Bugs and Tips found recently

1: Teensy as a keyboard does not work properly in GRUB.

Solution: break your long input into parts (<=3 chars) and add delays (50ms is enough) between them.


2: In Debian and Ubuntu, your may install some PHP PECL modules just by using

sudo apt-get install php5-pecl-http php5-propro php5-raphf

(PHP run as an apache mod)

Restart Apache, php -m does not show any new module installed.

Try add ini files(propro.ini File Content: extension=propro.so) to /etc/php5/mod-available and make link (15-propro.ini for example) at /etc/php5/apache/conf.d pointing to /etc/php5/mod-available/propro.ini

restart Apache again, php module still not loading.

The solution:

use php5enmod propro instead :)
3: Dell PowerEdge RAID Controller (PERC) H730 and SSD.
Unable to build raid for Samsung 850 EVO SSD in the Lifecycle Manager.

Solution: goto BIOS and find device management- raid controller then build your RAID there.

My note on Installing OpenWRT on Banana Pi R1 (BPi-R1)

Today, I just got my Banana Pi R1.  Here is a simple guide to set it up as an OpenWRT router.

Step 1: Flash the TF(microSD) card.

  • Goto the download page of BPi-R1 (http://www.bananapi.com/index.php/download?layout=edit&id=65)
  • Find and download the latest OpenWRT Image, which is version 4.0 (01/09/2015) as I write this.
  • Write the OpenWRT image to the TF card. I use OS X, here is the code I used in Terminal:
  • Find the disk number of your TF card. Mine is disk2[Bold number may varies on your computer, wrong number will cause serious problem, you will lose your data on the wrong disk]:
    diskutil list

    Unmount it:

    diskutil unmountDisk /dev/disk<strong>2</strong>

    Write the image:

    sudo dd bs=1m if=~/Downloads/BPI-R1_OpenWrt_V4.0.img of=/dev/rdisk<strong>2</strong>
  • If you are using other OS, follow the guide here (From Raspberry Pi, their are all the same except the image)
  • Eject the TF card  from your computer and insert it into Banana Pi.

Step 2: Power On your Banana Pi R1.

  • Plug in the 5V power cord to the correct port, it will power on by itself.
  • HDMI is not working on OpenWRT(only works few seconds while booting)
  • Connect the BPI-R1’s WAN to your home router/switch’s LAN (Assume DHCP is enabled )
  • Find the BPI-R1’s IP address. You may find it in the web management interface of your home router. Scan port 80 and 22 for the whole subnet other wise.
  • use root/admin to login BPI-R1
  • Mostly Done.

After that, I found only 80M(VFAT) + 150M(EXT4) was used on BPI-R1, which waste pretty much space on my 32GB TF card.

Extra Step: Expand the ext4 partition. (Inspired by SaruMaaz)

  • Download Gparted Live
  • Write Image to a Flash Drive (Assume the flash drive is disk2)
    sudo dd bs=4m if=~/Downloads/gparted-live-0.24.0-2-i586.iso of=/dev/rdisk<strong>2</strong>;sync
  • Restart OS X and hold Option key while booting,
  • Chooes ‘EFI Disk’
  • Enter your language code
  • Enter 0 and get to the GUI
  • Plug in the TF card, Find the TF card (mine is sdd)
  • Find the 150M partition, right click, change the size…
  • Apply
  • Done

How to get a certification to sign PDFs

I’m trying to get a certification to sign my PDF files these days.

My Goal:

  1. It is a certification signed by a trusted CA in Adobe Acrobat (of course it can’t be self-signed)
  2. It is cheap

What I did:

Check the current list of Adobe Approved  Trusted CA (http://helpx.adobe.com/acrobat/kb/approved-trust-list1.html)

Check those CA’s website.

Many of those CA are used inside their company/organization only, Some “Widely known CA” like DigiCert, GlobalSign, Entrust cost a lot(200-800 USD/year) for the certification, and you maybe asked for purchasing a USB device for the cert, PLUS, some of them limit the number of files you signed.

Finally I found “CERTUM (Unizeto Technologies)” in Porland, they supply a certification for a low cost(~10USD/year)  https://en.sklep.unizeto.pl/data-safety/id-certificates/certyfikat-professional-id.html

Read More

Netbeans 无法显示中文之解决方案


经过测试,使用最常用的英文字体,例如Arial, New Times Roman 都可以正常显示中文。其余字体,比如编程常用的MonoSpace,Consolas,Monaco什么的会无法显示中文。如图:


经过一番搜索,找到原因,简单地说,原因在于这些字体里面不包含中文,fallback font也没有中文.








[Apache] Rewrite subdomain as subfolder

What You Want:

—————–/123/index.php ===> http://123.yourwebsite.com/
—————–/www/index.php ===> http://www.yourwebsite.com/
—————–/blog/index.php ===> http://blog.yourwebsite.com/
—————–/email/main/index.php ===> http://email.yourwebsite.com/main/

Set dns:

A (may be AAAA) * to your server’s IP address.

This is the rewrite code you should use:

RewriteEngine On
RewriteMap lowercase int:tolower
RewriteCond %{HTTP_HOST} ^(.*)\.yourwebsite\.com$
RewriteRule ^(.*)$     /path/to/www/root/${lowercase:%1}/$1 [L]


Options -Indexes

Will not working in this case. Since Apache can not find the subfolder if you hide them. All subdomains will return a 404 error.

isset() vs empty() vs is_null()

PHP has different functions which can be used to test the value of a variable. Three useful functions for this are isset()empty() and is_null(). All these function return a boolean value. If these functions are not used in correct way they can cause unexpected results.

isset() and empty() are often viewed as functions that are opposite, however this is not always true. In this post I will explain the differences between these functions.



From PHP manual – isset():

isset — Determine if a variable is set and is not NULL

In other words, it returns true only when the variable is not null.

From PHP Manual – empty():

empty — Determine whether a variable is empty

In other words, it will return true if the variable is an empty string, false, array(), NULL, “0?, 0, and an unset variable.

From PHP Manual – is_null():

is_null — Finds whether a variable is NULL

In other words, it returns true only when the variable is null. is_null() is opposite of isset(), except for one difference that isset() can be applied to unknown variables, but is_null() only to declared variables.

The table below is an easy reference for what these functions will return for different values. The blank spaces means the function returns bool(false).
Value of variable ($var) isset($var) empty($var) is_null($var)
“” (an empty string) bool(true) bool(true)
” ” (space) bool(true)
FALSE bool(true) bool(true)
TRUE bool(true)
array() (an empty array) bool(true) bool(true)
NULL bool(true) bool(true)
“0″ (0 as a string) bool(true) bool(true)
0 (0 as an integer) bool(true) bool(true)
0.0 (0 as a float) bool(true) bool(true)
var $var; (a variable declared, but without a value) bool(true) bool(true)
NULL byte (“\ 0″) bool(true)
Copy From http://techtalk.virendrachandak.com/php-isset-vs-empty-vs-is_null/  By Virendra on January 21, 2012

Practice it CSE142 MT 06au 的一道题

Write a method named hasMidpoint that accepts three integers as parameters and returns true if one of the integers is the midpoint between the other two integers; that is, if one integer is exactly halfway between them. Your method should return false if no such midpoint relationship exists.
The integers could be passed in any order; the midpoint could be the 1st, 2nd, or 3rd. You must check all cases.
Calls such as the following should return true:
hasMidpoint(4, 6, 8)
hasMidpoint(2, 10, 6)
hasMidpoint(8, 8, 8)
hasMidpoint(25, 10, -5)
Calls such as the following should return false:
hasMidpoint(3, 1, 3)
hasMidpoint(1, 3, 1)
hasMidpoint(21, 9, 58)
hasMidpoint(2, 8, 16)

public static boolean hasMidpoint(int a,int b,int c){
    int e=a+b+c;
    if (e/3==a||e/3==b||e/3==c)
        return true;
    return false;


# name expected return your return result
1 hasMidpoint(1, 2, 3) true true pass
2 hasMidpoint(2, 10, 6) true true pass
3 hasMidpoint(0, -50, -25) true true pass
4 hasMidpoint(21, 9, 58) false false pass
5 hasMidpoint(-2, 9, 27) false false pass

public class test{
public static void main(String[] args){
public static boolean hasMidpoint(int a,int b,int c){
int e=a+b+c;
if (e/3==a||e/3==b||e/3==c)
return true;
return false;



if ((e/3==a||e/3==b||e/3==c)&&e%3==0)