Install operating system on raspberry pi and play with LED on/off

Hi Readers,

Hope all are doing well,

I am going to talk about raspberry pi.

What is raspberry pi –

The Raspberry Pi is a series of small single-board computers developed in the United Kingdom by the Raspberry Pi Foundation to promote the teaching of basic computer science in schools and in developing countries.

A Raspberry Pi is a credit card-sized computer originally designed for education, inspired by the 1981 BBC Micro. Creator Eben Upton’s goal was to create a low-cost device that would improve programming skills and hardware understanding at the pre-university level. But thanks to its small size and accessible price, it was quickly adopted by tinkerers, makers, and electronics enthusiasts for projects that require more than a basic microcontroller (such as Arduino devices).

The Raspberry Pi is slower than a modern laptop or desktop but is still a complete Linux computer and can provide all the expected abilities that implies, at a low-power consumption level.

 

Need – sd card, card reader, monitor

Insrer sd card in card reader and connect cardreader to computer/laptop

fire command df –

check where your sd card is inserted

you need fire umount command from path where it’s mounted..NOTE- to format any device we need to unmount it first

like you need to umount /dev/mmcblk0px(x is any number) and path of /dev/mmcblk0px (x ia any number ) is /run/media/anandprakashdnyaneshwartandale/SETTINGS

then you need to fire command-

umount /run/media/anandprakashdnyaneshwartandale/root  and

umount /run/media/anandprakashdnyaneshwartandale/SETTINGS

after fireing lsblk command you should be able to see –  ‘mmcblk0’ path

like-

mmcblk0 179:0 0 29.7G 0 disk
├─mmcblk0p2 179:2 0 1K 0 part
├─mmcblk0p7 179:7 0 28.5G 0 part
├─mmcblk0p5 179:5 0 32M 0 part
├─mmcblk0p1 179:1 0 1.1G 0 part
└─mmcblk0p6 179:6 0 63M 0 part

 

After that you need to fire a command  sudo mkdosfs -F 32 -v /dev/mmcblk0 to install format the device(sd card here)

sudo dd bs=1M if=”path to image” of=/dev/mmcblk0 status=progress

 

 

 

fire command sudo mkdosfs -F 32 -v /dev/mmcblk0  – to format your file system

if you are using fedora your path of sd card will be something like /dev/x/x/

if you are using ubuntu then path would be /media/x/x

I will talk about fedora,

so after formatting,  you nned to install something onm that right?

so fire the command ‘sudo dd bs=1M if=”path/of/image/for/raspberrypi” of=/dev/mmcblk0 status=progress’

dd is use to convert and copy a file, you can see man pages of dd

then go to you sd card by cd command – in my case ‘cd /run/media/anandprakashdnyaneshwartandale/46ed1fb6-8b80-414d-b41a-e721d2b37b05’

there you can see filesytem etc,mnt,var,usr etc

go to etc of your sd card and append your internet connection in /network/interfaces fire

to make your raspberrypi system accessible by ssh, you need to make ssh enabled by adding following line in etc/rc.local (NOTE- etc is inside of raspberrypi system not your local)

IP=$(hostname -I) || true
if [ “$_IP” ]; then
printf “My IP address is %s\n” “$_IP”
fi

if [ -e /etc/SSHFLAG ]; then

/usr/sbin/update-rc.d -f ssh defaults

/bin/rm /etc/SSHFLAG

/sbin/shutdown -r now

fi

sudo /etc/init.d/ssh start

 

Then  you need to check ip address of sytem mounted on sd card – how?

ans- just remove sd card reader , insert sd card in raspberry pi connect raspberry pi to any monitor and reoot it, if network is good you can see ip address of system installed on sd card in rasberrypi

you need to copy that ip.

now you rasberry pi is on-

and steps to get gui of raspberrypi sytem using tightvnc and vncviwer

open xterm on your system, enter ‘vncviewer’ command on xterm

then you will see pop up asking for ip address and port to connect using vncviewer

enter ip address of you raspberrypi and enter port it’s listening try port 1/2 as well

then you wiil get gui of sytem install on sd inserted in raspberrypi

you can ssh using ssh pi@ipaddressfound and password is raspberrypi

after successful of ssh you need to require packages related to python on that

i just fired command ‘apt-get install python-dev’

commect LED and  to pins of raspberrypi like-

 

 

then fire command python3 on the seesion where you ssh to system installed on sd card inserted in raspberrypi

from RPi import GPIO as io

io.setmode(io.BOARD)

io.setup(16, io.OUT) – to get output from raspberry pi

io.output(16, io.LOW) – to turn off LED

io.output(16, io.HIGH) – to turn on LED

yeahhhhhhhhhhhhhhh, ver long blog but very interesting right?

so now you can do python programs to do ehatever you want to do with LED may be blinking design with many LEDS. so go for it, all the best.

 

 

 

‘Django – python web framework’ session taken by me in Python Pune Meetup Feb 2017

Hi Readers,

On 26th Feb, I took a session on ‘django – python web framework’ in Python Pune Meetup at Tixdo Pvt. Ltd. Cybercity, magarpatta Pune.

I gave a demo as well, but now, I am pasting content of my slides.

slide 1 – django

Web framework written in python
MTV – Model(data access), Template(presentation), View(bridge between M and T / logic)
Request response
Fast, secure, scalable, opensource.

 

slide 2 – architecture

 

slide 3-

The developer writes/provides the model and then template and view maps to the url

slide 4 –

Django comes with a lightweight web server for developing and testing applications. This server is pre-configured to work with Django.

slide 5-  Installation

Prerequisites – python
dnf install python-django
git clone git://github.com/django/django.git , pip install -e django/
Install pip/pip3 and then pip/pip3 install django
using virtualenv

 

slide 6 – Imp files in django after creation of project/app

manage.py
settings.py
urls.py
views.py
wsgi.py

 

slide 7 –  important links

http://djangobook.com/https://www.djangoproject.com/https://developer.fedoraproject.org/https://www.tutorialspoint.com/django/

 

 

Popular database now a days – REDIS

Hi readers,

 

Now a days redies database is very famous.

Because it is in memory database. in memory databases are the databases who used main memory to store the data they dont have storage management system/engine like mysql.

Redis is nosql database, you can store your data in hash/key-value pair format.

It is very fasr so many big companies like twitter instagram, github, stackoverflow are using redis.

We have opensource redis and enterprise redis (redis labs).

 

I will keep posting more information about redis in coming blogs.

What is Kubernetes

Hi readers,

I already published blog about Docker and difference between docker and virtual machine.

Imagine you want to deploy docker on many servers and manage those servers by automation. Kubernetes is the solution for that.

What is Kubernetes-

Kubernetes is basically tool or system which manages deployment, scaling, performing operations of containers like docker automatically over the cluster.

Cluster is basically group of servers.

With Kubernetes, you are able to quickly and efficiently respond to customer demand:

best practices to work around kubernetes go through http://containertutorials.com/get_started_kubernetes/index.html

you want to understand components of kubernetes go through https://kubernetes.io/docs/admin/cluster-components/

Docker vs Virtual Machine

Hi readers,

I have already published 1 blog regarding docker.

Today I am going to tell you difference between Docker and Viertual Machine(VM)

The main difference between docker and vm is their architecture.

In vm hypervisor plays very important role.

On top of hardware level it have hypervisor.

Hypervisor distributes the guest os and however os are there we can have that much applications. With each different os we have different kernels.

But in case of docker-

Lxc plays very imp role.

Lxc is basically linux container, is an operating-system-level virtualization method for running multiple isolated Linux systems (containers) on a control host using a single Linux kernel. (in vm concepts we should have different kernel for different os, this is main imp difference)

 

Lxc is an operating-system-level virtualization method for running multiple isolated Linux systems (containers) on a control host using a single Linux kernel.

The Linux kernel provides the cgroups functionality that allows limitation and prioritization of resources (CPU, memory, block I/O, network, etc.) without the need for starting any virtual machines, and also namespace isolation functionality that allows complete isolation of an applications’ view of the operating environment, including process trees, networking, user IDs and mounted file systems.^[3]

LXC combines the kernel’s cgroups and support for isolated namespaces to provide an isolated environment for applications. Docker can also use LXC as one of its execution drivers, enabling image management and providing deployment services.

 

 

Useful networking linux commands

Hi readers,

I have talking about cloud, OpenStack for this block readers.

To earn more knowledge about cloud and OpenStack you have to have good knowledge of networking.

Following are the basic networking commands for the linux which you must aware about.

 

ifconfig –

fconfig (interface configurator) command is use to initialize an interface, assign IP Address to interface and enable or disable interface on demand. With this command you can view IP Address and Hardware / MAC address assign to interface and also MTU (Maximum transmission unit) size.

 

ifconfig interface –

e.g.  ifconfig eth0 –

fconfig with interface (eth0) command only shows specific interface details like IP Address, MAC Address etc. with -a options will display all available interface details if it is disable also.

 

ping ip address/url –

e.g. ping google.com or ping x.x.x.x –

PING (Packet INternet Groper) command is the best way to test connectivity between two nodes. Whether it is Local Area Network (LAN) or Wide Area Network (WAN). Ping use ICMP (Internet Control Message Protocol) to communicate to other devices

 

traceroute-

e.g. traceroute ip address

traceroute is a network troubleshooting utility which shows number of hops taken to reach destination also determine packets traveling path. Below we are tracing route to global DNS server IP Address and able to reach destination also shows path of that packet is traveling.

 

netstat-

e.g. netstat -tnlp

It is very imp command to check your desired port listing desire services.

Netstat (Network Statistic) command display connection info, routing table information etc. To displays routing table information use option as -r.

 

dig-

e.g.- dig http://www.google.com

Dig (domain information groper) query DNS related information like A Record, CNAME, MX Record etc. This command mainly use to troubleshoot DNS related query.

 

route-

e.g-

route

route command also shows and manipulate ip routing table. To see default routing table in Linux, type the following command.

 

 

 

what is cloud computing in simple words

Hi readers,

Many people talk about cloud computing in detail like virtualization,storage, but very few are able to explain ‘term’ in basic simple words.

Reader of this blog will understand the basic but important concept of cloud computing.

 

What is Cloud Computing-

It is a type of computing groups of remote servers and

software networks that allow centralized data storage and

online access to computer services or resources.

Using cloud computing we can manipulate,configure and

access the applications online.

Delivery of on-demand computing resources.

what is opensource and it’s Importance

Hi readers,

I can see currently there are many people are talking about opensource, opensource -projects,techniques, functionality, usability.

Only few have the perfect knowledge of the word/world of opensource.

The reader of this blog will have the good knowledge of opensource.

So go through this blog and earn great knowldge of opensource.

Open-source

Open source refers to a program or software in which the

source code (the form of the program when a programmer

writes a program in a particular programming language) is

available to the general public for use and/or modification from

its original design free of charge

Open source code is typically created as a collaborative effort

in which programmers improve upon the code and share the

changes within the community

Proprietary software is privately owned and controlled. In the

computer industry, proprietary is considered the opposite of

open. A proprietary design or technique is one that is owned

by a company. It also implies that the company has not

divulged specifications that would allow other companies to

duplicate the product

Why to choose open-source

Control

Training

Security

Stability

You can be famous

Own product/project

Understanding code of standard

Helping the people who can’t affort costly software

Freedom

Support option

Quality

some open-source projects

Mozilla

Chromium

Apache

Ubuntu

Python

OpenOffice

Paint.net

Python

Python is an

some basic but imp in python- dir(datatype/varible)

Hi readers,

I am writing this blog  just to convey you, how python is more efficient even you don’t want remember in built functions of the data structure/variable in python.

Lets say a=[1,2,3,4,5]

a is a dictionary.You want to perform some operation using inbuilt function on this list, but you dont know all the in built function related to list.

So, what the reader of this blog do-

he/she should do dir(a)

and he/she will find the list of all the inbuilt functions.

example-

>>> a=[1,2,3,4,5]
>>> a
[1, 2, 3, 4, 5]
>>> dir(a)
[‘__add__’, ‘__class__’, ‘__contains__’, ‘__delattr__’, ‘__delitem__’, ‘__delslice__’, ‘__doc__’, ‘__eq__’, ‘__format__’, ‘__ge__’, ‘__getattribute__’, ‘__getitem__’, ‘__getslice__’, ‘__gt__’, ‘__hash__’, ‘__iadd__’, ‘__imul__’, ‘__init__’, ‘__iter__’, ‘__le__’, ‘__len__’, ‘__lt__’, ‘__mul__’, ‘__ne__’, ‘__new__’, ‘__reduce__’, ‘__reduce_ex__’, ‘__repr__’, ‘__reversed__’, ‘__rmul__’, ‘__setattr__’, ‘__setitem__’, ‘__setslice__’, ‘__sizeof__’, ‘__str__’, ‘__subclasshook__’, ‘append’, ‘count’, ‘extend’, ‘index’, ‘insert’, ‘pop’, ‘remove’, ‘reverse’, ‘sort’]
>>> dir(list)
[‘__add__’, ‘__class__’, ‘__contains__’, ‘__delattr__’, ‘__delitem__’, ‘__delslice__’, ‘__doc__’, ‘__eq__’, ‘__format__’, ‘__ge__’, ‘__getattribute__’, ‘__getitem__’, ‘__getslice__’, ‘__gt__’, ‘__hash__’, ‘__iadd__’, ‘__imul__’, ‘__init__’, ‘__iter__’, ‘__le__’, ‘__len__’, ‘__lt__’, ‘__mul__’, ‘__ne__’, ‘__new__’, ‘__reduce__’, ‘__reduce_ex__’, ‘__repr__’, ‘__reversed__’, ‘__rmul__’, ‘__setattr__’, ‘__setitem__’, ‘__setslice__’, ‘__sizeof__’, ‘__str__’, ‘__subclasshook__’, ‘append’, ‘count’, ‘extend’, ‘index’, ‘insert’, ‘pop’, ‘remove’, ‘reverse’, ‘sort’]
>>> b=1
>>> dir(b)
[‘__abs__’, ‘__add__’, ‘__and__’, ‘__class__’, ‘__cmp__’, ‘__coerce__’, ‘__delattr__’, ‘__div__’, ‘__divmod__’, ‘__doc__’, ‘__float__’, ‘__floordiv__’, ‘__format__’, ‘__getattribute__’, ‘__getnewargs__’, ‘__hash__’, ‘__hex__’, ‘__index__’, ‘__init__’, ‘__int__’, ‘__invert__’, ‘__long__’, ‘__lshift__’, ‘__mod__’, ‘__mul__’, ‘__neg__’, ‘__new__’, ‘__nonzero__’, ‘__oct__’, ‘__or__’, ‘__pos__’, ‘__pow__’, ‘__radd__’, ‘__rand__’, ‘__rdiv__’, ‘__rdivmod__’, ‘__reduce__’, ‘__reduce_ex__’, ‘__repr__’, ‘__rfloordiv__’, ‘__rlshift__’, ‘__rmod__’, ‘__rmul__’, ‘__ror__’, ‘__rpow__’, ‘__rrshift__’, ‘__rshift__’, ‘__rsub__’, ‘__rtruediv__’, ‘__rxor__’, ‘__setattr__’, ‘__sizeof__’, ‘__str__’, ‘__sub__’, ‘__subclasshook__’, ‘__truediv__’, ‘__trunc__’, ‘__xor__’, ‘bit_length’, ‘conjugate’, ‘denominator’, ‘imag’, ‘numerator’, ‘real’]
>>> dir(int)
[‘__abs__’, ‘__add__’, ‘__and__’, ‘__class__’, ‘__cmp__’, ‘__coerce__’, ‘__delattr__’, ‘__div__’, ‘__divmod__’, ‘__doc__’, ‘__float__’, ‘__floordiv__’, ‘__format__’, ‘__getattribute__’, ‘__getnewargs__’, ‘__hash__’, ‘__hex__’, ‘__index__’, ‘__init__’, ‘__int__’, ‘__invert__’, ‘__long__’, ‘__lshift__’, ‘__mod__’, ‘__mul__’, ‘__neg__’, ‘__new__’, ‘__nonzero__’, ‘__oct__’, ‘__or__’, ‘__pos__’, ‘__pow__’, ‘__radd__’, ‘__rand__’, ‘__rdiv__’, ‘__rdivmod__’, ‘__reduce__’, ‘__reduce_ex__’, ‘__repr__’, ‘__rfloordiv__’, ‘__rlshift__’, ‘__rmod__’, ‘__rmul__’, ‘__ror__’, ‘__rpow__’, ‘__rrshift__’, ‘__rshift__’, ‘__rsub__’, ‘__rtruediv__’, ‘__rxor__’, ‘__setattr__’, ‘__sizeof__’, ‘__str__’, ‘__sub__’, ‘__subclasshook__’, ‘__truediv__’, ‘__trunc__’, ‘__xor__’, ‘bit_length’, ‘conjugate’, ‘denominator’, ‘imag’, ‘numerator’, ‘real’]
>>> c=’string’
>>> dir(c)
[‘__add__’, ‘__class__’, ‘__contains__’, ‘__delattr__’, ‘__doc__’, ‘__eq__’, ‘__format__’, ‘__ge__’, ‘__getattribute__’, ‘__getitem__’, ‘__getnewargs__’, ‘__getslice__’, ‘__gt__’, ‘__hash__’, ‘__init__’, ‘__le__’, ‘__len__’, ‘__lt__’, ‘__mod__’, ‘__mul__’, ‘__ne__’, ‘__new__’, ‘__reduce__’, ‘__reduce_ex__’, ‘__repr__’, ‘__rmod__’, ‘__rmul__’, ‘__setattr__’, ‘__sizeof__’, ‘__str__’, ‘__subclasshook__’, ‘_formatter_field_name_split’, ‘_formatter_parser’, ‘capitalize’, ‘center’, ‘count’, ‘decode’, ‘encode’, ‘endswith’, ‘expandtabs’, ‘find’, ‘format’, ‘index’, ‘isalnum’, ‘isalpha’, ‘isdigit’, ‘islower’, ‘isspace’, ‘istitle’, ‘isupper’, ‘join’, ‘ljust’, ‘lower’, ‘lstrip’, ‘partition’, ‘replace’, ‘rfind’, ‘rindex’, ‘rjust’, ‘rpartition’, ‘rsplit’, ‘rstrip’, ‘split’, ‘splitlines’, ‘startswith’, ‘strip’, ‘swapcase’, ‘title’, ‘translate’, ‘upper’, ‘zfill’]

RethinkDB: the open-source database for the realtime web

RethinkDB is an open source, NoSQL, distributed document-oriented database. It storesJSON documents with dynamic schemas, and is designed to facilitate pushing real-time updates for query results to applications.

 

ReQL is the RethinkDB query language. It offers a very powerful and convenient way to manipulate JSON documents.

 

Instead of polling for changes, the developer can tell RethinkDB to continuously push updated query results in realtime  You can also write applications on top of RethinkDB using traditional query-response paradigm, and subscribe to realtime feeds later as you start adding realtime functionality to your app. offers a much higher level of abstraction. RethinkDB’s feeds integrate seamlessly with the query computation engine, and allow you to subscribe to changes on query results, not just raw replication data. This architecture dramatically reduces the time and effort necessary to build scalable realtime app.

• An advanced query language that supports table joins, subqueries, and massively parallelized distributed computation.
• An elegant and powerful operations and monitoring API that integrates with the query language and makes scaling RethinkDB dramatically easier.
• A simple and beautiful administration UI that lets you shard and replicate in a few clicks, and offers online documentation and query language suggestions.

 

The query-response database access model works well on the web because it maps directly to HTTP’s request-response

 

However, modern applications require sending data directly to the client in realtime. Use cases where companies benefited from RethinkDB’s realtime push architecture 

 

you can also write applications on top of RethinkDB using traditional query-response paradigm, and subscribe to realtime feeds later as you start adding realtime functionality to your app.

 

However, RethinkDB’s query language can do nearly anything SQL can do, including table joins and aggregation functions, and it’s powerful, expressive and easy to learn. ReQL can also do many things SQL can’tdo, including mixing queries with JavaScript expressions and map-reduce.

 

Supports  Client-side triggers through changefeeds.

 

 

When a server fails, it may be because of a network availability issue or something more serious, such as system failure. In a multi-server configuration, where tables have multiple replicas distributed among multiple physical machines, RethinkDB will be able to maintain availability automatically 

 

 

Development support

can see live performance of the cluster using graph on rethinkdb dashboard,able write,view databases easily using dashbaoard.

 

RethinkDB uses three ports to operate—the HTTP web UI port, the client drivers port, and the intracluster traffic port. You can connect the browser to the web UI port to administer the cluster right from your browser, and connect the client drivers to the client driver port to run queries from your application. If you’re running a cluster, different RethinkDB nodes communicate with each other via the intracluster traffic port.

 

 

when to use-

RethinkDB is a great choice when your applications could benefit from realtime feeds to your data.

The query-response database access model works well on the web because it maps directly to HTTP’s request-response. However, modern applications require sending data directly to the client in realtime. Use cases where companies benefited from RethinkDB’s realtime push architecture include

 

 

example-

• Collaborative web and mobile apps

• Streaming analytics apps

• Multiplayer games

• Realtime marketplaces

• Connected devices

port- Once RethinkDB is running, you can connect to it at http://localhost:8080, assuming you’ve kept the default port (8080) and it’s running on your local machine.s

 

 

RethinkDB uses a range sharding algorithm parameterized on the table’s primary key to partition the data. When the user states they want a given table to use a certain number of shards, the system examines the statistics for the table and finds the optimal set of split points to break up the table evenly. All sharding is currently done based on the table’s primary key, and cannot be done based on any other attribute (in RethinkDB the primary key and the shard key are effectively the same thing).