Łukasz Herok

Torque

$$ {\boldsymbol {\tau }}=\mathbf {r} \times \mathbf {F} $$ $$ \tau =\|\mathbf {r} \|\,\|\mathbf {F} \|\sin \theta $$

#physics

Exploring table partitioning using the inheritance technique.

#postgresql

Moving data to another (archive) table with one query:

WITH moved_rows AS (
    DELETE FROM box_magldno.serialno
    WHERE tms::DATE <='2018-12-31'
    RETURNING *
)
INSERT INTO box_magldno.serialno_2018
SELECT * FROM moved_rows;

WITH Queries

#sql #postgresql

Read the temperature and pressure from the BMP280 sensor, using the bmp280 driver and Micropython plugin for Pycharm:

from machine import I2C
from bmp280 import BMP280

bus = I2C(scl=machine.Pin(5), sda=machine.Pin(4))
bmp = BMP280(bus)
bmp.pressure
>>> 97679.8
bmp.temperature
>>> 21.68

#arduino

Blinking the LED on the esp8266 with my son

import machine
pin = machine.Pin(2, machine.Pin.OUT)
pin.off()
pin.on()

#arduino

Regex for adjusting Jupyter notebook exported to markdown to the markdown rendered as HTML with MathJax

In-line math delimiters:

 \$\$(.*?)\$\$
 \\\\( $1 \\\\)

In-line numbers:

\$\$([\d\.]*?)\$\$
\\\\( $1 \\\\)

Matrices row separator:

\\begin\{bmatrix\}(.*?) \\\\ (.*?)\\end\{bmatrix\}
\\begin\{bmatrix\} $1 \\\\\\ $2 \\end\{bmatrix\}

Images:

!\[png]\((.*?)\)
<center>
    <figure class="figure text-center">
          <img width="80%" src="/static/art/002/$1" class="figure-img img-fluid rounded">
      <figcaption class="figure-caption text-center"></figcaption>
</figure>

Monitoring network traffic

netstat -tp
iftop
tcptrack -i eth0
ss -tn -o
watch -n 1 "ss -tn -o"

Commands to monitor network bandwidth on Linux

#linux

Adding the site to Google Index by requesting the indexing trough the Google Search Console.

#seo

Redirect www to the non-www domain for better google search.

How To Redirect www to Non-www with Nginx on CentOS 7

#linux #nginx

Journal of my recent activities