number of opened sockets

run ss -s util

kill all processes in single command

use
killall -KILL <proce name>

Detect hardcoded strings in android java files

1. click analyze menu in android studio

2. click inspect by name

3. enter "Hardcoded strings"

4. use filemask as "*.java"

5. fix issues one by one

run wordpress with ngnx

https://www.linode.com/docs/websites/nginx/how-to-install-nginx-and-php-via-fastcgi-on-ubuntu-12-04-lts-precise-pangolin

disable gedit auto saving

gsettings set org.gnome.gedit.preferences.editor create-backup-copy 'false'

how to mod_pagespeed cache

go to /var/cache/

how to take thread dump for java process

use jstack <pid>

conflict between node and nodejs

install below:

sudo apt-get install nodejs-legacy

setting up nginx on ubuntu

below url have good content:
https://www.digitalocean.com/community/tutorials/how-to-configure-nginx-as-a-reverse-proxy-for-apache

Aerospike - fast database system

try it
aerospike.com 

Allow remote access to mysql

bind mysql to 0.0.0.0

grant permission: GRANT ALL PRIVILEGES ON *.* TO 'myuser'@'%' WITH GRANT OPTION;
add user 'root'@'%' with password

FInd reject files recursively

use below command:

find $directory -type f -name "*.in"

scan opened port on a machine

use nmap utility.

Short bash prompt

use below in .bashrc

PROMPT_DIRTRIM=2

How to get complete android apk info

hint:
/home/bhola/android-sdk/sdk/build-tools/21.1.0/aapt dump badging app-x86-debug.apk 

Building apk for multiple architecture

productFlavors {
    defaultFlavor {
        proguardFile 'proguard-rules.txt'    }
    x86 {
        versionCode Integer.parseInt("6" + defaultConfig.versionCode)
        ndk {
            abiFilter "x86"        }
    }
    mips {
        versionCode Integer.parseInt("4" + defaultConfig.versionCode)
        ndk {
            abiFilter "mips"        }
    }
    armv7 {
        versionCode Integer.parseInt("2" + defaultConfig.versionCode)
        ndk {
            abiFilter "armeabi-v7a"        }
    }
    arm {
        versionCode Integer.parseInt("1" + defaultConfig.versionCode)
        ndk {
            abiFilter "armeabi"        }
    }
}

how to recover files in ubuntu

Boot into safe mode

run below command
mount -o remount,rw /

How to get original path of Java

use readlink -f /usr/bin/java

and set JAVA_HOME variable

How to build scalable PHP based webservices

1. Use facebook hhvm

https://github.com/facebook/hhvm/wiki


2. No sessions

Resources for learning GO language

Installing go:
1. mkdir ~/go
    mkdir ~/goprojects

Install go from golang.org site

Install goeclipse  ==> juno eclipse and install goeclipse plugin

Install gocode
go get -u github.com/nsf/gocode

setup environment variables in ~/.profile

export GOROOT=$HOME/go

export PATH=$PATH:$GOROOT/bin

export GOPATH=$HOME/goprojects

export PATH=$PATH:$GOPATH/bin

https://tour.golang.org/welcome/1

Golang book

http://www.golang-book.com/11/index.htm


Go Libraries:

https://github.com/Xelom/Go-Libraries


Debugging tips:

1. only variable with Capital letter are exported.

create snap of first page of book

 pdftoppm -f 1 -singlefile -scale-to 400 casample.pdf -png page

allow cross origin headers

Header set Access-Control-Allow-Origin "*" 

How to extract pages from a pdf file

use below command:

pdftk in.pdf cat 1 2 5-8 output out.pdf

installing mcrypt

sudo apt-get install mcrypt

sudo php5enmod mcrypt

apache restart

git how to discard last commit

git push origin HEAD --force

git untrack file without deleting

git update-index --assume-unchanged

nodejs using variable in function scope

use function scope

(function(v){
})
(v2);

uploading file through ajax

use jquery.form plugin

ajaxform........

debugging ajax error in jquery

error: function(err) {
  alert(err.responseText);
   },

How to apply patch in git

check logs
git log --pretty=oneline -3

git format-patch <patch number > master

git format-patch commitStart^..commitLatest --stdout > test.patch

git format-patch HEAD~

git apply --check <patch name>

git apply --reject --ignore-whitespace <patch name>

enabling moto g for ubuntu debugging

1. tap 7 time on build number

2. use sudo to start adb sever

use android rules

1. Log in as root and create this file: /etc/udev/rules.d/51-android.rules.
   Use this format to add each vendor to the file:
   SUBSYSTEM=="usb", ATTR{idVendor}=="0bb4", MODE="0666", GROUP="plugdev"
   
   In this example, the vendor ID is for HTC. The MODE assignment specifies read/write permissions, and GROUPdefines which Unix group owns the device node.
   Note: The rule syntax may vary slightly depending on your environment. Consult the udev documentation for your system as needed. For an overview of rule syntax, see this guide to writing udev rules.
2. Now execute:
   chmod a+r /etc/udev/rules.d/51-android.rules

handling back on notification activities

below is right thing to do:

You need to add the parent stack for the activity you're launching, not the parent of it.

Replace:

stackBuilder.addParentStack(MainActivity.class);

with:

stackBuilder.addParentStack( MatchActivity.class );

This assumes that you've defined the parent in your Manifest (API 16+):

<activity android:name=".MatchActivity"
    android:parentActivityName=".MainActivity"
    ... />

how to empty a file without deleting it

truncate logfile --size 0

How to change env variable for all users

edit
/etc/environment

Nodejs and async handling

below is great blog about it:

http://www.sebastianseilund.com/nodejs-async-in-practice

gearman and node.js

install

npm install node-gearman

https://www.npmjs.com/package/gearmanode

worker code example:


var nodejspath='/var/www/node_js/node_modules';
var gearmanode = require(nodejspath+'/gearmanode');
var worker = gearmanode.worker();

worker.addFunction('gcm_ca_nodejs', function (job) {
    console.log("got input as "+job.payload.toString());
    job.workComplete("done");
});

learn node.js

http://nodeschool.io/#workshoppers

install globally:

npm -g install <>


export NODE_PATH='/usr/loca/lib/node_modules'


including other javascript files

module.exports = {
  foo: function () {
    // whatever
  },
  bar: function () {
    // whatever
  }
};

using sqlite as gearman persistent queue

create sqlite db
sqlite3 gear-queue.db

CREATE TABLE gearman_queue(unique_key TEXT PRIMARY KEY,function_name TEXT,when_to_run INTEGER,priority INTEGER,data BLOB);

vi /etc/default/gearman-job-server

params="gearmand -q libsqlite3 --libsqlite3-db=/tmp/xx.sqlite"

setup gearman monitor

install https://github.com/yugene/Gearman-Monitor

2. install pear package

sudo pear install Net_Gearman-0.2.3

ssl security test

it can be done using ssllabs.com

Tips for s3sf performance improvements

1. use max_stat_cache_size="100000" 

2. use use_cache=/tmp/cache

Getting started with Windows Azure tools on Ubuntu

1. install npm

sudo apt-get install nodejs-legacy

2, install azure cli tools through

sudo npm install azure-cli -g

enable ssl on apache2

sudo a2ensite default-ssl
sudo a2enmod ssl

create below dir:
/etc/apach2/ssl.crt
/etc/apache2/ssl.key
/etc/apache2/ca-bundle

ssl.key should be from CSR


remove pass phrase

/path/to/openssl rsa -in /path/to/originalkeywithpass.key -out /path/to/newkeywithnopass.key

write way to handle non-www to www migration in apache

add below lines in vhost conf:

  RewriteEngine on
        RewriteCond %{HTTP_HOST} !^www\.
        RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

running amazon cli cron jobs

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

AWS_CONFIG_FILE="/home/ubuntu/.aws/config"
36 7 * * * sh /var/www//scripts/amz-stop.sh >/home/ubuntu/logs/amz-stop.log 2>&1
5 7 * * * sh /var/www//scripts/amz-launch.sh >/home/ubuntu/logs/amz-start.log
2>&1

Hosting s3 files

use CNAME to host s3.

Name of bucket should be same as CNAME

http://download.onlinetyari.com ==> http://download.onlinetyari.com.s3.amazonaws.com 

S3FS and git together

use below to forcefully write in git

git fetch 
git reset --hard origin/master

Useful mysql debugging commands

Total tables:

SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE='BASE TABLE';

show global status  like 'open%';

SHOW VARIABLES LIKE '%max%'

how to mount s3 for website write

find uid and gid
id -i www-data
id -g www-data

chmod -R 1777 /file_name

sudo s3fs ot-cdn /var/www/ot/cdn -o uid=1000,gid=33,use_rrs=1,allow_other,default_acl=public-read,umask=002,use_cache=/home/ubuntu/cdn

how to unmount s3fs mount point

sudo fusermount -u /var/

setup s3fs fuse on amazon ec2 machine

apt-get install build-essential git libfuse-dev libcurl4-openssl-dev libxml2-dev mime-support automake libtool
apt-get install pkg-config libssl-dev # See (*3)
apt-get lib-xml2 lib-xmlv2

git clone https://github.com/s3fs-fuse/s3fs-fuse
cd s3fs-fuse/
./autogen.sh
./configure --prefix=/usr --with-openssl # See (*1)
make
sudo make install

create ~/.passwd_s3fs

chmod 600 ~/.passwd_s3fs

keys in <k1>:</k2> format

s3fs <b> /mnt

how to sync local file content to s3 bucket

use below command:

aws s3 sync . s3://********/ --acl=public-read

display last 5 modified files

ls -lt | head -n 5

how to install amazon CLI

sudo apt-add-repository ppa:awstools-dev/awstools
sudo apt-get update
sudo apt-get install ec2-api-tools

$ curl "https://s3.amazonaws.com/aws-cli/awscli-bundle.zip" -o "awscli-bundle.zip"
$ unzip awscli-bundle.zip
$ sudo ./awscli-bundle/install -i /usr/local/aws -b /usr/local/bin/aws
$aws configure

How to use PhpMyadmin for RDS management

use below code in /etc/phpmyadmin/config.inc.php

$cfg['Servers'][$i]['host'] = 'path';
$cfg['Servers'][$i]['port'] = '3306';
$cfg['Servers'][$i]['socket'] = '';
$cfg['Servers'][$i]['connect_type'] = 'tcp';
$cfg['Servers'][$i]['extension'] = 'mysql';
$cfg['Servers'][$i]['compress'] = TRUE;
$cfg['Servers'][$i]['auth_type'] = 'cookie';
$cfg['Servers'][$i]['user'] = 'root';
$cfg['Servers'][$i]['password'] = '';

creating database on AWS RDS platform

Below is how to create database directly using mysql command line......

1. CREATE DATABASE testdb2 DEFAULT CHARACTER SET utf8 DEFAULT COLLATE utf8_general_ci