Linux

pi

back to pi and pine

keep shit in c://iot/pi user ubuntu paswd Pinj

in winscp new sessions window edit advanced advanced shell shell sudo-s from dropdown

http://yannickloriot.com/2016/04/install-mongodb-and-node-js-on-a-raspberry-pi/

installed node with the 16.04 instructions using nvm

• http://raspberrypi.stackexchange.com/questions/45319/install-newer-node-version-on-pi-3

http://raspberrypi.stackexchange.com/questions/48056/login-as-root-not-possible

systemctl start mongodb
systemctl enable mongodb

getting started

• get sd formatter https://www.sdcard.org/downloads/formatter_4/eula_windows/index.html
• get noobs https://www.raspberrypi.org/downloads/noobs/
• run sdformatter
• unzip noobs and load files on sdcard
• connect keyboard and monitor and internet and power up the pi and install raspbian

setting up python

sudo apt-get update
sudo apt-get python-pip
sudo apt-get install python-dev
sudo pip install virtualenv

create a project directory

cd projdir
virtualenv venv

running in a virtualenv doesn't work because pi doesn't have access to /dev/mem which is used by GPIO

so all the following commmands need sudo

install flask

pip install Flask

install gevent

pip install gevent 
pip install RPi.GPIO
pip install -U flask-cors

sudo python cascada2.py

default

user pi passwd raspberry

current

pi@10.0.1.155 ranj..

login loop

-bash: error while loading shared libraries: libtinfo.so.5: cannot open shared object file or directory

http://raspberrypi.stackexchange.com/questions/36467/how-to-repair-login-loop-bash-error

https://www.raspberrypi.org/forums/viewtopic.php?uid=159601&f=28&t=120846&start=0

https://www.raspberrypi.org/forums/ucp.php

bluetooth 4.0 LE

http://www.ioncannon.net/linux/1570/bluetooth-4-0-le-on-raspberry-pi-with-bluez-5-x/

http://www.elinux.org/RPi_Bluetooth_LE

python

jupyter on python3

https://www.digitalocean.com/community/tutorials/how-to-set-up-a-jupyter-notebook-to-run-ipython-on-ubuntu-16-04

is installed in omen www/environments/jup

tim@omen:/d/fs/www/environments$ pyvenv jup
tim@omen:/d/fs/www$ cd environments/
tim@omen:/d/fs/www/environments$ . jup/bin/activate
(jup) tim@omen:/d/fs/www/environments$ jupyter notebook

(jup) tim@omen:/d/fs/www/environments/jup/bin$ deactivate

accessing object properties

status ={}
status['pond'] = {'spot': 'center', 'state': 'off', 'tleft': 0, 'nexton': 9}

status['pond']['tleft']= 16

basic tutorial

https://thenewcircle.com/static/bookshelf/python_fundamentals_tutorial/advanced_types_containers.html

running app forever - supervisorctl

cascada

port = 8087

/home/pi/mypi/cascada/server/cascada.py

cascada2

port = 8088

/home/pi/mypi/cascada/server/cascada2.py

<markdown>

sudo`supervisorctl` reads configuration from `/etc/supervisor/conf.d` and runs whatever files if finds there.

a typical `conf` ile looks like:

   [program:cascada2]
   command=/usr/bin/python /home/pi/mypi/cascada/server/cascada2.py
   directory=/home/pi/mypi/cascada/server
   autostart=true
   autorestart=true
   startretries=3
   stderr_logfile=/var/log/cascada/cascada2.err.log
   stdout_logfile=/var/log/cascada/cascada2.out.log
   user=root
   environment=SECRET_PASSPHRASE='this is secret',SECRET_TWO='another secret'

you may have to `>supervisor reload` then `ctrl c` the `sudo supervisorctl` to get a new program running forever

</markdown>

pi@raspberrypi ~ $ sudo supervisorctl
cascada                          RUNNING    pid 2273, uptime 7 days, 3:17:36

tail -f /var/log/cascada/cascada.out.log
tail -f /var/log/cascada/cascada.err.log

after changing cascada.py

pi@raspberrypi ~ $ sudo supervisorctl
cascada                          RUNNING    pid 2273, uptime 7 days, 3:17:36
supervisor> stop cascada

exit w ctrl C

sudo lsof -i :8087
sudo kill -9 21118 (kill whatever port lsof returns)

pi@raspberrypi ~ $ sudo supervisorctl
cascada                          STOPPED    Jul 16 04:34 PM
supervisor> start cascada
cascada: started
supervisor>

exit w ctrl C ??

• nohup python app.py &
• use screen
• run supervisord(link) on system startup and control all through it (pythonic way :))

nohup means: do not terminate this process even when the stty is cut off.

& at the end means: run this command as a background task.

forever with supervisord

SSE - Server Side Events

http://flask.pocoo.org/snippets/116/

https://github.com/stevenewey/ssedemo

for node

https://www.npmjs.com/package/simple-sse (has room,haven't tried)

https://tomkersten.com/articles/server-sent-events-with-node/

http://www.futureinsights.com/home/real-time-the-easy-way-with-eventsource-angularjs-and-nodejs.html

SocketIO

http://stackoverflow.com/questions/17641602/how-to-emit-to-room-in-socket-io

flask socketio

https://flask-socketio.readthedocs.org/en/latest/

ibeacon

http://www.jaredwolff.com/blog/get-started-with-bluetooth-low-energy/ decribes gattr tool as well

xyfindit

00:eb:19:00:b7:b9,07775dd0111b11e491910800200c9a66,6400,47033,-59,-68

android

https://github.com/alt236/Bluetooth-LE-Library---Android

distance

http://stackoverflow.com/questions/20416218/understanding-ibeacon-distancing

http://en.wikipedia.org/wiki/DBm

The iBeacon output power is measured (calibrated) at a distance of 1 meter. Let's suppose that this is -59 dBm (just an example). The iBeacon will include this number as part of its LE advertisment.

The listening device (iPhone, etc), will measure the RSSI of the device. Let's suppose, for example, that this is, say, -72 dBm.

Since these numbers are in dBm, the ratio of the power is actually the difference in dB. So:

ratio_dB = txCalibratedPower - RSSI To convert that into a linear ratio, we use the standard formula for dB:

ratio_linear = 10 ^ (ratio_dB / 10) If we assume conservation of energy, then the signal strength must fall off as 1/r^2. So:

power = power_at_1_meter / r^2. Solving for r, we get:

r = sqrt(ratio_linear) In Javascript, the code would look like this:

function getRange(txCalibratedPower, rssi) {

   var ratio_db = txCalibratedPower - rssi;
   var ratio_linear = Math.pow(10, ratio_db / 10);

   var r = Math.sqrt(ratio_linear);
   return r;

} Note, that, if you're inside a steel building, then perhaps there will be internal reflections that make the signal decay slower than 1/r^2. If the signal passes through a human body (water) then the signal will be attenuated. It's very likely that the antenna doesn't have equal gain in all directions. Metal objects in the room may create strange interference patterns. Etc, etc... YMMV.

shareeditflag edited Feb 7 '14 at 2:19

answered Feb 7 '14 at 1:24

Mark Fassler 43135

http://stackoverflow.com/questions/15687332/bluetooth-le-rssi-for-proximity-detection-ios

estimote

Hi Wojtek,

Yep I got them and they are an exciting technology. But I must live in a 2.4 ghz jungle. That and the interesting variability you get between dog lying down, standing up and walking around can alter their signal markedly. Add to that the changes to the signal as I move about the house with my phone and you have a real puzzle.

I have better luck fixing by fixing my bluetooth receiver(s) and not detecting the beacons from mobile devices.

So I have set up raspberry pi's at key points in the yard to track the beacons. Using the libraries Bluez and Bluepy. I am able to estimate distance using the dB difference between the RSSI and the dB at 1 meter to get a power ratio that varies with the square of the distance. It is still cranky but once I put a few pi's in the yard I'll have boatloads of data to play around with.

It will be interesting to try out some filters, maybe put the data through a Hidden Markov Model or train up a neural network.

I have got some other beacons from other manufacturers and they all have similar variability. What would keep my concentration on Estimotes would be a bit of information on the Unknown Services that show up on scans. In particular, you advertise your beacons as standing out with capabilities like the accelerometer on board. How do I read that?

Meanwhile, the pi's are running a little restful API and some socket.io to communicate with my mobile devices and laptops. I'll have a mobile friendly responsive design HTML5/javascript app running soon. If I was doing dedicated I'd start on Android before IOS.

Thanks for your offer of help. Good luck with your product. The potential is enormous.

unix

http://www.namhuy.net/3116/how-to-fix-gpg-error-no_pubkey-in-ubuntu.html

commands

chmod -R 777 /var/backups/dog
sudo chown -R tim www
du -ah /var/www //gives size of directory and everything in it
vim . //opens vim with directory tree
rename_a_file mv oldname newname
landscape-sysinfo
grep -r "siteUrlis dog" /var/www/fworks/meteor/epool //search for text recursively
sudo ps -x | grep meteor
sudo kill -s KILL 29484
df list filesystem
sudo halt -p shuts down power
sudo ifconfig find ip adress etho innet addr is lan ip (ipconfig on windoows)

locate

sudo apt-get updat sudo apt-get install mlocate sudo updatedb locate libtinfo.so.5

e2fsck

finding port of address already in use

  $ sudo netstat -nlp | grep 80
  tcp  0  0  0.0.0.0:80  0.0.0.0:*  LISTEN  125004/nginx

or

 # sudo lsof -i :25
 COMMAND  PID        USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
 exim4   2799 Debian-exim    3u  IPv4   6645      0t0  TCP localhost:smtp (LISTEN)
 exim4   2799 Debian-exim    4u  IPv6   6646      0t0  TCP localhost:smtp (LISTEN)

home ubuntu

Ubuntu 12.04LTS

sudo halt -p

/etc/network/interfaces to make 10.0.1.101 static

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet static
address 10.0.1.101
netmask 255.255.255.0
gateway 10.0.1.1
dns-nameservers 8.8.8.8 10.0.1.1

lamp

https://www.digitalocean.com/community/articles/how-to-install-linux-apache-mysql-php-lamp-stack-on-ubuntu

http://10.0.1.101/info.php

ruby1.9.3 rails4.0.0

https://www.digitalocean.com/community/articles/how-to-install-ruby-on-rails-on-ubuntu-12-04-lts-precise-pangolin-with-rvm

tools

perl

• one liners
• http://www.somacon.com/p127.php

handy code

remove blank lines from file

perl -wnl -e 'print $_ unless /^$/' infile.txt >outfile.txt

sed awk

• SED tutorial
• http://tech.bluesmoon.info/2008/09/programming-patterns-in-sed.html
• http://www.vectorsite.net/tsawk_2.html

lib/images/toolbar/list_ul.png

lib/images/toolbar/rule.png

lib/tpl/default/images/interwiki.png

People with shell access to their server can copy the text above and paste it into a file on the system, then run the following commands to check for and remove all those files. Only those that exist are removed.

grep -Ev "^($|#)" /tmp/removeold.txt | xargs -n 1 rm -f

If you are paranoid, replace the "rm -f" with "ls -la" to see what files will be deleted.

To remove directories as well as files you have to use: grep -Ev "^($|#)" /tmp/removeold.txt | xargs -n 1 rm -fd

However, some systems may not support the "rm -d" option for directory removal. In that case, you have to use recursive removal (just be sure to double-check that the file list does not include any paths that will delete too much): grep -Ev "^($|#)" /tmp/removeold.txt | xargs -n 1 rm -fr

regex

https://alligator.io/js/regular-expressions-for-regular-people/

http://exploringjs.com/impatient-js/ch_regular-expressions.html

https://www.smashingmagazine.com/2019/02/regexp-features-regular-expressions/

https://regex101.com/

php example

 $search = array(
   '@<script[^>]*?>.*?</script>@si',   // Strip out javascript
   '@<[\/\!]*?[^<>]*?>@si',            // Strip out HTML tags
   '@<style[^>]*?>.*?</style>@siU',    // Strip style tags properly
   '@<![\s\S]*?--[ \t\n\r]*>@'         // Strip multi-line comments
 );

   $output = preg_replace($search, , $input);
   return $output;
 }

?> <?php function sanitize($input) {

   if (is_array($input)) {
       foreach($input as $var=>$val) {
           $output[$var] = sanitize($val);
       }
   }
   else {
       if (get_magic_quotes_gpc()) {
           $input = stripslashes($input);
       }
       $input  = cleanInput($input);
       $output = mysql_real_escape_string($input);
   }
   return $output;

}

typical

A username fro 3- 16 characters w -or_ /^[a-z0-9_-]{3,16}$/

a password 6-18 long /^[a-z0-9_-]{6,18}$/

a hex number /^#?([a-f0-9]{6}|[a-f0-9]{3})$/

a number sign is optional because it is followed a question mark but if there takes it(greedy)

6 characters or 3 character

a slug /^[a-z0-9-]+$/

beginning of the string (^), followed by one or more (the plus sign) letters, numbers, or hyphens. and the end of the string ($).

an email /^([a-z0-9_\.-]+)@([\da-z\.-]+)\.([a-z\.]{2,6})$/

. get delimited \.

each section in parens

only lower case, nubers or dots'/[^a-z0-9.]/'

url /^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$/

s? s if you got em

delimit / and . with \

you don't need http at all (https?:\/\/)? but be greedy

\d is any number

([\da-z\.-]+) numbers letters dotts or hyphens

\.([a-z\.]{2,6})~ .com .co .commie

([\/\w \.-]*)*\/?$/ files and directories

([\/\w \.-]*) * is zero or more, \w is words

html tag /^<([a-z]+)([^<]+)*(?:>(.*)<\/\1>|\s+\/>)$/

.* any characters

([^<]+) any characters but a <

(?:>(.*)<\/\1>|\s+\/>) non-capture group.it will contain either a greater than sign, some content, and a closing tag; or some spaces, a forward slash, and a greater than sign \1 represents the content that was captured in the first capturing group

no dots: ^[^\.]*$

^ - beginning of string
[^\.]* - any character except ., any number of repetitions
$ - end of string

replace spaces and punctuation with nothing str.replace(/\W/g, )

\W not letters digits or underscores

to take out all non alpha characters (Ruby)

 test_str = "Madam, I'm Adam"
 str = test_str.gsub(/[^a-zA-Z]/,'')
 puts str
returns MadamImAdam

• ^[ \t]+ //finds all the space and tabs
• [1-9]\. //finds all the line numbers. (replace with #)
• [A-E]\. //find A. etc (replace with ##)

to clean special characters from a string

$clean = preg_replace("/^[^a-z0-9]?(.*?)[^a-z0-9]?$/i", "$1", $text);

sites

• http://rubular.com
• http://e-texteditor.com/blog/2010/beyond-vi
• http://www.grymoire.com/Unix/Regular.html#uh-2
• http://www.regular-expressions.info/php.html
• http://www.bluebox.net/about/blog/2013/02/using-regular-expressions-in-ruby-part-1-of-3/

expressions

If you want to get'Aloha World'out

Input:

Hello World

Aloha World

Hey There

RegEx:

  \<div\sclass\=\"somename\"\>(?<Text>.*?)\<\/div\>

Yields:

Aloha World (note: In a single group named Text)