Author: Malcolm Low

Dr. Malcolm Low is currently an Associate Professor with the Singapore Institute of Technology (SIT).

4×4 Rubik’s Cube Corner Parity

Here are the steps for fixing the 4×4 Rubik’s cube parity:

Steps: R2, T2, R2, TH2, R2, TH2

Here are the abbreviations:

R: Right

T: Top

TH: Top Half (for 4×4 this is the top two layers)

4×4 Rubik’s Cube Edge Parity

Here are the steps to fix the parity when solving a 4×4 rubik’s cube:

Edge Parity: RD1, T2, LD1, F2, LU1, F2, RD2, T2, RU1, T2, RD1, T2, F2, R2, F2

The abbreviations are as follows:

RD – Right Down

LD – Left Down

RU – Right Up

RD – Right Down

T – Top

F – Front

Hijacking huge chunks of the internet – a new How To • The Register

https://www.theregister.co.uk/2008/08/27/bgp_exploit_revealed

Quick Guide to nawk

Here is a quick guide to nawk. nawk as it has more functionalities over awk. Most systems now would have both programs installed. See also:

Quick Guide to Emacs

Here is a quick guide to emacs. These are a collection of commonly used keystrokes. See also:

Key Definitions

  • Ca-Cb : Press [Control][a] follow by [Control][b].
  • Ma-b : Press [Esc][a] follow by [b].
  • F1-t : Press function key [F1] follow by [t].

Tutorial

  • Please go through the Emacs tutorial If you haven’t done so: Ch-t or F1-t

Useful things to put in .emacs

  • Show line number : (line-number-mode 1)
  • Show column number : (column-number-mode 1)
  • Show time : (display-time)
  • Change color theme: (load-theme ‘deeper-blue t)

Navigations

  • Quit : Cx-Cc
  • Move between windows : Cx-o
  • Goto a line : Mg

Editing

  • Cut : Ck
  • Paste : Cy
  • Select/mark region : C[space]
  • Exchange mark and point : CxCx
  • Cut rectangle region : Cx-Rk
  • Paste rectangle region : Cx-Ry

Search

  • Quick search forward : Cs
  • Quick search backward : Cr

Keystroke Record/Playback

  • Record : Cx-(
  • Playback : Cx-)

Various Different useful modes

You can enhance XEmacs with various useful features. The following two packages can be installed with minimal effort. Email me if you require any help in installing them.

  • Flyspell : On-the-fly spelling checker.
  • X-Symbol : Enables the showing of superscript, subscript and greek characters in LaTex.

To check for grammar errors in Latex, the best way is to convert your Latex document to HTML and use one of the online Grammar checkers.

Quick Guide to CVS

Here is a quick guide to setting up and using CVS. The commands shown below were tested on Concurrent Versions System (CVS) 1.10 available from Cyclic Software.

See also:

Setup

  • Set CVSROOT to a directory (e.g. setenv CVSROOT ~/cvsroot )
  • Run “cvs init”

Put Project into CVS

  • To add version control for a project consist of multiple files in a directory, e.g. ~/project
  • cd to ~/project
  • Run “cvs import -m “Project” myproject sample start”
  • The respective arguments are :
  • cvs -m “Log message” repository vendor-tag release-tags
  • You can put anything you like for the tags and log message.
  • You will need to use “repository” to checkout your files later.

Checkout a Project

  • To checkout a project
  • Run “cvs checkout myproject”
  • You can subsitute “myproject” for any other repositories in the CVS.

Update a Project

  • To update a project after modifying several files
  • Run “cvs commit”
  • An editor will be shown to allow you to add comments on the changes
  • To use another editor eg: xemacs, do “setenv EDITOR xemacs”

Add/Remove File

  • To add a file, run “cvs add filename; cvs commit”
  • To remove a file, run “cvs remove filename; cvs commit”

Topics not covered here

  • Version branches
  • Multiple developers

See also this site for a more comprehensive tutorial.

Quick Guide to Mac Mini

Install Homebew

/bin/bash -c “$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)”

Add a directory to path

echo >> /Users/mlow/.zprofile
echo ‘eval “$(/opt/homebrew/bin/brew shellenv)”‘ >> /Users/mlow/.zprofile
eval “$(/opt/homebrew/bin/brew shellenv)”