accessing array out from json_decode

to use associated arrays use below function
json_decode($string,true);

Installing Mongo for PHP on MacOS

Use below guide

https://stackoverflow.com/questions/36760759/mongoclient-not-found-in-php-on-mac-osx-using-brew

brew install php56-mongo

AWS auto snapshot and backup

refer:

https://github.com/CaseyLabs/aws-ec2-ebs-automatic-snapshot-bash

How to update nodejs

npm cache clean -f
sudo npm install -g n
sudo n stable

npm install npm@latest -g

how to download php composer

php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
php -r "if (hash_file('SHA384', 'composer-setup.php') === '544e09ee996cdf60ece3804abc52599c22b1f40f4323403c44d44fdfdd586475ca9813a858088ffbc1f233e9b180f061') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
php composer-setup.php
php -r "unlink('composer-setup.php');"

Install Tex2PNG on system

use below commands:

sudo apt-get install texlive-latex-base (for latex command)

install dvipng

use Tex2Png php library

https://github.com/Gregwar/Tex2png/blob/master/Tex2png.php

How to create detached byobu sessions

Below is process to create detached byobu sessions:

byobu-tmux new-session -d "sh ./api_build.sh"

php7 setup on ubuntu 16

https://www.howtoforge.com/tutorial/install-apache-with-php-and-mysql-on-ubuntu-16-04-lamp/

take direct screenshot from adb

adb shell screencap -p | perl -pe 's/\x0D\x0A/\x0A/g' > screen.png

ngrok.. expose localhost to internet

ngrok is great tool to expose internet to outside internet.

./ngrok http <port number>
http://localhost:4040/inspect/http

run it on byobu


Bhola Meena's ngrok end point is :  https://54f3ee7e.ngrok.io

How to reduce size of EC2 EBS volume

Latest link: https://medium.com/@rahulian/how-to-reduce-volume-of-an-aws-ec2-instance-d493ec891698

copy commands:

-aAxXSH

-aHAXxSP

attach two volume and issue below commands:

Block Device Name Big Volume = /dev/sda1

Block Device Name Big Volume Snapshot = /dev/sdg

Block Device Name Small Volume = /dev/sdf

Restart the Instance and SSH in

Login:

1	ssh -i <Private-key> ec2-user@ip-address

Create a file system for the 2 volumes you have created (Note: In Ubuntu I had to do a cat/proc/partitions to work out which device was which).

1 2	sudo mkfs -t ext4 /dev/xvdf sudo mkfs -t ext4 /dev/xvdg

Create two mount directories and mount the new volumes.

1 2 3 4

sudo mkdir /mnt/small sudo mount /dev/xvdf /mnt/small sudo mkdir /mnt/snap sudo mount /dev/xvdg1 /mnt/snap

Sync the files.

1	sudo rsync -aHAXxSP /mnt/snap/ /mnt/small

Unmount the smaller volume.

1	sudo umount /dev/xvdf

Stop the instance

link from:

http://cloudacademy.com/blog/amazon-ebs-shink-volume/

common bugs in PHP: Include same file name

If two files with same names available, then content of second include will not be read if include_once used.

include vs include_once : There is only one difference between include() and include_once(). If the code from a file has been already included then it will not be included again if we use include_once(). Means include_once() include the file only once at a time.

include vs require : if include() is not able to find a specified file on location at that time it will throw a warning however, it will not stop script execution. For the same scenario, require() will throw a fatal error and it will stop the script execution.

require vs require_once : There is only one difference between require() and require_once(). If the code from a file has been already included then it will not be included again if we use require_once(). Means require_once() include the file only once at a time.

Points with Online Education Seminar

1. Mindspark - leading adaptive learning co in india
2. only quality content will win in online education.
3. courses will replace the textbooks in future
4. online education like video game. need to tune for each students
5. swayam- india govt initiative

image optimization for websites

refer: https://jmperezperez.com/jpegoptim-optimize-jpg-page-speed/

jpegoptim
smushit for wordpress

In my opinion the best option out there that effectively handles most image formats in a go is trimage. It effectively utilizes optipng, pngcrush, advpng and jpegoptim based on the image format and delivers near perfect lossless compression.

The implementation is pretty easy if using a command line.

sudo apt-get install trimage    
trimage -d images/*

I use jpegoptim to optimize JPG files and optipng to optimize PNG files.

If you're on bash, the command to losslessly optimize all JPGs in a directory (recursively) is:
find /path/to/jpgs/ -type f -name "*.jpg" -exec jpegoptim --strip-all {} \;


You can add -m[%] to jpegoptim to lossy compress JPG images, for example:
 find /path/to/jpgs/ -type f -name "*.jpg" -exec jpegoptim -m70 --strip-all {} \;


To optimize all PNGs in a directory:
find /path/to/pngs/ -type f -name "*.png" -exec optipng -o2 {} \;


-o2 is the default optimization level, you can change this from o2 to o7. Notice that higher optimization level means longer processing time.

optimize() {

  jpegoptim *.jpg --strip-all

  optipng -o7 -preserve *.png

  for i in *

  do

    if test -d $i

    then

      cd $i

      echo $i

      optimize

      cd ..

    fi

  done

  echo

}

optimize