Technical Notes and Stuff Happening

First post of 2010

2010-03-13T00:19:00.001-08:00

Just because I haven't done it in awhile.

Give me a function that given a line, describes the next

2009-08-04T18:20:00.000-07:00

1
11
21
1211
111221
312211
13112221
1113213211

char* get_next_line(char* line)
{
char next_line[4096];
int next_line_ndx = 0;

char letter = line[0];
int num_letters = 0;

for (int i = 0; i < strlen(line); ++i)
{
if (letter != line[i+1])
{
next_line[next_line_ndx] = num_letters + '0';
next_line_ndx++;
next_line[next_line_ndx] = letter;
next_line_ndx++;
next_line[next_line_ndx] = 0;

letter = line[i+1];
num_letters = 0;
}
else
{
num_letters++;
}
}

return next_line;
}

breadth first search of binary tree (w/o the formatting)

2009-07-29T09:15:00.000-07:00

7
/ \
1 2
/ \ /
0 3 4
\
2

7
1 2
0 3 4
2

def traverse_tree(node):
q = []
last_level = 0
current_level = 0
q.append([node, current_level])

while len(q) > 0:
node, current_level = q.pop()

if current_level != last_level:
last_level = current_level
print "\n"
print node + " "

left_child = node.left
right_child = node.right

if left_child not NULL:
q.append([left_child, current_level + 1])

if right_child not NULL:
q.append([right_child, current_level + 1])

MySQL restart on Mac OS X

2008-10-20T14:25:00.000-07:00

This is the simplest way to restart the server on Mac OSX that I found

my-computer:~ me$ mysqladmin -uroot -p shutdown
Enter password:
my-computer:~ me$ sudo mysqld_safe
Starting mysqld daemon with databases from /sw/var/mysql

Voted

2008-10-16T14:58:00.001-07:00

I voted so I have the right to complain.

MySQL Python API

2008-10-08T09:50:00.000-07:00

If you try to install the python API for MySQL on Leopard, and receive the following message:

lipo: can't open input file: /var/tmp//ccDsRjet.out (No such file or directory)

make sure you check out this.

Nice Macports explanation for Ruby Rails

2008-06-09T01:29:00.000-07:00

http://paulsturgess.co.uk/articles/show/46-using-macportsdarwinports-to-install-ruby-on-rails-mysql-subversion-capistrano-and-mongrel-on-mac-os-x

Installing BerkeleyDB perl module from CPAN

2008-06-06T08:28:00.000-07:00

I was getting an error executing:

cpan -i BerkeleyDB

This seemed to be because I did not have Berkeley installed on my mac. Well no problem, just execute

port install db46

from Macports. After that finishes, just set up a link in /usr/local e.g.

ln -s /usr/local/BerkeleyDB.4.6/ /usr/local/BerkeleyDB

and then

cpan -i BerkeleyDB

should work.

Install perl module off cpan

2008-06-06T07:22:00.000-07:00

it's easy

cpan -i [module]

Enable sending email on Mac OS X

2008-06-03T02:33:00.000-07:00

It wasn't completely obvious to me, but here is what you need to execute in order to be able to send email from your Mac.

in a terminal:

postfix start

Installing and setting up a fink installed MySQL with a non-default data directory

2008-05-28T04:59:00.000-07:00

So I assume you have successfully executed: sudo fink install mysql

Create or edit /etc/my.cnf and add or change the keyword datadir to the directory you want e.g.

[mysqld]

datadir=/Volumes/another/directory

[mysqld_safe]

datadir=/Volumes/another/directory

During installation, Fink set up some files and directories in /sw/var/mysql. Copy the contents of this directory to your new directory e.g.

sudo cp -r /sw/var/mysql/* /Volumes/another/directory

Go to /Volumes/another/directory and set the owner of all contents to mysql e.g.

sudo chown -R mysql /Volumes/another/directory.

At this point you should be able to run 'sudo mysqld_safe.'

fink Mysql on Macbook OSX 10.5 leopard

2008-05-17T05:45:00.000-07:00

I installed mysql from fink and received some unwelcome news.

My-MacBook:~ me$ sudo mysqld_safe
Password:
chown: mysql: Invalid argument
Starting mysqld daemon with databases from /sw/var/mysql
STOPPING server from pid file /sw/var/mysql/My-MacBook.local.pid
080517 14:39:45 mysqld ended

After looking at /sw/var/mysql/My-MacBook.local.err, it seemed I was missing the user mysql. So I snooped around google and found the answer. Based on this, I executed the following commands:

sudo dscl localhost -create /Local/Default/Users/mysql

sudo dscl localhost -create /Local/Default/Users/mysql NFSHomeDirectory /var/empty
sudo dscl localhost -create /Local/Default/Users/mysql Password '*'
sudo dscl localhost -create /Local/Default/Users/mysql PrimaryGroupID 74
sudo dscl localhost -create /Local/Default/Users/mysql RealName "MySQL Server"
sudo dscl localhost -create /Local/Default/Users/mysql UniqueID: 74
sudo dscl localhost -create /Local/Default/Users/mysql UserShell: /usr/bin/false

My next attempt to start mysqld_safe gave me some more bad news:

My-MacBook:var me$ sudo mysqld_safe Password:
chown: mysql: Invalid argument
Starting mysqld daemon with databases from /sw/var/mysql
STOPPING server from pid file /sw/var/mysql/My-MacBook.local.pid
080517 17:11:24 mysqld ended

This one was easy though. Just go to /sw/var and execute chown -R mysql mysql. You should be good to go from here. sudo mysqld_safe& should work just fine.

Adobe Flex license key Leopard OSX

2008-05-14T11:24:00.000-07:00

If you ever receive a message like "License key is invalid" when you enter in your valid license
for Adobe Flex on OSX, try switching to an admin account. For some reason when you enter the license key into Flex Builder (or the Eclipse plug-in) under a non-admin account, you cannot 'activate' the installation.

gem install mysql mac osx leopard

2008-05-10T06:08:00.001-07:00

gem install mysql -- --with-mysql-config=`which mysql_config`

Also you may need some additional hacking to get it all working.

Updating locate on Mac OSX

2008-03-19T05:15:00.001-07:00

Update locatedb on your Mac OSX with:
sudo /usr/libexec/locate.updatedb

Debugging ruby rails in production

2008-03-11T05:58:00.001-07:00

Helpful little thing that helped me debug my ruby rails production system.

shell$ [RAILS_ROOT]/script/console production

So here you can invoke a model (e.g. User.new), call helper methods (UserHelper.authenticate(user, pass)), etc.

Ruby Rails column type to MySQL datatype

2008-03-06T05:04:00.000-08:00

lifted from PackT.

Migration column type...	Converts to MySQL field type...	Available options1
:binary	TINYBLOB, BLOB, MEDIUMBLOB, or LONGBLOB2	:limit => 1 to 4294967296 (default = 65536)2
:boolean	TINYINT(1)	-
:date	DATE	-
:datetime	DATETIME	-
:decimal	DECIMAL	:precision => 1 to 63 (default = 10) :scale => 0 to 30 (default = 0)3
:float	FLOAT	-
:integer	INT	:limit => 1 to 11 (default = 11)
:primary_key	INT(11) AUTO_INCREMENT PRIMARY KEY	-
:string	VARCHAR	:limit => 1 to 255 (default = 255)
:text	TINYTEXT, TEXT, MEDIUMTEXT, or LONGTEXT2	:limit => 1 to 4294967296 (default = 65536)2
:time	TIME	-
:timestamp	DATETIME	-

Production Rails Database

2008-03-04T03:43:00.001-08:00

To make a production version of a database defined in rails.

rake db:migrate RAILS_ENV="production"

phpMyAdmin plug

2008-03-03T01:31:00.001-08:00

Man... gotta use phpMyAdmin for looking at your MySQL database. On Mac use 'Fink Commander' and look for phpMyAdmin. Follow the configuration instructions here. In order for me to get it working, I had to set the following properties:

$cfg['Servers'][$i]['socket'] = '/tmp/mysql.sock';
$cfg['Servers'][$i]['connect_type'] = 'socket';

Instance variable in viewer for ActionMailer

2008-02-26T01:08:00.001-08:00

Using the ActionMailer in your Ruby on Rails application, I wanted to display a variable in the viewer. If the content_type is "text/html", the body needs to have the instance variable symbol e.g. body :var => var. In the viewer, you may reference this variable with <%= @var %>.

svn checkout url

2008-02-14T01:00:00.001-08:00

For some reason, I always have a tough time remembering how to check out code from an svn repository. So here it goes:

svn co svn+ssh://[user]@[server]/[path to project on svn server]

Sharing OSX leopard folder and mounting it on Windows XP

2008-02-10T08:55:00.000-08:00

So it shouldn't be that hard, but it took me about half an hour so I got to document it. I tried mounting a folder shared on my Leopard from an XP machine. This is finally how I got it done:

On Leopard:

In System Preferences, under Network, tab over to WINS and set the Workgroup to something like 'Mshome'
In System Preferences, under Sharing, click options and check 'Share files and folders under SMB'

On Windows:

Right click on 'My Computer', clicking on 'Map Network Drive'
Click 'Browse', and you should see your Mac (for some reason your XP might not see the Mac right away, wait about 5 minutes)

Simple exporting of MySQL tables into a file

2008-02-06T01:11:00.000-08:00

echo "select * from [table];" | mysql -u[user] -h[server] -p[password] [database] > [output_file]

Simple Ruby MySQL

2008-02-01T05:56:00.000-08:00

To get the MySQL Ruby library to work as documented on troubleshooters, I had to add the following require statement:

require 'rubygems'
require 'mysql'
.
.
.
mysql.close()

Nuovi Anni a Torino, Italia

2008-01-20T01:17:00.000-08:00

Yea.... still keeping it real at Piazza San Carlo in Torino, Italia on New Year's eve.

Ruby Captcha

2008-01-17T01:00:00.000-08:00

So I wanted to get a captcha rolling in Ruby on Rails. I decided to use recaptcha because Luis's research is so cool. The tutorial for Ruby recaptcha is fine, but I would have liked an explicit example of what would be in environment.rb.

Rails::Initializer.run do |config|
...
RCC_PUB = '...' #Public key from recaptcha registration
RCC_PRIV = '...' #Private key from recaptcha registration
end

Finally, I had to restart Webrick for those variables to take effect.

Installing Mongrel on a Linux box

2008-01-17T00:27:00.000-08:00

So I wanted to run Mongrel on a linux box in which I did not have root authority.

My configuration

ruby 1.8.5 (2006-08-25) [i386-linux]
gem version 0.9.4

Simply run:

gem install mongrel -i [dir_you_can write_to] (You may have to run this twice if the first invocation gives an error)

You will see something like:
Select which gem to install for your platform (i386-linux)
1. mongrel 1.1.3 (java)
2. mongrel 1.1.3 (i386-mswin32)
3. mongrel 1.1.3 (ruby)
4. mongrel 1.1.2 (ruby)
5. mongrel 1.1.2 (mswin32)
6. mongrel 1.1.2 (java)
7. Skip this gem
8. Cancel installation

I picked 3.  Hopefully this works with out a problem.

You will also need:
gem install rails -i [dir_you_can write_to]

In the [dir_you_can write_to], you will find bin/mongrel_rails.
Go to your directory containing the rails application and run 
[dir_you_can write_to]/bin/mongrel_rails.
After invoking this, I received the following error message:
/usr/lib/ruby/site_ruby/1.8/rubygems.rb:303:in `report_activate_error': Could not find RubyGem mongrel (> 0) (Gem::LoadError)
  from /usr/lib/ruby/site_ruby/1.8/rubygems.rb:237:in `activate'
  from /usr/lib/ruby/site_ruby/1.8/rubygems.rb:75:in `active_gem_with_options'
  from /usr/lib/ruby/site_ruby/1.8/rubygems.rb:49:in `gem'
  ...

The solution for this is to set GEM_PATH like so:
export GEM_PATH=/non_default_gems_install/ruby_gems

Try running this again
[dir_you_can write_to]/bin/mongrel_rails start -p 8000

Open a browser pointing it to server:8000 should display the rails application.

Getting Ruby on Rails up and running in Eclipse

2008-01-16T11:53:00.000-08:00

So I'm running on a MacBook running Leopard and wanted to do some Ruby on Rails development using Eclipse. Here is what I did.

Follow the tutorial for installing the base libraries for the following components

Ruby
RubyGems
Ruby on Rails
FastCGI
You will need MySQL, but this tutorial is OSX specific
MySQL Native Bindings

Download and install Eclipse.
Open Eclipse and install the following plugins.

Aptana plugin
Ruby Development Tools plugin (pick the release version) (OPTIONAL as of 6/9/2008)
Subclipse plugin
Somewhere in the process I ran into a problem involving Mylyn. Well go ahead and install that as well.

Open Eclipse, open the Help drop down and click on Aptana Start Page. In the center column you will see the Aptana Ruby on Rails plugin. Go ahead and install it.
Now you should easily be able to create a Rails project within Eclipse.