The upgrade from Raspbian Wheezy to Raspbian 8 Jessie is a fairly simple procedure. However, a caution must be exercised as there is always a chance to break the entire system. The less packages and services are installed the more likely you will be able successfully upgrade your Raspbian Linux system.

Recommendations:

• Remove unnecessary packages
• Fully upgrade your current system
• Make a data backup
• Although there should not be a problem to perform update via SSH it is recommended to perform upgrade directly using console

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Sometimes you may need to reset your Wordpress password directory by updating a password filed of your wordpress wp_users table. The required password needs to a salted MD5 string. The easiest way to generate a Wordpress hash password from a plain test is to use openssl.

For example let’s create a new Wordpress hash password string from a plain text such as wordpress_pass:

$ openssl passwd -1 'wordpress_pass'
$1$ldalRXj4$wOZp2NjBYsn0UosVKj68N0

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Project name: IPwatchD – IP conflict detection tool
Author: Jaroslav Imrich
Project’s Home Page: IPwatchD

Introduction

When using a GNU/Linux operating system, from time to time you may come across a situation where network connectivity was interrupted due to the IP conflict. An IP conflict event occurs when two or more hosts on the same network are configured with identical IP addresses. At the present, there appears to be no code in the Linux kernel to take care of this situation by means of appropriate Gratuitous ARP response . Very often a network administrator is left in the complete ignorance by the Linux kernel and needs to troubleshoot IP conflict the hard way. Fortunately, there is a simple daemon called IPwatchD which main purpose is to catch and evaluate packets on the network and this way is able to prevent an IP conflict occurrence. This is done by help of libpcap library. IPwatchD daemon is written in C language and can run in passive or active modes. The difference between a passive and active mode is that in the passive mode IPwatchD only logs every IP conflict event by engaging syslog daemon, and in active mode IPwatchD takes one step further and responds to Gratuitous ARP request which is the main construction block when it comes to the IP conflict prevention. This article will explore this simple daemon in terms of installation, configuration and usage.

Prerequisites

Before we can install IPwatchD under the GNU/Linux operating system it is recommended to confirm that all prerequisites needed by IPwatchD are installed on the system. Here is a list of packages you would need to install on Ubuntu 8.10.

 * build-essential - C compiler and other development tools
  * libpcap-dev     - Network packet capture library
  * libnet1-dev     - Network packet construction library
  * libnotify-dev   - sends desktop notifications to a notification daemon 

On ubuntu or debian linux you can install those packages with a following linux command:

# apt-get install build-essential libpcap-dev libnet1-dev libnotify-dev 

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In this config you will learn how to block or redirect web traffic based on the visitor’s country geographical location using Apache’s geoip mod.

Apache mod_geoip installation

Assuming that you already have Apache webserver installed and running we start by the installation of mod_geoip:

UBUNTU/DEBIAN
# apt-get install libapache2-mod-geoip
CENTOS/REDHAT/FEDORA ( epel enabled only )
# yum install mod_geoip.x86_64

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The following linux commands will help you to obtain the information about your laptop battery such as manufacturer, part type, capacity, voltage etc. First, tool which can be used for this job is dmidecode command. If you currently do not have dmidecode available on your Linux system you can install it by:

UBUNTU/DEBIAN
# apt-get install dmidecode
CENTOS/FEDORA
# yum install dmidecode

next, using dmidecode we can obtain some hardware information about our battery:

# dmidecode -t 22
# dmidecode 2.12
SMBIOS 2.6 present.

Handle 0x002E, DMI type 22, 26 bytes
Portable Battery
        Location: Rear
        Manufacturer: LGC
        Name: 42T4942
        Design Capacity: 93240 mWh
        Design Voltage: 11100 mV
        SBDS Version: 03.01
        Maximum Error: Unknown
        SBDS Serial Number: 073C
        SBDS Manufacture Date: 2012-03-23
        SBDS Chemistry: LION
        OEM-specific Information: 0x00000000

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Using an ENTRYPOINT Docker command specified within a Dockerfile one can pass an arguments to an interactive Docker container upon its launch. Consider a following Dockerfile content:

FROM debian:8
ENTRYPOINT ["echo"]

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Questions:
How can I remove all docker containers based on a docker image name. I do not wish to remove all available containers, only the those which are based on particular image. For example I would like to remove all containers based on image centos:7.

Answer:
To remove all docker containers based on centos:7 run the following linux command:

# docker ps -a | awk '{ print $1,$2 }' | grep centos:7 | awk '{print $1 }' | xargs -I {} docker rm {}

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