Tag Archives: Code

Calculate Your GPA Using this Bash Script

This Bash script is used to calculate your Grade Point Average (GPA) on the command line. Usage might not be intuitive. Please see the usage function or just run the script without passing it any arguments.

The gval function should be edited to reflect your own region or university. It has been written and tested on Bash 3.2.48.

# Bash GPA calculator
# Isam | r0cketjump@yahoo.com | biodegradablegeek.com
# 05/21/2009 - Just another 4 AM project

function usage {
  echo -e "\nBASH GPA Calculator"
  echo -e "\tAccepts an even # of arguments in the form of C G C G C G ..."
  echo -e "\t (C = number of credits, G = grade for the course)"
  echo -e "\tExample: You got a B+ in a 4 credit course, "
  echo -e "\t         an A in a 3 credit course, etc.."
  echo -e "\tUSAGE: $0 4 B+ 3 A 3 F 3 B-"
  echo "Acceptable grades are A B C D F WU (eq to F)"

function calc {
  echo `echo "scale=3; $1" | bc`

function gval {
  grade=`echo "$1" | tr [a-z] [A-Z]`
  case $grade in
    A+ ) echo '4.3';;
    A ) echo '4';;
    A- ) echo '3.7';;

    B+ ) echo '3.3';;
    B ) echo '3.00';;
    B- ) echo '2.7';;

    C+ ) echo '2.3';;
    C ) echo '2.0';;
    C- ) echo '1.7';;

    D+ ) echo '1.3';;
    D ) echo '1.0';;
    D- ) echo '0.7';;

    F ) echo '0';;
    WF ) echo '0';;
    WU ) echo '0';;

# check # of arguments. is it even?
let MOD=$#%2
if [ ! $MOD -eq 0 ]; then
elif [ $# -eq 0 ]; then



for ((i=0;i<$n-1;i+=2)); do


  # convert cgrade (C-) to a number
  grade=`gval $cgrade`
  pts=`calc $grade*$creds`

  echo "$creds * $cgrade ($grade) = $pts"

  points=`calc $points+$pts`
  credits=`calc $credits+$creds`

gpa=`calc $points/$credits`
echo "------------"
echo "Total points  = $points"
echo "Total credits = $credits"
echo "------------"
echo "** GPA (pts/crd) = $gpa"
echo "------------"

(Script uses bc as the calculator. Change that in the calc function if you need to.)

I’ll never get used to Bash’s ugly ass syntax. … esac?

I Can’t Live Without My vim Config

I have updated the vim page with my vimrc/gvimrc configs. Instead of repeating myself, I will quote some parts of the page ..

More details and the vim config itself here

I recommend turning backups on if you have them off. I personally hate having the ~ files all over my OS, so I keep them along with the .swp files in 1 backup dir in ~/.vim/

The programming language skeleton stuff will detect what files you are editing and change options in vim by inheriting the specified files which I put in ~/.vim/skeletons and ~/.vim/inherit.

The skeletons are automatically inserted in new files that vim is aware of. For example, in my own config, I have ~/.vim/inherit/c which has all the usual includes and int main() code. When I make a new C file (“gvim hello.c”), the new file begins with the skeleton code already present. Neat huh?

The inherit files can be used to set specific options for each language. This can mean different bindings, whitespace options, themes, etc depending on what language you’re working with, automatically.

See the vim page

What options have helped you the most?

How to Maintain Static Sites with Git & Jekyll

Static sites in this context just means non-database driven sites. Your static site can be an elaborate PHP script or just a few markup and image files. For this I am using Jekyll – A neat Ruby gem that makes your static sites dynamic. It lets you create layouts and embed custom variables in your HTML (this is a “prototype” of the site).

Jekyll tackles all the nuisances involved in creating static pages (I used to add just enough PHP to make a layout). It works by running your prototype through some parsers and outputs plain static HTML/XML (RSS feeds) etc. It’s perfect for lightweight sites that would be impractical on WordPress, like a few static pages of information, landing pages, portfolio/resume pages, and parked domains.

Git takes care of keeping your development (local) and production (remote) environments synced. Git might be a little confusing if you’re learning it with the mindset that it works like Subversion.

I’ll update this post when the guide is done. For now, the following will assume you’re familiar with Jekyll (or at least have an empty file in the prototype directory) and git. This Bash script simplifies creating the remote git repository:

** please read through the code and make sure you know what this does, and what you’re doing. As of now, this is bias towards my own Apache/vhost setup. It’s trivial to edit for your specific needs. You’re using this at your own risk.

(direct link – repogen.sh)

# 04/01/2009 | http://biodegradablegeek.com | GPL 
# You should be in site (NOT public) root (be in same dir as public/ log/ etc)
# proto/ is created and will house the jekyll prototype
# public/ will be the generated static site
# the public/ folder will be REMOVED and regenerated on every push

if [ -z "$1" ]; then
  echo "Usage: ./repogen.sh domain.comn"

# optional. will make it easier to copy/paste cmd to clone repo 

echo "** creating tmp repo"
mkdir proto
cd proto
git init 
git add INITIAL
git commit -a -m "Initial Commit"

echo "** creating bare repo"
cd ..
git clone --bare proto proto.git
mv proto proto.old
git clone proto.git
rm -rf proto.old

echo "** generating hook"

mv $HOOK /tmp
echo '#!/bin/sh' &gt;&gt; $HOOK
echo '# To enable this hook, make this file executable by "chmod +x post-update".' &gt;&gt; $HOOK
echo '#exec git-update-server-info' &gt;&gt; $HOOK
echo '' &gt;&gt; $HOOK
echo '' &gt;&gt; $HOOK
echo 'URL='"$URL" &gt;&gt; $HOOK
echo 'PROTO="/home/$USER/www/$URL/proto"' &gt;&gt; $HOOK
echo 'PUBLIC="/home/$USER/www/$URL/public"' &gt;&gt; $HOOK
echo  '' &gt;&gt; $HOOK
echo 'export GIT_DIR="$PROTO/.git"' &gt;&gt; $HOOK
echo 'pushd $PROTO &gt; /dev/null' &gt;&gt; $HOOK
echo 'git pull' &gt;&gt; $HOOK
echo 'popd &gt; /dev/null' &gt;&gt; $HOOK
echo '' &gt;&gt; $HOOK
echo "echo -----------------------------" &gt;&gt; $HOOK
echo "echo '** Pushing changes to '$URL" &gt;&gt; $HOOK
echo "echo '** Moving current public to /tmp'" &gt;&gt; $HOOK
echo 'mv "$PUBLIC" "/tmp/'$URL'public-`date '+%m%d%Y'`"' &gt;&gt; $HOOK
echo 'echo "** Generating new public"' &gt;&gt; $HOOK
echo 'jekyll "$PROTO" "$PUBLIC"' &gt;&gt; $HOOK

echo "** enabling hook"
chmod a+x $HOOK 

echo "** clone repo on local machina. example:"
echo "git clone ssh://$USER@$SSHURL/~$USER/www/$SSHURL/proto.git"


Your site structure might be different. repogen.sh is made by pasting the above code in a new file, and then chmod a+x to make it executable. This should be done on the remote server.

cd www/domain.com/
public/ private/ log/ cgi-bin/

./repogen.sh domain.com

Now on your local machine, clone the new repo, move your files in, and push:

git clone ssh://[username]@ssh.domain.com/~[username]/www/domain.com/proto.git
cd proto/
cat "hello, world" &gt; index.htm
git add index.htm
git commit -a -m 'first local commit'
git push

After you push your changes, the post-update hook will delete the public/ directory (the root of the site). This dir and its contents are automatically generated and will get wiped out on EVERY push. Keep this in mind. All your changes and content should reside in proto/.

The proto/ repo will pull in the new changes, and then Jekyll will be invoked to generate the updated site in public/ from the prototype.

Should you need to edit it, the post-update hook is in the bare git repo (proto.git/hooks/)

Thanks to the authors in the posts below for sharing ideas. I first read this git method on dmiessler’s site.

dmiessler.com – using git to maintain static pages
toroid.org – using git to manage a web site
Jekyll @ GitHub
git info
more git info

Multiple Monitors vs One Big Screen

Most people I know who’ve never used dual screen ask me why I don’t invest in one big monitor instead. There’s a big difference between having multiple monitors and having just one, no matter the size. Though which is better really depends on what you’re using the computer for, what OS/window manager you’re using, and how you use your particular setup.

For programming, and the way I use my desktop (gnome+compiz), having multiple screens is much more productive than one big screen because I hate minimizing and dragging windows. If I’m coding in rails for example, I can have my editor maximized in one screen, and a reference window or a `tail -f file.log` maximized in the other screen. With a big monitor I would need to manually resize each window or depend on my window managers cascade feature, which requires some manual resizing as well.

For coding or writing, a killer setup would be having two or three widescreen displays setup vertically side-by-side. I noticed I only look at 3/4th of the screen real estate when I’m coding, and when I hack or write, Continue reading Multiple Monitors vs One Big Screen

Script to Quickly Setup WebApp Environment and Domain

Just sharing a script I wrote to quickly deploy WordPress (and eventually a few other webapps) sites, which somebody might find useful. This uses Linode‘s API* to add the domain name to the DNS server along with some subdomains. If you’re using another server, (Slicehost, your own, etc), you can alter the dns class to use that API, or just ignore the DNS stuff completely; Its optional.

This will be updated periodically as I refactor and add support for more apps (notably Joomla and Clipshare – though this would violate their terms unless you have the unlimited license). This was written primarily because I couldn’t stand setting up another vhost and WordPress installation. There are plenty of existing deployers but I plan on adding very specific features and tweaking this for in-house work. I also wanted to try Rio (Ruby-IO). GPL license. Go nuts.

* As of 10/11, the apicore.rb file on the site has some syntactic errors in the domainResourceSave method. I sent an email out to the author about it. Problems aren’t major. You can get my apicore.rb here.

This won’t run unless you create the appropriate folder structure in /etc/mksite/. I’ll get going on this in a bit. See the code below:

Continue reading Script to Quickly Setup WebApp Environment and Domain

How To Use Fixtures to Populate Your Database in Rails

UPDATE: I’ve been using this method for awhile now: http://railspikes.com/2008/2/1/loading-seed-data

Seed data is data that the app is dependent on. It is data that has to exist if you were to wipe the database clean and reload your schema. Some examples would be a list of cities/states, a list of categories, or the initial ‘admin’ user account.

Most people looking at this thread want seed data rather than to populate their database with test/generated content. For the latter, you can go the route below or try Forgery

This is a response to the email I’ve been getting asking me how to use fixtures to load data into a database.

You want to create dummy entries in your Rails app, either for testing, for development, or for production, to make your site appear popular. Whatever the reason, populating your database can be done easily using fixtures.

While rake/fixtures/migrations can get a lot more complex, this will be a brief introductory example.

Initial App setup

$ rails characters
$ cd characters/

Edit config/database.yml – We only need a development database. So open up PHPMyAdmin or the MySQL command shell and:

mysql> CREATE database characters_development;
Query OK, 1 row affected (0.00 sec)

(I’m assuming you’re using MySQL. You can use anything; SQLite, Postgres, etc..)

Create a model and a table in the database (using a migration)

$ script/generate model Character
      exists  app/models/
      exists  test/unit/
      exists  test/fixtures/
      create  app/models/character.rb

$ vim db/migrate/001_create_characters.rb

Sexy migration:

class CreateCharacters < ActiveRecord::Migration
  def self.up
    create_table :characters do |t|
      t.string  :name, :alias, :motto

  def self.down
    drop_table :characters

Now migrate development (default environment):

$ rake db:migrate

Create the characters fixture

$ vim test/fixtures/characters.yml

Continue reading How To Use Fixtures to Populate Your Database in Rails

How to POST Form Data Using Ruby

POSTing data on web forms is essential for writing tools and services that interact with resources already available on the web. You can grab information from your Gmail account, add a new thread to a forum from your own app, etc.

The following is a brief example on how this can be done in Ruby using Net::HTTPand this POST form example.

Looking at the source (interlacken.com/webdbdev/ch05/formpost.asp):

<form method="POST" action="formpost.asp">
<p><input type="text" name="box1″ size="20″ value="">
<input type="submit" value="Submit" name="button1″></p>

We see two attributes are sent to the formpost.asp script when the user hits the submit button: A textbox named box1 and the value of the submit button, named Submit. If this form used a GET method, we would just fetch the URL postfixed with (for example) ?box1=our+text+here. Fortunately, Ruby’s Net::HTTP makes posting data just as easy.

The Ruby code:


require "uri"
require "net/http"

params = {'box1′ => 'Nothing is less important than which fork you use. Etiquette is the science of living. It embraces everything. It is ethics. It is honor. -Emily Post',
'button1′ => 'Submit'
x = Net::HTTP.post_form(URI.parse('http://www.interlacken.com/webdbdev/ch05/formpost.asp'), params)
puts x.body

# Uncomment this if you want output in a file
# File.open('out.htm', 'w') { |f| f.write x.body }

Sending the value of button1 is optional in this case, but sometimes this value is checked in the server side script. One example is when the coder wants to find out if the form has been submitted – as opposed to it being the user’s first visit to the form – without creating a hidden attribute to send along w/ the other form fields. Besides, there’s no harm in sending a few more bytes.

If you’re curious about URI.parse, it simply makes the URI easier to work with by separating and classifying each of its attributes, effectively letting the methods in Net::HTTP do their sole job only, instead of having to analyze and parse the URL. More info on this in the Ruby doc.

Assuming no errors, running this example (ruby postpost or chmod a+x postpost.rb; ./postpost.rb) yields:

<form method="POST" action="formpost.asp">
<p><input type="text" name="box1″ size="20″ value="NOTHING IS LESS
<input type="submit" value="Submit" name="button1″></p>

In practice, you might want to use a more specialized library to handle what you’re doing. Be sure to check out Mechanize and Rest-client.

GitHub Now Open to the Public

GitHub.com, the “easiest (and prettiest)” version control system, is now open to the public. It’s free for Open Source programs (albeit limited to 100MB of space).

If you’re not sure what git (or Revision Control) is, here are some resources:
Wikipedia on Revision Control

(excerpt) “Revision control (also known as version control (system) (VCS), source control or (source) code management (SCM)) is the management of multiple revisions of the same unit of information. It is most commonly used in engineering and software development to manage ongoing development of digital documents like application source code, art resources such as blueprints or electronic models, and other critical information that may be worked on by a team of people. Changes to these documents are usually identified by incrementing an associated number or letter code, termed the ‘revision number’, ‘revision level’, or simply “revision” and associated historically with the person making the change. A simple form of revision control, for example, has the initial issue of a drawing assigned the revision number ‘1’. When the first change is made, the revision number is incremented to ‘2’ and so on.”

(A cocky) Linus Torvalds talking on git:

Flame On!

Subversion vs git vs other?
Flame Control System

Introduction to Validations & Validation Error Handling in Rails

Purple Nitraguard Security Keypad

Validations in Ruby on Rails are essentially nothing more than methods that ensure that the data in a model is valid before saving it to the database. Traditionally, we validate data coming in using conditional expressions (for example, if email != NULL or if passwd==passwd_confirmation). This task is essential, but boring and tedious, but Rails’ validations make this mundane part of programming as simple and as easy as possible. The validations provided in Rails (defined in every model) are thorough, likely covering all your needs right out of the box. There are even validations provided for checking whether a user agreed to a Terms of Service or End-User License Agreement (EULA), and for doing automatic field confirmation, useful when you ask the user for an email or password twice to ensure no misspelling.
Continue reading Introduction to Validations & Validation Error Handling in Rails