Eric Guo's

in HTML5, JavaScript, Ruby & Rails, Python, and Cloud MES!

Resolve New RVM 1.26 GPG Key Import Failure Problem


When the hkp port blocked, so rvm suggested gpg --keyserver hkp:// --recv-keys D39DC0E3 always failed to running, here is how to resolve such problem.

  1. Find a hkp port not block server, run export after import the key:

    gpg --keyserver hkp:// --recv-keys D39DC0E3 gpg --export --armor D39DC0E3

  2. Go to hkp port blocked server, run:

    gpg --import -

and copy and paste the step 1 server public key content and press Ctrl+D

Another option you can try is using port 80, but it’s can not always work.

apt-key adv --keyserver hkp:// --recv 561F9B9CAC40B2F7

Compile Eventmachine 1.0.3 in Ruby 2.1.3 on Windows


eventmachine didn’t release a new gems for a long time, so we have to manually compile if you decide using Ruby 2.1.3, it’s probably the most complex gems which can still successfully install on windows as far as I known, here is the steps for your interesting:

git clone
cd eventmachine && bundle install

Now you will meet the bluecloth can not install problem first, which you can following stackoverflow steps including patch ext/bluecloth.h and 6 steps.

Now you need using updated version of rake-compiler (v0.9.3) to continue, so change eventmachine.gemspec to that version and do the bundle install again.

Now we can running rake package and it should generate the updated 1.0.3 gem file you need, but before that you need another depend lzma package mentioned in Ruby Installer Google Group, I only tested x86 but the x64 should be same.

  1. Put the download openssl-1.0.0m-x86-windows.tar.lzma to c:\temp
  2. run C:\DevKit\devkitvars.bat
  3. c:\Temp> bsdtar --lzma -xf openssl-1.0.0m-x86-windows.tar.lzma
  4. c:\git\eventmachine\pkg> gem install ./eventmachine-1.0.3.gem --platform=ruby -- --with-opt-dir=C:/Temp

Now enjoy eventmachine on ruby 2.1.3 windows!

Checking Gem Reverse Dependencies


gem dependency parser --reverse-dependencies or -R in short only works in local, so if you want to get all gems from rubygems, can using:

ruby -ropen-uri -rpp -ryaml -e 'pp YAML.load(open(""))'

The tip is coming from Faria DevTips.

Installation Ruby 2.1.3 on Windows Log


Except simply install the ruby 2.1.3 from rubyinstaller and it’s DevKit, here is my log when I meet the problem during ruby 2.1.3 on a Windows 7 32bits machine.

  1. Comments out the warn “DL is deprecated, please use Fiddle” at C:\Ruby21\lib\ruby\2.1.0\dl.rb
  2. Install yajl-ruby via gem install yajl-ruby -v 1.1.0 --platform ruby
  3. Install RedCloth via gem install RedCloth --platform ruby and move the file C:\Ruby21\lib\ruby\gems\2.1.0\gems\RedCloth-4.2.9\lib\ to new created folder C:\Ruby21\lib\ruby\gems\2.1.0\gems\RedCloth-4.2.9\lib\2.1.
  4. Install sqlite3 via:

    1. run C:\DevKit\devkitvars.bat
    2. mkdir c:\temp
    3. download to c:\temp
    4. c:\Temp>bsdtar --lzma -xf sqlite-
    5. c:\Temp>gem install sqlite3 --platform=ruby -- --with-opt-dir=C:/Temp
  5. Install bcrypt via gem install bcrypt --platform ruby

  6. Install win32console via gem install win32console --platform ruby

  7. Install ffi via gem install ffi --platform ruby

  8. Install pg via gem install pg --platform ruby

  9. Install mysql following stackoverflow via gem install mysql2 --platform=ruby -- '--with-mysql-dir="C:\mysql-connector"'

  10. Install puma via gem install puma -- --with-opt-dir=c:\temp

Setting global environment setting:


Also do not using ansicon in ruby 2.1.3 any more, seems not compatible.

How to Install Gem Curb in Windows


After read the post in Ruby-China say how to use mechanize and curl to login Ruby-China, I decide to install curb, seems still a little tricky.

First download last available libcurl in windows, which currently is 7.40.0.

Notice most up-to-date version curl-7.47.1-win32-mingw not working, so still using 7.40.0.

Extract to C:\ and install the curb via below command.

gem install curb --platform=ruby -- --with-curl-lib=C:/curl-7.40.0-devel-mingw32/bin --with-curl-include=C:/curl-7.40.0-devel-mingw32/include

Some relative issues in github about curb, #37, #183

To make SSL certification work, you need to set your windows environment variable, the file can be download here


Finally, need copy all DLL and EXE file in C:\curl-7.40.0-devel-mingw32\bin to C:\Ruby200\bin.

Unlock the Locked Table by Kill Session


Seems I frequently need to kill some session due to the network issue or other client issue to submit data to oracle, but each time I google the answner, it takes me at least 5 minutes, so I decide to write done SQL and command here:

Find the locked session
SELECT a.sid,a.serial#, a.username,c.os_user_name,a.terminal,
b.object_id,substr(b.object_name,1,40) object_name
from v$session a, dba_objects b, v$locked_object c
where a.sid = c.session_id
and b.object_id = c.object_id
Kill session
alter system kill session '14,397';

Postback Other Input Controls Value in Rails Jquery-ujs Data-remote Request


The Unobtrusive JavaScript feature introduce from Rails 3.1 and the Rails Guide have a whole chapter to say about how to use, but the jquery-ujs much more feature not talked in official Rails Guide.

Except the AJAX forms and some link_to feature, one of my favorite features is AJAX HTTP request back to server when one of the forms input control content changed by user and lost focus. Such feature is very similar to ASP.NET AutoPostBack, which is very handy when you need user fill some content first before you can help them auto fill the rest.