Author Archives: dmitriano

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29
08
13
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Monitoring CPU Steal Time with command line in Ubuntu

Posted by | Ubuntu | Tagged |

Bash command that writes CPU Steal Time along with other CPU usage statistics from top command header once in a second to MySQL database:

top -b -d 1 | ts ‘%Y-%m-%d %H:%M:%S’ | sed -rn “s/(.{19} )Cpu\(s\):\s+([0-9]+\.[0-9]+)%us,\s+([0-9]+\.[0-9]+)%sy,\s+([0-9]+\.[0-9]+)%ni,\s+([0-9]+\.[0-9]+)%id,\s+([0-9]+\.[0-9]+)%wa,\s+([0-9]+\.[0-9]+)%hi,\s+([0-9]+\.[0-9]+)%si,\s+([0-9]+\.[0-9]+)%st(.*)/INSERT INTO m_perf_stat (CDate, cpu_us,  cpu_sy,  cpu_ni, cpu_id,  cpu_wa,  cpu_hi,  cpu_si,  cpu_st) VALUES (‘\1′, \2, \3, \4, \5, \6, \7, \8, \9);/p” | mysql -u <username> -p<password> <database>

that’s the longest bash command I ever written in my life Улыбка

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15
08
13
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Configuring Firewall to enable FTP, SSH and HTTP on Ubuntu

Posted by | Ubuntu |

FirewallCheck your currently implemented firewall rules with the following command:

iptables -L

Examine the output. On a clean Ubuntu installation you will see an empty ruleset:

Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

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21
07
13
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How to encrypt swap on Ubuntu 12.04

Posted by | Ubuntu |

Without going into particulars, it suffices to say that Ubuntu 12.04 has the following script that sets up encrypted swap:

ecryptfs-setup-swap

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16
06
13
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How to debug a PHP script

Posted by | PHP |

It could be useful sometimes to know what variables are defined at particular point of PHP script in order to have a better understanding of the code you are debugging. In contrast with C++, PHP has a magic function get_defined_vars ( void ) that  returns an array of all defined variables with their values so we can output all variable names with the following line of code:

print_r(array_keys(get_defined_vars()));

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28
05
13
 1 Comment

How to start Apache OFBiz demo under Ubuntu Server 12.04

Posted by | Ubuntu |

Install JDK 6 with the following command:

apt-get install default-jdk

Download the latest OFBiz version, extract it in your home directory and do the following steps described in the README file.

Having apache-ofbiz-XX.XX.XX as the current directory execute the following command:

./ant load-demo

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18
05
13
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How to install Apache Tomcat 7 on Ubuntu Server 12.4 LTS

Posted by | Ubuntu |

Today I successfully installed Tomcat 7 on Ubuntu Server 12.4 LTS with the following commands (executed as root):

apt-get install default-jdk
apt-get install tomcat7
apt-get install tomcat7-admin
apt-get install tomcat7-examples

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13
04
13
 14 Comments

Basic Git commands

Posted by | Ubuntu | Tagged |

Git installs as a normal package on Ubuntu:

sudo apt-get install git

Configuring Git user is an optional step:

git config --global user.email "you@example.com"
git config --global user.name "Your Name"

Type the following command to create an empty repository wherever your code is:

cd ~
git init

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08
04
13
 4 Comments

How to compile BOOST with MS Visual Studio 2010-2017

Posted by | C++ | Tagged , |

Fortunately, to compile BOOST with MS VC 2010 we need Visual Studio Command Prompt and five commands:

Navigate to BOOST directory, for example:

F:
cd F:\Projects\Lib\boost_1_53_0

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12
01
13
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How to pass a Dictionary<Key, Value> from C# to PHP

Posted by | C#, PHP | Tagged , |

I believe that the simplest way to pass complex data from C# to PHP is through WCF service. See my previous post How to implement WCF service in PHP for more details.

Let assume we have a WCF service contract that has the following method with some nested dictionary as a parameter:

[ServiceContract]
public interface IStore
{
    [OperationContract]
    void UpdateRows(Dictionary<int, Dictionary<string, object>> rows);
}

Below I provided the sample implementation of UpdateRows in PHP that iterates through nested dictionaries (first level called ‘rows’ and second level called ‘properties’):

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10
01
13
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WPF TreeView does not support Data Virtualization

Posted by | .NET | Tagged |

WPF implements UI Virtualization via VirtualizingStackPanel and it works great, but situation with Data Virtualization is a bit more complex.

After doing some experimentation I realized that VirtualizingStackPanel when used with WPF TreeView does not allow the data to be virtualized because it iterates through all the collection of data items from inside its MeasureOverride function. However, it access only visible data items when used with DataGrid or ListView, so it allows to use some paging or caching techniques in this case. See the following articles for more information:

If you interested on what I tried to do with TreeView, please read below.

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