itsprdp

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

• -E: will describe the underlaying queries of the \ commands (cool for learning!)
• -l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

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Note

This tutorial is for Ubuntu & Squid3. Use AWS, Google cloud, Digital Ocean or any services with Ubuntu to follow this tutorial.

Install squid & update

sudo apt-get update
sudo apt-get install squid3
sudo apt-get install apache2-utils

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Find the original here article here: Devops Best Practices

DevOps started out as "Agile Systems Administration". In 2008, Andrew Shafer did a talk called "Agile Infrastucture" addressing issues around involving more of the company in the same disciplines as programmers.

In 2009, Patrick Debois created "DevOpsDays" conference to help to bring it to light. However, it wouldn't begin to trend until about 2010, when people would begin to describe it as a standalone discipline.

Today, DevOps goes beyond just developers, systems administration and infrastructure, its about [dev, ops, agile, cloud

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ffmpeg

Converting Audio into Different Formats / Sample Rates

Minimal example: transcode from MP3 to WMA:
ffmpeg -i input.mp3 output.wma

You can get the list of supported formats with:
ffmpeg -formats

Convert WAV to MP3, mix down to mono (use 1 audio channel), set bit rate to 64 kbps and sample rate to 22050 Hz:

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#!/bin/sh
# based on https://gist.github.com/ipedrazas/9c622404fb41f2343a0db85b3821275d

# delete all evicted pods from all namespaces
kubectl get pods --all-namespaces | grep Evicted | awk '{print $2 " --namespace=" $1}' | xargs kubectl delete pod

# delete all containers in ImagePullBackOff state from all namespaces
kubectl get pods --all-namespaces | grep 'ImagePullBackOff' | awk '{print $2 " --namespace=" $1}' | xargs kubectl delete pod

# delete all containers in ImagePullBackOff or ErrImagePull or Evicted state from all namespaces

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package main

import (
	"log"
	"time"

	"golang.org/x/net/context"
	"google.golang.org/grpc"

	pb "github.com/jzelinskie/grpc/simple"

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Apps

• Postico client for mac
• pgcli - Postgres CLI with autocompletion and syntax highlighting
• pghero - Server and query performance dashboard

Tools

• PostgreSQL's explain analyze made readable

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Warden::Manager.serialize_into_session{|user| user.id }
Warden::Manager.serialize_from_session{|id| User.get(id) }
 
Warden::Manager.before_failure do |env,opts|
  # Sinatra is very sensitive to the request method
  # since authentication could fail on any type of method, we need
  # to set it for the failure app so it is routed to the correct block
  env['REQUEST_METHOD'] = "POST"
end
 

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# NullStorage provider for CarrierWave for use in tests.  Doesn't actually
# upload or store files but allows test to pass as if files were stored and
# the use of fixtures.
class NullStorage
  attr_reader :uploader

  def initialize(uploader)
    @uploader = uploader
  end

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Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs