Using RegEx in an Editor's Search and Replace

\n is newline

\r is carriage return

^ is start of line

$ end of line or string (a \n comes after the end of the lin: $\n)



Example to find all blank lines:

^\s*$\n

Example replace , newline with , space

Search: ,\n
Replace: ,

When you search for metacharacters such as .[{()\^$|?*+, you need to escape them with backslash (\) so they can be recognized.

Use regex capturing groups and backreferences

In the search field, enter parentheses () that would indicate a capturing group, for example:

\stitle="(.*)?"\s*(/>*)

In the replace field, backreference such groups by numbers starting with 1, for example:

$2<title>$1</title>

Switch the character case in the replace statement

In the replace field, depending on what you want to achieve, for example /U$1.

Enter one of the following syntax:

• \l changes a character to lowercase until the next character in the string.
• For example, Bar becomes bar.
• \u changes a character to uppercase until the next character in the string.
• For example, bar becomes Bar.
• \L changes characters to lowercase until the end of the literal string (\E).
• For example, BAR becomes bar.
• \U changes characters to uppercase until the end of the literal string (\E).
• For example, bar becomes BAR.

Homebridge

Main guide to running Homebridge on a Raspberry Pi

https://github.com/nfarina/homebridge/wiki/Running-HomeBridge-on-a-Raspberry-Pi#basic-setup-preparations

Updated TP-Link HS-100 Smart Plug drivers

https://github.com/plasticrake/homebridge-tplink-smarthome

Python App running on AWS Beanstalk

Overview of Python virtual environments that is updated for Python 3.6
https://realpython.com/python-virtual-environments-a-primer/

Setting up Mac Terminal

Best summarised at:

https://medium.com/the-code-review/make-your-terminal-more-colourful-and-productive-with-iterm2-and-zsh-11b91607b98c

Make your terminal more colourful and productive with iTerm2 and Zsh!

Tired of a terminal with plain 12pt plain black text on plain white background? You can transform it from a monochrome experience to a more colourful one with added productivity features by installing:

• iTerm2
• Zsh
• Nerd fonts
• Powerlevel9k theme
• Color schemes
• Ruby gems

iTerm2

If you haven’t already, install the mac package manager homebrew.

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Install iTerm2 here or through homebrew with the below command. iTerm is is a customisable terminal for mac. This is the terminal that we will add loads of extra options to.

brew cask install iterm2

Zsh

Then install the zsh, an alternative to bash.

brew install zsh

The Z-shell resource file, ~/.zshrc, is a script that is run whenever you start Zsh. This tutorial will add things to this file to configure your terminal.

To change the default shell to Zsh rather than bash, run the change shell command in your terminal.

chsh -s /bin/zsh

Zsh-users have created some useful additions that integrate with it. One of the cool things you can add is syntax highlighting to colour command types. Another one is auto suggestions, which remember common commands that you can easily re-run.

Nerd fonts

To be able to have prompt with extra icons, such as for github, you need to install a special font set. This will show you how to install and configure nerd-fonts.

There are various options for installing nerd fonts. Here is the curl download option.

cd ~/Library/Fonts && curl -fLo "Droid Sans Mono for Powerline Nerd Font Complete.otf" https://github.com/ryanoasis/nerd-fonts/raw/master/patched-fonts/DroidSansMono/complete/Droid%20Sans%20Mono%20Nerd%20Font%20Complete.otf

Next setup iTerm2 to use the font by going to:

iTerm2 -> Preferences -> Profiles -> Text -> Font -> Change Font

Select the font Droid Sans Mono Nerd Font Complete and adjust the size if you want too. Also check the box for Use a different font for non-ASCII text and select the font again. It should be displaying the new font and icons in the prompt.

Powerlevel9k

There are many themes for for zsh, but my favourite is powerlevel9k.

You need to tell powerlevel9k to use the Nerd Font in your ~/.zshrc.

echo "POWERLEVEL9K_MODE='nerdfont-complete'" >> ~/.zshrc

Next install the powerleve9k theme from github and add the command to load it in your ~/.zshrc.

git clone https://github.com/bhilburn/powerlevel9k.git ~/powerlevel9k
echo 'source  ~/powerlevel9k/powerlevel9k.zsh-theme' >> ~/.zshrc

NOTE: The font needs to be set before Powerlevel9k is initialised in your ~/.zshrc.

POWERLEVEL9K_MODE='nerdfont-complete'
source ~/powerlevel9k/powerlevel9k.zsh-theme

Powerlevel9k is highly configurable. To change your setup, open your ~/.zshrc and add in the configuration your prefer. In the screenshots in this post I have used the following setup, which are listed in my ~/.zshrc.

POWERLEVEL9K_LEFT_PROMPT_ELEMENTS=(dir vcs newline status)
POWERLEVEL9K_RIGHT_PROMPT_ELEMENTS=()
POWERLEVEL9K_PROMPT_ADD_NEWLINE=true
DISABLE_UPDATE_PROMPT=true

If you are proud of you configuration, some people share theirs online, such as at Show-Off-Your-Config.

Colour schemes

There are many iTerm colour schemes out there. One source is iterm2colorschemes, which gives you about 175 choices. Once you have downloaded them, select iTerm -> Preferences -> Profiles -> Colors -> Color Presets -> Import then select the colour scheme you like. The one colour scheme I have used in this article’s pictures is Dracula.

You can make your ls command display coloured file names using your chosen colour scheme using the -G option. Add this as an alias to your ~/.zshrc file using:

echo "alias ls='ls -G'" >> ~/.zshrc

You can make your file lists match the colour scheme you have chosen if you set ‘ls -G’ as an alias for ‘ls’.

Ruby gems

If you code in Ruby — or want to start — there are some colourful Ruby gemsthat can take this further. The colorls gem is used in the image at the top of this post to colour the file types and add icons next to them.

• Install Ruby
• colorls: A Ruby gem that beautifies the terminal’s ls command, with color and font-awesome icons.
• lolcat: Rainbows and unicorns! Adds rainbow colours to your terminal output.

Read more about how to use colourful Ruby gems in my post Lolcat, Colorls, Catpix, and other Ruby Gems to add color to your terminal

Adding extra items

I would then add colorls, a Ruby gem

Install Ruby

brew install ruby

Install colorls

gem install colorls

More items... add the notes here

Apple Mac Set the location of screengrab files

Screengrabs on a Mac are automatically saved to the Desktop folder by default.

To change this folder, update the default settings in a terminal window using the following

$ defaults write com.apple.screencapture location /Volumes/MACUSB/downloads

Apple Mac Finder App Not Showing Folders in Siderbar - Favourites Missing in Sidebar

This Apple Mac problem is a regular enough occurrence that I'm making notes to remind what I need to fo to fix it to save me hunting around the web each time it happens.

It is particularly annoying to find all of your shortcuts, favourites and folder arrangements suddenly wiped out from your Apple Mac Finder Sidebar.

Some people find that turning it off and turning it back on again can reinstate the favourites, or, there is a plus/minus icon beside the favourites title that shows and hides the favourites. Sometimes, this can sort the problem out and sometimes it doesn't lose or forget all of the favourites you've setup.

How to fix missing sidebar in Apple Finer app

The fix, is simply to delete the com.apple.sidebarlists.plist file and then reboot your machine.

In my experience, this option forgets all of your favourites and you have to set them up from scratch, again.

Investigating linux server crashes - MySQL

MySQL Configuration

The MySQL configuration file can be found at

/etc/my.cnf

By default it does not create a separate log file for MySQL errors, but you can add a line to separate the error messages out.

log_error = /var/log/mysqld.log

MySQL Tuner

For suggestions on improving your MySQL configuration, install MySQL tuner. Run it after MySQL has been running for at least 24 hours. The more time the better the suggestions.

wget  http://mysqltuner.com/mysqltuner.pl
chmod +x  mysqltuner.pl

Then to run the program, you must be logged in as a user that has privileges to access MySQL. For me, it would not work as my usual user account and I solved the problem by logging in as root and changing to the directory that I wget'ed mysqltuner to.

./mysqltuner.pl

A sample output might be:

-------- Recommendations --------------------------------------------------------------------------- General recommendations: Control warning line(s) into /var/log/mysqld.log file Control error line(s) into /var/log/mysqld.log file Dedicate this server to your database for highest performance. Configure your accounts with ip or subnets only, then update your configuration with skip-name-resolve=1 When making adjustments, make tmp_table_size/max_heap_table_size equal Reduce your SELECT DISTINCT queries which have no LIMIT clause Set thread_cache_size to 4 as a starting value Performance shouldn't be activated for MySQL and MariaDB 5.5 and lower version Consider installing Sys schema from https://github.com/mysql/mysql-sys Variables to adjust: query_cache_size (=0) query_cache_type (=0) query_cache_limit (> 1M, or use smaller result sets) tmp_table_size (> 16M) max_heap_table_size (> 16M) thread_cache_size (start at 4) performance_schema = OFF disable PFS innodb_log_file_size * innodb_log_files_in_group should be equal to 1/4 of buffer pool size (=64M) if possible.

MySQL Log Files

The two main log files for MySQL will now both be in the following directory.

log-slow-queries=/var/lib/mysql/g9online-vps-slow.log
log_error = /var/log/mysqld.log

The Slow Query Log can be analysed using mysqldumpslow

mysqldumpslow /var/lib/mysql/g9online-vps-slow.log

It summarises the number of times the same query has been logged to the Slow Query log. By default, mysqldumpslow sorts by average query time but you can use the -s option to sort by t or at, query time, l or al, lock time, r or ar, rows sent or c, count.

Another useful options is -t N to display only the first N queries in the output.