[RPi] Raspberry Pi ARM based bare metal examples

control low-level peripherals of Raspberry Pi directly without operating system, see this repo

[PHP] PHP UTF-8 cheatsheet

要確認PHP的輸出是否為UTF-8,有許多步驟要檢查,不過已經有人整理好了,順便筆記一下吧:

1. Update your database tables to use UTF-8

CREATE DATABASE db_name
 CHARACTER SET utf8
 DEFAULT CHARACTER SET utf8
 COLLATE utf8_general_ci
 DEFAULT COLLATE utf8_general_ci
 ;

ALTER DATABASE db_name
 CHARACTER SET utf8
 DEFAULT CHARACTER SET utf8
 COLLATE utf8_general_ci
 DEFAULT COLLATE utf8_general_ci
 ;

ALTER TABLE tbl_name
 DEFAULT CHARACTER SET utf8
 COLLATE utf8_general_ci
 ;

2. Install the mbstring extension for PHP

3. Configure mbstring

$ vim /path/to/php.ini

mbstring.language             = Neutral ; Set default language to Neutral(UTF-8) (default)
mbstring.internal_encoding    = UTF-8  ; Set default internal encoding to UTF-8
mbstring.encoding_translation = On  ;  HTTP input encoding translation is enabled
mbstring.http_input           = auto  ; Set HTTP input character set dectection to auto
mbstring.http_output          = UTF-8  ; Set HTTP output encoding to UTF-8
mbstring.detect_order         = auto  ; Set default character encoding detection order to auto
mbstring.substitute_character = none  ; Do not print invalid characters
default_charset               = UTF-8  ; Default character set for auto content type header

4. Deal with non-multibyte-safe functions in PHP

$ vim /path/to/php.ini

mbstring.func_overload = 7 ; All non-multibyte-safe functions are overloaded with the mbstring alternatives

change functions

mail()          -> mb_send_mail()
strlen()        -> mb_strlen() 
strpos()        -> mb_strpos()
strrpos()       -> mb_strrpos()
substr()        -> mb_substr()
strtolower()    -> mb_strtolower()
strtoupper()    -> mb_strtoupper()
substr_count()  -> mb_substr_count()
ereg()          -> mb_ereg()
eregi()         -> mb_eregi()
ereg_replace()  -> mb_ereg_replace()
eregi_replace() -> mb_eregi_replace() 
split()         -> mb_split()

5. Sort out HTML entities
add wrapper

/**
 * Encodes HTML safely for UTF-8. Use instead of htmlentities.
 *
 * @param string $var
 * @return string
 */
function html_encode($var)
{
 return htmlentities($var, ENT_QUOTES, 'UTF-8') ;
}

6. Check content-type headers
modify output

header('Content-type: text/html; charset=UTF-8') ;

and

<meta http-equiv="Content-type" value="text/html; charset=UTF-8" />

7. Update email scripts
use UTF-8 encoding in text file, and mb_encode_mimeheader() with content

8. Check binary files and strings


reference:
* PHP UTF-8 cheatsheet

[Tips] dpkg指令快速參考

Debian/Ubuntu系列相關都使用dpkg(Debian package management system)做為軟體管理系統,常用到的指令筆記一下

dpkg -i package.deb     # install
dpkg -r package         # remove
dpkg -P package         # purge, including configuration
dpkg -L package         # listfiles
dpkg -l package         # list package concisely
dpkg -S keyword         # find package(s) owning file(s)
dpkg -l                 # list installed package
dpkg -c package.deb     # listfiles                  

[Tips] Switch to External Monitor in LXDE

之前換了國人自製的LXDE,發現有些設定不太一樣,比如說想要將螢幕投到外接螢幕,function按鍵就沒作用,非要重開機才能正常,爬了一下文才發現原來LXDE還有做這樣的螢幕管理工具,說明如下:

Description: simple monitor config tool for LXDE This is a very basic monitor config tool utilizing the X extension called RandR. It can let you change the screen resolution on the fly. Besides, when you run lxrandr with external monitor connected, its GUI will change, and show you some quick options to get your projector or external monitor working correctly.

執行方式就是直接呼叫

$ sudo lxrandr

預設執行起來應該是這樣

如果有外接螢幕就會變成這樣

選擇正確的輸出就可以快樂的投影了