justintv

# If you work with git, you've probably had that nagging sensation of not knowing what branch you are on. Worry no longer!

export PS1="\\w:\$(git branch 2>/dev/null | grep '^*' | colrm 1 2)\$ "

# This will change your prompt to display not only your working directory but also your current git branch, if you have one. Pretty nifty!

# ~/code/web:beta_directory$ git checkout master
# Switched to branch "master"
# ~/code/web:master$ git checkout beta_directory
# Switched to branch "beta_directory"

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

gatlin

#!/bin/bash

# source: http://www.haskell.org/pipermail/haskell-cafe/2011-March/090170.html

sudo rm -rf /Library/Frameworks/GHC.framework
sudo rm -rf /Library/Frameworks/HaskellPlatform.framework
sudo rm -rf /Library/Haskell
rm -rf ~/.cabal
rm -rf ~/.ghc
rm -rf ~/Library/Haskell

gabrielfalcao

0 = Success
1 = Operation not permitted
2 = No such file or directory
3 = No such process
4 = Interrupted system call
5 = Input/output error
6 = No such device or address
7 = Argument list too long
8 = Exec format error

chaitanyagupta

Reader Macros in Common Lisp

This post also appears on lisper.in.

Reader macros are perhaps not as famous as ordinary macros. While macros are a great way to create your own DSL, reader macros provide even greater flexibility by allowing you to create entirely new syntax on top of Lisp.

Paul Graham explains them very well in [On Lisp][] (Chapter 17, Read-Macros):

The three big moments in a Lisp expression's life are read-time, compile-time, and runtime. Functions are in control at runtime. Macros give us a chance to perform transformations on programs at compile-time. ...read-macros... do their work at read-time.

lfender6445

Pry Cheat Sheet

• Youtube Tutorial 2013

Command Line

• pry -r ./config/app_init_file.rb - load your app into a pry session (look at the file loaded by config.ru)
• pry -r ./config/environment.rb - load your rails into a pry session

Debugger

rkaneko

Installing ag on CentOS

Prerequistes

• libpcre
• liblzma

Download, build and install

georgiana-gligor

Create PDF files from Markdown sources in OSX

When [Markdown][markdown] appeared more than 10 years ago, it aimed to make it easier to express ideas in an easy-to-write plain text format. It offers a simple syntax that takes the writer focus away from the formatting, thus giving her time to focus on the actual content.

The market abunds of editors to be used for help with markdown. After a few attempts, I settled to Sublime and its browser preview plugin, which work great for me and have a small memory footprint to accomplish that. To pass the results around to other people, less technical, a markdown file and a bunch of images is not the best approach, so converting it to a more robust format like PDF seems like a much better choice.

[Pandoc][pandoc] is the swiss-army knife of converting documents between various formats. While being able to deal with heavy-weight formats like docx and epub, we will need it for the more lightweight markdown. To be able to generate PDF files, we need LaTeX. On OSX, the s

rvl

Pushing to Multiple Git Repos

If a project has to have multiple git repos (e.g. Bitbucket and Github) then it's better that they remain in sync.

Usually this would involve pushing each branch to each repo in turn, but actually Git allows pushing to multiple repos in one go.

If in doubt about what git is doing when you run these commands, just

gunjanpatel

Revert the full commit

Sometimes you may want to undo a whole commit with all changes. Instead of going through all the changes manually, you can simply tell git to revert a commit, which does not even have to be the last one. Reverting a commit means to create a new commit that undoes all changes that were made in the bad commit. Just like above, the bad commit remains there, but it no longer affects the the current master and any future commits on top of it.

git revert {commit_id}

About History Rewriting

Delete the last commit

Deleting the last commit is the easiest case. Let's say we have a remote origin with branch master that currently points to commit dd61ab32. We want to remove the top commit. Translated to git terminology, we want to force the master branch of the origin remote repository to the parent of dd61ab32: