remove all those Ruby packages.

yum erase ruby
yum erase ruby-devel
yum erase ruby-libs
yum erase ruby-mode

We can now start with the Enterprise Ruby installation.

Download and install Enterprise Ruby

There is really nothing deeply interesting here. Just download the sources, unpack them, compile them and set some useful links.

mkdir -p ~/Temp/Sources
cd ~/Temp/Sources
wget http://rubyforge.org/frs/download.php/68719/ruby-enterprise-1.8.7-2010.01.tar.gz
tar xzvf ruby-enterprise-1.8.7-2010.01.tar.gz
./ruby-enterprise-1.8.7-2010.01/installer

At the end we should have a working Ruby installation.
Let’s create some useful link.

ln -s /opt/ruby-enterprise-1.8.7-2010.01/bin/rake /usr/bin/rake
ln -s /opt/ruby-enterprise-1.8.7-2010.01/bin/gem /usr/bin/gem
ln -s /opt/ruby-enterprise-1.8.7-2010.01/bin/rails /usr/bin/rails
ln -s /opt/ruby-enterprise-1.8.7-2010.01/bin/ruby /usr/bin/ruby
ln -s /opt/ruby-enterprise-1.8.7-2010.01/bin/irb /usr/bin/irb

Worth reading

Cristian Livadaru’s blog post about the topic.
Install the available Ruby via Yum
Enterprise Ruby download page

Database testing with Mono and NUnit

danidemi — Fri, 12 Mar 2010 16:03:37 +0000

In these days I’m trying to rewrite an old application using Mono.
I’m currently a newbie about Mono and the .Net world, but I happily noticed that the Mono environment come with a bundled interface to NUnit, so I can keep on writing tests as I’m slowly but steadily getting used to.
After having put together a bunch of classes and relative and unit tests, it was time to write the first integration test. I needed to put the development database in a known state before running the test, so I came up with the following class, that I’d like to share with you.

using System;
using System.Collections;
using NUnit.Framework;
using System.IO;
using System.Data;
using System.Data.SqlClient;
namespace TellItMailer{
public class TestDbSetup{
public void SetUpDbForTest(object test){
String path = test.GetType().FullName + ".sql";
path = path.Replace(this.GetType().Namespace + ".", "");
path = "/home/danidemi/workspace/TellItMailer/Tests/" + path;
//Read the script
String script = "";
using (StreamReader sr = File.OpenText(path)){
string s = "";
while ((s = sr.ReadLine()) != null){
script = script + s;
}
}
string connectionString =
"Server=192.168.75.128\\SQLEXPRESS;" +
"Database=TellIt_test;" +
"User ID=user;" +
"Password=password;";
IDbConnection dbcon;
using(dbcon = new SqlConnection(connectionString)){
dbcon.Open();
using (IDbCommand dbcmd = dbcon.CreateCommand()) {
dbcmd.CommandText = script;
dbcmd.ExecuteNonQuery();
}
}
}
}
}

It’s quite useful. Essentially this class loads a SQL script file whose name is the same of the test class, and execute it.
In this way you have for example a TestFeature.cs file alongside a TestFeature.sql file. Nice if your IDE shows files sorted alphabetically.
I found that the best place to use the class is inside the SetUp marked method. In this way the SQL script is run before each test. Doing it in a local development environment is not so bad, since the scripts are executed at high speed.

So, this is an example of how a test that uses TestDbSetup looks like.

using System;
using NUnit.Framework;
using log4net;
using log4net.Config;
namespace TellItMailer {
[TestFixture()]
public class IntegrationTest {
[SetUp]
public void SetUp(){
new TestDbSetup().SetUpDbForTest(this);
}
[Test]
public void TestCase(){
BasicConfigurator.Configure();
}
}
}

Pretty useful, IMHO.

Obtain the root logger programmatically in log4net

danidemi — Mon, 08 Mar 2010 11:15:35 +0000

If you use log4net, you could have the need to configure the loggers programamtically. The problem arise when you want access to the root logger, since the documentation does not explain well how to obtain it.
So, here’s a snippet that show how to do it. Don’t forget to imort the log4net namespaces.

using log4net;
using log4net.Core;
using log4net.Appender;
using log4net.Layout;
using log4net.Repository.Hierarchy;
using log4net.Config;

Hierarchy h = (Hierarchy)log4net.LogManager.GetRepository();
Logger rootLogger = h.Root;

SSH Cheat Sheet

danidemi — Fri, 19 Feb 2010 11:39:00 +0000

Task: login to remote host with username and password

ssh -l [login] -p [port]

Task: login to remote host using a configured alias

First of all you need to configure the alias. The SSH configuration file is normlly stored in ~/.ssh/config. This is an example.

host

Hostname [hostname]
Port [port]
ForwardAgent [yes|no]
ForwardX11 [yes|no]
User [login]

Once you have an alias, you can specify the alias name instead of specify all the options as parameters.

ssh [alias]

Task: login to remote host using key authentication

Put your private key in ~/.ssh/id_rsa
Ensure nobody can access it. After all it’s your private key.
Transfer your public key in your remote host home directory
On the remote host append the public key to the list of authorized ones with the following command.
cat [public_key_file] >> ~/.ssh/authorized_keys
Pay attention to the fact that the authorized_key file should be writeable only by the owner. If you forget that, the key based authentication will definitely fail.

Task: copy a local file to a remote host

Copying file to host:

scp [local_file] [remote_user]@[remote_host]:[path]

Copy the local file “readme.txt” on your remote host folder (don’t forget the “~”) using the “john” username. Let’s suppose the remote host is called “wonderland.org”.

scp readme.txt john@wonderland.org:~

Copying file from host:

scp scp [remote_user]@[remote_host]:[remote_file_path][local_file_path]

Blogged with the Flock Browser

First Facebook application

danidemi — Thu, 28 Jan 2010 17:04:42 +0000

My first Facebook application “Car Pooling”, developed at Tmind, is currently on line and available to you all. Just browse to the following link http://apps.facebook.com/car_pooling/. I hope you’ll enjoy it. And if you have a comment, please let me know!