= 2010-05-30 =

 * [專案] '''[wiki:jazz/ClassCloud_LiveCD ClassCloud-LiveCD : 基於 DRBL 的雲端教學環境] '''

== DRBL-Hadoop Live ==

 * 如何在 shell script 裡面安裝 java 又不用選 yes
   * [參考] [http://www.davidpashley.com/blog/debian/java-license Installing java non-interactively]
   * 這裡提到用 debconf-set-selections 來設定一些參數，讓 sun-java*-* 不問授權的 yes，方法包括有寫檔跟沒寫檔的做法，個人覺得留言裡面的那個做法最帥了!!
{{{
cat << EOF | /usr/bin/debconf-set-selections
sun-java6-bin   shared/accepted-sun-dlj-v1-1    select true
sun-java6-jdk   shared/accepted-sun-dlj-v1-1    select true
sun-java6-jre   shared/accepted-sun-dlj-v1-1    select true
EOF
}}}
   * 那麼如果以後遇到別的套件也有類似的問題該怎麼找參數呢?? 答案是用 debconf-get-selections 這個指令，首先必須安裝 [http://packages.debian.org/debconf-utils debconf-utils] 套件，然後執行 debconf-get-selections 再用 grep 用套件名稱找出可以改的參數。
{{{
~$ sudo debconf-get-selections | grep sun-java6
sun-java6-jre	sun-java6-jre/stopthread	boolean	true
sun-java6-bin	shared/accepted-sun-dlj-v1-1	boolean	true
sun-java6-jre	shared/accepted-sun-dlj-v1-1	boolean	true
sun-java6-jre	sun-java6-jre/jcepolicy	note	
sun-java6-bin	shared/error-sun-dlj-v1-1	error	
sun-java6-jre	shared/error-sun-dlj-v1-1	error	
sun-java6-bin	shared/present-sun-dlj-v1-1	note	
sun-java6-jre	shared/present-sun-dlj-v1-1	note	
}}}
   * 須注意的是原本參數是 boolean 格式，若要下給 debconf-set-selections 必須置換成 select 關鍵字喔!!
{{{
~$ sudo debconf-get-selections | grep sun-java6 | grep boolean | sed 's#boolean#select#g'
sun-java6-bin   shared/accepted-sun-dlj-v1-1    select  true
sun-java6-jdk   shared/accepted-sun-dlj-v1-1    select  true
sun-java6-jre   shared/accepted-sun-dlj-v1-1    select  true
sun-java6-jre   sun-java6-jre/stopthread        select  true
}}}

== Shell Script ==

 * 如何在 shell script 裡面把標準輸入跟標準輸出重新導向到另一個路徑呢?!
   * [參考] [http://www.linuxquestions.org/questions/linux-general-1/shell-scripting-how-to-redirect-output-from-within-the-script-itself-446558/ Shell scripting: How to redirect output from within the script itself? ]
{{{
#!sh
#! /bin/bash

TARGET="target-file"

# file descriptor 4 prints to STDOUT and to TARGET
exec 4> >(while read a; do echo $a; echo $a >>$TARGET; done)
# file descriptor 5 remembers STDOUT
exec 5>&1

# now STDOUT is redirected
exec >&4
date

# wer're done
exec >&5
echo "Date sent to fd4."
}}}