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%Q, %q, %W, %w, %x, %r, %s, %i

Perl-inspired notation to quote strings: by using % (percent character) and specifying a delimiting character.

Any single non-alpha-numeric character can be used as the delimiter, %[including these], %?or these?, %~or even these things~.

Strings

% or %Q

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Rails 7 new features. Before and After

• Add ComparisonValidator
• PostgreSQL generated columns
• PostgreSQL custom enum types
• Add tracking of belongs_to association
• association_previously_changed? method
• Add invert_where method
• Add associated method
• Add missing method
• Active Record Encryption

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# NOTE: This script assumes that you system is otherwise updated, ie no other update is pending.
# You can add this script into crontab to run every 5 mins: */5 * * * *

require 'open3'

Open3.popen3("softwareupdate -l --force") do |_stdin, _stdout, stderr, _thread|
  unless stderr.read.match? /No new software available./
    exec(%q{osascript -e "display notification \"You have an update available.\""})
  end
end

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#!/bin/bash
tmp=$(mktemp -d)
pushd "$tmp"

iso=/Users/lloeki/Downloads/archlinux-2015.08.01-dual.iso
echo "fixing disk"
dd if=/dev/zero bs=2k count=1 of=tmp.iso
dd if=$iso bs=2k skip=1 >> tmp.iso

echo "mounting disk"

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<!-- Generated by: TmTheme-Editor                 -->
<!-- ============================================ -->
<!-- app:  http://tmtheme-editor.herokuapp.com    -->
<!-- code: https://github.com/aziz/tmTheme-Editor -->
<plist version="1.0">
<dict>
	<key>name</key>
	<string>Duotone Dark</string>

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root@NanoPi-NEO-Air:~# git clone https://github.com/rm-hull/luma.core.git
Cloning into 'luma.core'...
remote: Counting objects: 1338, done.
remote: Compressing objects: 100% (29/29), done.
remote: Total 1338 (delta 12), reused 15 (delta 5), pack-reused 1304
Receiving objects: 100% (1338/1338), 376.52 KiB | 0 bytes/s, done.
Resolving deltas: 100% (791/791), done.
Checking connectivity... done.
root@NanoPi-NEO-Air:~# cd luma.core
root@NanoPi-NEO-Air:~/luma.core# pip install -e .

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For Windows:

• Download and install Putty

• Connect your USB to UART adapter from your computer to your Nano Pi Neo Air (or any COM device)

• Make sure you connect TX>RX and RX>TX (Sending/Receiving), otherwise both your devices are talking at the same time and neither one is being heard.

• On Windows OS, pull up the Device Manager

  • Run Windows (WinKey+R) and type in devmgmt.msc
    

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FROM alpine:3.7

RUN apk add --update-cache gcc libc-dev curl jemalloc-dev make linux-headers

RUN mkdir -p /usr/src/ruby
RUN cd /usr/src/ruby
RUN curl "https://cache.ruby-lang.org/pub/ruby/2.4/ruby-2.4.3.tar.gz" | tar -xz
RUN cd ruby-2.4.3 && ./configure --enable-shared --with-jemalloc --disable-install-doc && make

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Introduction

The MCP23017 is an I/O expander chip. It has 16 GPIO pins which you can control using an I2C interface using two pins from a Raspberry Pi, plus a power source and sink (which can also come from the Pi). It's not quite as simple as directly controlling the Pi's GPIO pins, but it's not complicated, either.

You need to install i2c-tools, which is probably in your distribution's package manager. You also need a kernel with I2C support; you might need to modprobe i2c-dev. It would presumably be possible to do without either of these things, and bitbang the I2C protocol over GPIO, but I don't understand the protocol well enough to try.

On pin numbering: if you like, you can refer to the datasheet for the MCP23017. There's a small dot in one corner of the chip, with a semi-circular cut-out at that end. The pin near

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ssh -C myproductionhost.com "sudo -u postgresuser PASSWORD="password" pg_dump production_database_name" | psql local_database_name