semind

readelf -a hoge.elf

semind

see http://guides.rubyonrails.org/3_2_release_notes.html

This makes it possible to write the following:


class Order < ActiveRecord::Base
  def cancel!
    transaction do
      lock!
      # ... cancelling logic

semind

### 2TB以上のHDDを使う場合。partedコマンドでMBRではなくGPTを利用するようにする。

ex) 3TBのディスクの場合
# parted /dev/XXX
(parted) mklabel gpt
(parted) mkpart                                                           
Partition name?  []?                                                      
File system type?  [ext2]? ext4                                           
Start? 1                                                                  
End? 3001GB

semind

### デフォルトで使えるパラメータ
node['platform'] - The node's platform. This determines what Providers are used by Resources.
node['platform_version'] - The node's platform version. This may be used in determining Providers as well.
node['ipaddress'] - The node's ipaddress is IPV4 address of the interface that has the default route. If the node does not have a default route, this attribute will be nil. Using the IP of the interface with the default route is deemed the most sane default.
node['macaddress'] - The node's macaddress, from the interface detected for ipaddress above.
node['fqdn'] - The fully qualified domain name, for example from hostname -f on Unix/Linux systems. This is also used as the node name unless otherwise set.
node['hostname'] - The hostname is the first field from splitting the FQDN on "." (dot).
node['domain'] - The domain is the rest of the FQDN after splitting on "." (dot).
node['recipes'] - The node's Run List is expanded for roles and recipes, and recipes are stored in this attribute.
node['rol

semind

#////////// Arel ///////////

### whereを使って完全一致の比較を行う ###
Model.where(:column => param)

### Arelは常に結果を配列で返すようなので一つだけとりだしたい場合(ユニークキーで検索する時とか)は.firstを使うと良い ###
Model.where(:column => param).first

### whereを使って大小の比較を行う ###
Model.where('column > param')

semind

### 配列の中身を個々の変数に分割して代入
test = ['a', 'b', 'c']
test << 'd'
p test  # => ["a", "b", "c", "d"]

### ファイルからの相対パスでライブラリを読み込むためのイディオム
# $:は$LOAD_PATHと等価
$:.unshift(File.dirname(__FILE__))
$:.unshift(File.dirname(__FILE__) + "/lib")

semind

##### nginxでリバースプロキシして後段でエラーが発生した場合にnginx側でエラーページの制御をしたい時の設定 #####
proxy_intercept_errors on;  # errorをproxy側で肩代わりする設定
error_page 403 404 500 502 503 504  /error.html; # /var/www/html/error.htmlを置いておく

location /error.html {
    root /var/www/html/;
}

#### headerの値を参照する ####
$http_フィールド名