Tag Archives: raspberry pi computing

R Tutorials

How to Install the Latest Version of R Statistics on Your Raspberry Pi

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R for Beginners:  How to Install the Latest Version of R Statistics on Your Raspberry Pi

A tutorial by D. M. Wiig

One of the nice characteristics of open source software such as R is the rapid development of new releases and updates.  While the base core remains stable for a period of time there is a considerable amount of updating,  adding, and removing the component packages.  At the time of this writing the latest iteration is R version 3.3.1, “Bug in Your Hair.” If you are using a Windows platform you will likely go directly to the archive web site and download the latest distribution as a Windows executable installation package.

If you are using a Linux distribution  such as Ubuntu or Debian, the process of adding software is usually accomplished via the menu based installer.  These software installers allow  R and its dependencies to be downloaded from the community archive.

One of the disadvantages of using this approach is that the versions of some software in the community archives may not be updated to the latest version.  This is often the case with R as well as with many other software packages.

To insure that you are downloading the latest R version you need to use the platform’s command line to install what is needed.  You can add the URL’s of some backport archives that are more likely to be kept up to date with current releases.  As an example In this tutorial I will use the R statistical software that I am running on my Raspberry Pi 3 board with a Raspbian OS and the new PIXEL desktop.

Regardless of which Linux distribution you are using first open a command console from the desktop menu. Make sure all is up to date by using the command:

pi@raspberrypi:~ $ sudo apt-get update
This will insure all appropriate packages currently installed are running the latest updates.  If you are running a Raspbian distribution such as jessie you will need to edit the /etc/apt/sources.list file to add a backport to the latest version of R.  Start the nano editor by using the command:

sudo nano /etc/apt/sources.list

This should produce the output as seen below:

pi@raspberrypi:~ $ sudo nano /etc/apt/sources.list

------------------------------------------------
GNU nano 2.2.6 File: /etc/apt/sources.list

deb http://mirrordirector.raspbian.org/raspbian/ jessie main contrib non-free r$
# Uncomment line below then 'apt-get update' to enable 'apt-get source'
deb-src http://archive.raspbian.org/raspbian/ jessie main contrib non-free rpi
deb http://archive.raspbian.org/raspbian/ stretch main
deb http://mirror.las.iastate.edu/CRAN/bin/linux/debian/ jessie main
deb http://mirror.las.iastate.edu/CRAN/bin/linux/ubuntu xenial/

[ Read 8 lines ]
^G Get Help ^O WriteOut ^R Read File ^Y Prev Page ^K Cut Text ^C Cur Pos
^X Exit ^J Justify ^W Where Is ^V Next Page ^U UnCut Text^T To Spell

As is seen above there are several lines containing the standard  Raspbian archives to search.

If you are using a Debian distribution you would add the following line to the file:

http://mirror.las.iastate.edu/CRAN/bin/linux/debian/ jessie main

Replace the 'jessie' portion with the name of the specific Debian distribution you are using replace the 'mirror' portion with the R CRAN mirror that you use.  You also need to add the line that provides the URL of a Raspian 'stretch' archive that contains the most recent updates of many different software packages.  In my case I was looking for the latest R release, but you should search this this archive for the latest version of any software package you are installing.

If you are using an Ubuntu distribution add a line with the appropriate changes for the specific Ubuntu distribution that you are using. 
Check with the documentation provided with your specific Linux distribution to see if there is also a 'stretch' archive maintained for new versions. 

Once these changes are made exit the nano editor using the ^O key command to write the file and then the ^X key command to return to the command line.  You should now be able to issue the command:

pi@raspberrypi:~ $ sudo apt-get install r-base r-base-core r-base-dev

Once the download and install processes have completed you should now be able to invoke R from the command line or menu and see the latest version:

pi@raspberrypi:~ $ R

R version 3.3.2 RC (2016-10-23 r71578) -- "Sincere Pumpkin Patch"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: arm-unknown-linux-gnueabihf (32-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

 Natural language support but running in an English locale

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> 


For other Linux distributions you would add a line similar to the above examples in the /etc/apt/sources.list. Check the documentation for your specific Linux platform for further information about backport archives.
Raspberrypi Computing

How to Set Up SSH to Remotely Control Your Raspberry Pi

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Connecting your RPi to the outside world: how to connect remotely via the web

A tutorial by D.M. Wiig

Once you have your RPi server up and running there are a few things that you may want to consider if
you are planning to host content to be delivered over the web. Assuming you have successfully connected your
RPi to the outside world, you can save some processing over head by disconnecting the monitor, keyboard and mouse.
You can access your RPi via the web from another computer using the ssh function for Linux systems and a program such
as PuTTY for Windows systems.

To use access your RPi remotely you must first make sure that ssh is enabled on your Pi. You can do this by opening
a terminal on the Pi and issuing the command:

 

$pi@raspberrypi / $ sudo raspi-config

This will invoke the Raspberry Pi Software Configuation Tool. Select option #8, Advanced Options, and then option

A4 SSH Enable/Disable remote command line access to your Pi using SSH

press enter and take the Enable option from the next menu.

If ssh has not been enabled previously reboot your Pi so that the option will be enabled. You should now be able to access your Pi remotely from any computer connected to the web.

If you are using a linux based computer open a terminal program. The following screen shot shows a typical sequence of commands will access your Pi via the web:
—————————-
doug@doug-Satellite-M55:~$ ssh http://www.raspberrypiandr.net -l pi
pi@www.raspberrypiandr.net’s password:
Linux raspberrypi 3.10.25+ #622 PREEMPT Fri Jan 3 18:41:00 GMT 2014 armv6l

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Tue Mar 25 21:08:54 2014 from 71-34-171-204.desm.qwest.net
pi@raspberrypi ~ $
——————————–
Substitute your URL after the ssh command. After the -l option use whatever you named your Pi when you initially set it up.
You will asked for a password and should then be logged in and see a command line prompt.

If you are using a Windows based computer system you can one of several free programs that will allow you to remotely access your RPi. One of the most popular is called PuTTY. This program can be downloaded from the web site http://www.putty.org. Once you are sure your
remote connect works correctly you can unplug the monitor, keyboard, and mouse from your Pi, leaving just the power connection and whatever type of internet connection you are using. This will help to cut some of the load from your Pi as it functions serving web pages. To end
your remote session simply type ‘logout’ at the command line and you should see something similar to:

——————————–
pi@raspberrypi ~ $ logout
Connection to http://www.raspberrypiandr.net closed.
doug@doug-Satellite-M55:~$
——————————–

You can now close your terminal program until your next remote session.

 

Raspberrypi Computing

How to Install PHP-APC On Your Raspberry PI to speed up your Apache Server

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How to Install PHP-APC on your RPi to speed up your Apache Server

A Tutorial by D.M. Wiig

In a previous tutorial I discuss how to install a LAMP stack on your RPi and set it up as a web server. I have been hosting this WordPress site on my RPi now for serveral months. It has been running quietly and with low power drain 24/7 with virtually no down time. I have a fair amount of content on the site and it has been averaging around 50 or more visits per day since I got it up and running.

While the RPi is not going to have the speed of a professional grade server it does a credible job in applications where the load is reasonable and spread out evenly over the day. There are numerous tips and tricks to fine tune the Apache server that runs in the LAMP stack. One of the most effective and quickest tuneups is to install the program PHP-APC which is an alternative caching program for PHP files. WordPress serves up its content dynamically using PHP so having an efficient caching system for PHP will speed up serving content.

To install PHP-APC on an RPi running the Debian Wheezy Raspian OS open a terminal screen and issue the following command from the command prompt:

pi@raspberrypi / $ sudo apt-get install php-apc
The application will download and install. When the install is complete locate the file “20-apc.ini” The file should be installed in the /etc/php5/conf.d directory. Open the file in the nano editor with the commands:

 

pi@raspberrypi / $ cd /etc/php5/conf.d
pi@raspberrypi /etc/php5/conf.d $ sudo nano 20-apc.ini
The file will open in the editor and should see the following lines:
———————————————————————-
GNU nano 2.2.6 File: 20-apc.ini

extension=apc.so
apc.enabled=1
apc.shm_size=12M
apachectl restart
———————————————————————-

Change the setting apc.sh_size=12M to a larger size such as 20M or so to start. Depending on your needs the size of the cache can be expanded as needed. Press Ctrl-o to save the file and Ctrl-x to exit back to the command prompt. Restart the server with the command:

pi@raspberrypi / $ sudo  apachectl restart

Your Apache server should now be up and running with a larger and faster cache. I do not have any benchmarks to cite, but my WordPress application seems to respond noticeably faster with the apc cache installed. There are many other methods to fine tune your RPi as a web server including installing several alternatives to the Apache server. These are the subject of future tutorials.

 

Raspberrypi Computing

How To: Installing an FTP server on your Raspberry Pi

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How To: Installing an FTP server on your Raspberry Pi

(Author: D.M. Wiig. Your comments and questions are welcomed.)

If you are running any of the Linux distributions on your Rpi it is a fairly simple process to install a basic FTP server. There are a number of very good FTP servers available for Linux with vsftpd being one of the most popular. This tutorial will discuss the specifics of a vsftpd server installation. The process would be very similar for other popular FTP servers.

For the sake of simplicity this tutorial will only cover the basic installation of vsftpd for anonymous mode. This means that any user can access the ftp server and download files without a login procedure. By default vsftpd is configured to allow anonymous access and download only. A future tutorial will discuss the setting of options for authentication mode and other client services.

To install vsftpd login to your Rpi and at the command prompt enter:

$ sudo apt-get install vsftpd

When the installation is complete you will see the line:

Starting FTP server: vsftpd

By default a directory for ftp users is created with a home directory of /srv/ftp. This is the default ftp directory. You can check to make sure the ftp server is up and running properly by doing the following:

From the command line issue the command:

$ cd /srv/ftp

Once you are in the ftp directory create a test file by using the following commands:

$ sudo nano ftpsamplefile

Nano is a fast and simple text editor for Raspian. When opened you will get a blank screen. Type in something like:

This is a sample file file loaded in the default ftp directory

/srv/ftp

4/1/14

After you have entered the text hit press Ctrl-o to save the file you have created and then Ctrl-x to exit nano after the line has been saved. Enter the following command in your Rpi to determine the local address of the Rpi:

sudo ifconfig

You will see a number of lines of information. One of the top lines should contain something like:

inet addr:192.xxx.x.xx

This sequence of numbers is the local network address of your Rpi. You can ftp to it from any device on your network, but at this point you are not connected to the outside world so you cannot connect to it from outside of your router and network without some additional steps. To test your installation, open a web browser on any device that you have connected to the same network as your Rpi and enter:

ftp://192.xxx.x.xx (substitute your address found with the ifconfig command for the x’s)

You should see the ftp user directory that will look something like the example below:

Index of /

Name

Size

Date Modified

ftpsamplefile

69 B

3/31/13 8:05:00 PM

The ftp folder will contain the sample file that you created previously. By clicking on the file you should see the contents:

This is a sample ftp file loaded in the directory

/srv/ftp

Your FTP server is now up and running. I will cover issues such as file upload and download as well as creating user authentication and login procedures in another ‘How To:’

 

Raspberrypi Computing

How To Connect Your Raspberry Pi Server to the Outside World

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How To Connect Your Raspberry Pi Server to the Outside World

A tutorial by D.M. W

 

Once you have your server set up and running you need to make some changes to your home network to allow the Pi to connect to the outside world. A typical home network consists of an Web connection to a router through which local devices are connected. You can usually connect to your router by using your browser to connect to http://192.168.0.1 or something similar. This is the local address of the router and will give you a number of menu options for changing router settings and getting router information.

All devices connected to the router will have addresses that are similar to 192.xxx.x.xx. You can determine the local address of your Pi by looking at the ‘Device Table’ information in your router or by opening up a command line terminal interface and entering the command:

pi@raspberrypi ~ $ sudo ifconfig

eth0 Link encap:Ethernet HWaddr b8:27:eb:be:3f:bd

inet addr:192.168.0.27 Bcast:192.168.0.255 Mask:255.255.255.0

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:15804 errors:0 dropped:0 overruns:0 frame:0

TX packets:5686 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:1205858 (1.1 MiB) TX bytes:2103034 (2.0 MiB)

lo Link encap:Local Loopback

inet addr:127.0.0.1 Mask:255.0.0.0

UP LOOPBACK RUNNING MTU:65536 Metric:1

RX packets:356 errors:0 dropped:0 overruns:0 frame:0

TX packets:356 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:0

RX bytes:27968 (27.3 KiB) TX bytes:27968 (27.3 KiB)

I have added the highlighting to show the local address of my Pi. Yours should be similar. Normally all devices connected to the local network can send input and output to the web through the router but are behind a firewall and cannot be accessed directly from the web. In order to use your Pi as a server you need to provide a path through the firewall so that it can be accessed from the web. This is done on most routers by using the ‘Port Forwarding’ feature that is available. Most servers including the Pi ‘listen’ for connect requests on port 80. You can use the port forwarding setting on you router to connect the local address of your Pi to port 80 on the router. On my router the table looks like this:

Connection Status:

CenturyLink®Broadband

2272/864 Kbps

ISP Status:

Port ForwardingEnter ports or port ranges required to forward Internet applications to a LAN device below.

1. Enter the LAN port and IP information.

  Starting Port:

  Ending Port:

  Protocol:

  LAN IP Address:

2. Enter the remote port and IP information. (Optional)

  Starting Port:

  Ending Port:

  Remote IP Address:

 Use 0.0.0.0 for any IP Address

3. Click “Apply” to save your settings.

 

Port Forwarding List

    

LAN Ports

Protocol

LAN IP
Address

Remote Ports

Remote IP
Address

Edit

80 – 80

TCP

192.168.0.27

N/A

N/A

21 – 21

TCP

192.168.0.27

N/A

N/A

22 – 22

TCP

192.168.0.27

N/A

N/A

As you can see I have several ports connected to the Pi. Port 21 is commonly used for FTP access and port 22 for ssh access. These are topics for future postings.

Please not that the 198.xxx.x.xx address is a local address and not the address that your router uses to connect to your ISP. The ISP address can be found in the router general information and status tables. If your Pi is set up correctly you should be able to connect to the Pi server from any device connected to the internet by enteringthe URL http://xxx.xx.xx.x (your router’s ISP web address) in a browser. You should see the default apache web page:

It works!

This is the default web page for this server.

The web server software is running but no content has been added, yet.

More to Come: