techgaun

So you want to modify the text of a PDF by hand...

If you, like me, resent every dollar spent on commercial PDF tools, you might want to know how to change the text content of a PDF without having to pay for Adobe Acrobat or another PDF tool. I didn't see an obvious open-source tool that lets you dig into PDF internals, but I did discover a few useful facts about how PDFs are structured that I think may prove useful to others (or myself) in the future. They are recorded here. They are surely not universally applicable --
the PDF standard is truly Byzantine -- but they worked for my case.

techgaun

## IPv6 Tests
http://[::ffff:169.254.169.254]
http://[0:0:0:0:0:ffff:169.254.169.254]

## AWS 
# Amazon Web Services (No Header Required)
# from http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html#instancedata-data-categories
http://169.254.169.254/latest/meta-data/iam/security-credentials/dummy
http://169.254.169.254/latest/user-data
http://169.254.169.254/latest/user-data/iam/security-credentials/[ROLE NAME]

techgaun

-- show running queries (pre 9.2)
SELECT procpid, age(query_start, clock_timestamp()), usename, current_query 
FROM pg_stat_activity 
WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%' 
ORDER BY query_start desc;

-- show running queries (9.2)
SELECT pid, age(query_start, clock_timestamp()), usename, query 
FROM pg_stat_activity 
WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%' 

techgaun

• http://the-paper-trail.org/blog/distributed-systems-theory-for-the-distributed-systems-engineer/
• https://github.com/palvaro/CMPS290S-Winter16/blob/master/readings.md
• http://muratbuffalo.blogspot.com/2015/12/my-distributed-systems-seminars-reading.html
• http://christophermeiklejohn.com/distributed/systems/2013/07/12/readings-in-distributed-systems.html
• http://michaelrbernste.in/2013/11/06/distributed-systems-archaeology-works-cited.html
• http://rxin.github.io/db-readings/
• http://research.microsoft.com/en-us/um/people/lamport/pubs/pubs.html
• http://pdos.csail.mit.edu/dsrg/papers/
• http://scalingsystems.com/2011/09/07/reading-list-for-distributed-systems/
• http://courses.engr.illinois.edu/cs525/sp2011/sched.htm

techgaun

Studying for a Tech Interview Sucks, so Here's a Cheat Sheet to Help

This list is meant to be a both a quick guide and reference for further research into these topics. It's basically a summary of that comp sci course you never took or forgot about, so there's no way it can cover everything in depth. It also will be available as a gist on Github for everyone to edit and add to.

Data Structure Basics

###Array ####Definition:

• Stores data elements based on an sequential, most commonly 0 based, index.
• Based on tuples from set theory.

techgaun

Installing OpenSSH 7.4 on Ubuntu 16.04

sudo apt install -y build-essential libssl-dev zlib1g-dev
wget "http://mirrors.evowise.com/pub/OpenBSD/OpenSSH/portable/openssh-7.4p1.tar.gz"
tar xfz openssh-7.4p1.tar.gz
cd openssh-7.4p1
./configure
make
sudo make install

techgaun

This has been tested on Raspbian

Install Erlang 19.2

apt-get install -y libssl-dev ncurses-dev
wget http://www.erlang.org/download/otp_src_19.2.tar.gz
wget -q -O - https://raw.githubusercontent.com/techgaun/extract/master/extract >> ~/.bashrc # I already had [this](https://github.com/techgaun/extract)
extract otp_src_19.2.tar.gz
cd otp_src_19.2

techgaun

Last updated: 2017-03-22 : Update to 1.2.2

The following assumes you're executing as a root user

Pre-install

yum update
yum install -y git
mkdir -p /opt/influx/{wal,data,ssl}

techgaun

Script

#!/bin/bash

yum install ncurses-devel openssl-devel -y
yum groupinstall "Development Tools" -y

cd /tmp
wget "http://erlang.org/download/otp_src_21.3.tar.gz" -O otp21.tar.gz

techgaun

Get all the keys in jsonb fields

select distinct jsonb_object_keys(sfdata) from accounts;

Get values of given key that's more than 0 in jsonb field

select (sfdata->>'BUILDING_SIZE__C')::float from accounts where (sfdata->>'BUILDING_SIZE__C' = '') is false and cast(sfdata->>'BUILDING_SIZE__C' as float) > 0 limit 5;