Setting Up Raspberry Pi To Run Bots

Server-web

Where’s the server? It’s under the table next to the couch!

The Raspberry Pi can be used for lots of cool projects, but because it’s cheap, small, and consumes far less power than a regular laptop or desktop, it’s perfect for applications where a computer needs to be running constantly, such as a server for running Twitter bots!

I have seven bots running at the moment, tweeting things like art assignments, “would you rather?” questions, and links from a 1995 “internet directory” book. Most of them post once an hour at varying times during the hour, meaning I need to run them from a computer that is always on, 24/7. I had previously used a Mac Mini, but it felt wasteful to have such a powerful computer that consumed so much energy, just to post 140 characters to Twitter.

By way of comparison, here is the energy use of a 2012 Mac Mini and a Raspberry Pi Model B:

 RASPBERRY PI (MODEL B)MAC MINI (2012)
IDLE2.19W11W
MAX2.64W85W

The Mac Mini also creates a lot of heat, even when not really doing anything. It’s average heat dissipation is 126 BTUs per hour, or the equivalent of 1/3 of a human!

Update: turning off video output (via RCA/HDMI) can save power consumption even more, especially for battery operation. Turn it off using the following command: /opt/vc/bin/tvservice -off, though it may not work on your device.

That’s enough convincing: let’s run some bots!

STEP 0: BASIC SETUP AND THINGS WE NEED

This tutorial assumes you have your Pi set up with an operating system, etc. If you need help with that, there are lots of great tutorials to help you out.

For this tutorial, you will need:

  • A working bot – if you need help writing one, you can see my tutorial!
  • Your Raspberry Pi, plugged into power and ethernet.
  • Your Raspberry Pi’s main username and password. The default username is usually pi (we’ll use this to connect to your Pi via SSH in the Terminal).
  • FTP client such as Filezilla or Transmit (we’ll use this to send files to your Pi remotely).
  • Some experience using the command-line. This tutorial shows Mac screenshots, but should work the same for Linux users; Windows users may need some tweaking to get this to work. If you have any problems or suggestions, please leave them in the comments.

 

STEP 1: HEADLESS MODE

We need the Pi to run without a screen, keyboard or mouse, or any other peripherals, and to accept connections via SSH. This is called running “headless” and is how most servers are configured.

Screen Shot 2014-08-31 at 12.04.36 PM

Screen Shot 2014-08-31 at 12.04.40 PM

Note that this step, and all others below, can be done remotely via SSH once the Pi is set up!

  1. Start up your Pi as usual with a monitor and keyboard connected (this is the last time we’ll need to do this!)
  2. Once the startup completes, don’t start a graphical session. If it is set to launch automatically, you can complete this step in the Terminal (called LXTerminal on many Pi distributions).
  3. Type sudo raspi-config  and enter your password
  4. Scroll down to  ssh  using the arrow keys, then hit  Enter
  5. Select  Enable  and hit  Enter
  6. Exit  raspi-config  by selecting  Finish

Note that some RPi distributions, including the standard Raspian, log in the first time to the graphical OS. You can change this in the raspi-config  menu, accessed via the command line.

 

STEP 2: ENABLE AUTO-LOGIN

We want our Pi to boot and run without asking for a username and password. If the Pi was to crash or have an interruption in power, we want it to restart automatically and start posting again without us having to intervene.

Screen Shot 2014-08-31 at 12.14.12 PM

  1. In the Terminal, type  sudo nano /etc/inittab
  2. This will open the  inittab  file in Nano, a command-line text editor
  3. Look for this line (or something very similar) and put a  #  in front of it to comment it out – it should look like this:
    # 1:2345:respawn:/sbin/getty 115200 tty1
  4. Add a new line below:
    1:2345:respawn:/bin/login -f pi tty1 </dev/tty1 >/devtty1 2>&1
    Note that you should replace  -f pi  with your username if necessary
  5. Hit control-X , then  Y  to save

This step is via this useful guide, if you’d like to read more in depth.

 

STEP 3: CONNECT VIA SSH

Secure Shell (SSH) lets us connect to the Pi via another computer on the same network. With SSH, you can change configurations on your Pi, run maintenance, and most anything else via the command-line on your computer – much easier than finding a monitor cable and spare keyboard!

Screen Shot 2014-08-31 at 12.24.59 PM

You can connect one of two ways:

EASIEST
Log in using your username and the name of your Pi:

  1. From your main computer, type the following into the Terminal:
    ssh pi@rasbperrypi
    Change  pi  to whatever your main username is, if necessary
  2. Enter your password when prompted, then you’re in!
  3. Disconnect by typing exit

HARDER
If the above method doesn’t work, you’ll need to find the IP address of your Pi.

  1. From your main computer, type the following command:
    ping raspberrypi
  2. The result will be an IP address in the form of four numbers separated by commas, such as: 192.xxx.x.x
  3. This may change as new computers join or leave the network, so you will need to run ping each time you want to connect to your Pi. Alternatively, you can set a fixed IP address, but for me it hasn’t been worth the amount of “under the hood” work.
  4. Connect to your Pi by typing ssh xxx.xxx.x.x -l pi , where  xxx.xxx.x.x  is the IP address you found in the previous steps and  pi  is your username
  5. Enter your password when prompted, then you’re in!
  6. Disconnect by typing exit

You can now enter Terminal commands, just like if you had a keyboard and monitor plugged right in! If you don’t use the command-line very much, here’s some useful commands to learn:

  • pwd  to print the current directory path
  • ls  to list the files/directories in the current location
  • cd <folder>  to move into a folder in the current directory – for example, to go to the Desktop from the home folder, type cd Desktop
  • cd ../  to go up one level in the directory structure

Adafruit also has a great tutorial about SSH and the Raspberry Pi.

 

STEP 4: INSTALL MODULES AND LIBRARIES

To run your bots, you’ll need to install any modules, packages, or libraries that they need.

First, make sure everything is up to date by running these two commands:

sudo apt-get update and sudo apt-get dist-upgrade

These will update your OS and installed packages – it may take a while, so now’s a good time to take a little break :)

All my bots run using Python, and if yours do too I suggest installing pip :

  1. Type sudo apt-get install python-setuptools
  2. Then install  pip  using sudo easy_install pip

Using  pip  and easy_install , you can install most packages. Other tools should be installed as needed. I particularly use python-twitter , tweepy , nltk , and pattern , all of which can be installed using pip .

 

STEP 5: MOVE YOUR BOTS

SSH is great, but it can’t be used to move files from one computer to another. You could drop your files onto a thumb drive, plug it into the Pi, and use some command-line magic to move the files, but that’s complicated! Instead, we can connect to the Pi via Secure File Transfer Protocol (SFTP), similar to how you upload files to a web server.

Screen Shot 2014-08-31 at 12.33.03 PM

  1. Open your FTP client of choice – above is a screenshot using Transmit, which is not free like Filezilla, but has a very good, easy to use interface. Filezilla and other FTP programs are very similar.
  2. Choose to connect via SFTP, then enter the following information:
    Server : <username>@raspberrypi , or the IP address of your Pi (same as SSH above)
    Username/password : the username and password we’ve been using above
  3. You’re connected! Make a new folder on the Desktop for your bots (or wherever you’d like) and drag-and-drop your files from your hard-drive.

 

STEP 6: SET UP AUTOMATIC POSTING

Last step! We now want to make our bot run automatically at a set interval. To do that, we have to edit the crontab , a system file for automating.

Screen Shot 2014-08-31 at 12.41.56 PM

  1. Using SSH, type  crontab -e  to edit the file in Nano (the same editor used above to enable auto-login)
  2. Scroll down to the bottom and type a cron configuration (more info below). For example:
    0 * * * * python ~/Desktop/Bots/MySuperCoolBot/MySuperCoolBot.py
  3. Hit  control-X  to exit, then  Y  followed by  Enter  to save the crontab

Cron commands can take a little getting used to. The above commands runs a python script called  MySuperCoolBot.py  located in the  Bots  folder on the  Desktop  once per hour on the hour. The five places (specified by numbers or an asterix) set minute (0–59), hour (0–23), day of month (1–31), month (1–12), and day of week (0/Sunday–6/Saturday).

A few more examples (from this great tutorial):

  • To run a bot every six hours on the hour:
    0 */6 * * * python ~/Desktop/Bots/MySuperCoolBot/MySuperCoolBot.py
  • To run a bot every day at 6:30pm:
    30 18 * * * python ~/Desktop/Bots/MySuperCoolBot/MySuperCoolBot.py
  • To run a bot at 8:00pm on weekdays only:
    0 20 * * 1-5 python ~/Desktop/Bots/MySuperCoolBot/MySuperCoolBot.py

 

STEP 7: SIT BACK AND WATCH YOUR BOTS!

That’s it – your bots are alive and posting. Ran into problems or got a bot running using these instructions? Post them in the comments below!

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11 Replies to “Setting Up Raspberry Pi To Run Bots”

  1. Since your ‘bots are running under the user python from Cron, you do not need to have your pi set to auto-login… My Pi computers never auto login, and all run headless and always work exactly as expected…

  2. I don’t know. I remember reading somewhere that it was required for either headless or SSH, but that might not be true? I wonder if there are any security reasons not to have it auto-login.

  3. Having auto-login means that anyone could use it when physically attached, when running headless and hidden away somewhere it doesn’t really matter but speaking with my security hat on, I prefer not to leave anything without a password as it is unnecessary.

    The other thing I noticed is that I often copy files to my pi from my file server (another Pi running Samba 3.6.6) without using ftp from an SSH remote terminal. Obviously I have the Samba server running anyway but if you have that then an FTP server is not required. I’m only mentioning this because you mention that SSH “can’t” be used to move files when, strictly speaking, it can…

    If you wanted to use a remote desktop then ‘apt-get install xrdp’ and you can log in using an xrdp client to our beloved Pi desktop from your other favourite desktop, although you’ll still need access to remote network shares to copy files between computers…

    I still cannot stop being surprised at how wonderfully effective a $40 credit card sized computer is…

  4. 28:00 isn’t eight o’clock. ;)

    But seriously, where are your Python scripts from? I knew most of everything else!

  5. Alas this section links to a dead page now…
    Can you turn on the video again via ssh if needed?

    Update: this post suggests that turning off video output (via RCA/HDMI) can save power consumption even more, especially for battery operation. Turn it off using the following command: /opt/vc/bin/tvservice -off, though it may not work on your device.

  6. Sorry my bad English,

    The thing is, to build a raspi-bot,
    which runs fast (a bit faster than human walk),
    entertains,
    knows his own position,
    talks
    understands spoken Commands(/ Conversation)
    and which is built modular,

    that means:
    the mechanical parts and the processing part
    should be exchangeable easily (chassis, botarms, RP, PowerPack, SwitchRelays …)

    I am sticking to the Problem of the weight, whenever i build a tiny bot. So i’m searching for a solution to switch the e-motors only by opto-coupler (without switch-relays).

    I (have to) struggle for easy and ‘lowbudget’ solutions.

    Till now, I could develop systems which can talk (voice), can check out there own position (without GPS), having interconnected communication, can drive, can recognize moving Persons, and act in some funny way.

    I try to get also the listening thing (speech2text),
    but therefore I need Google like smartphone(at the Moment).

    I do it all Linux-Shell and C-based, and I’m more passionated for autonom systems, not so good programmer,
    I have to learn a lot, and I can share some results.

    Thanks for this site

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