VirtualBox压缩VDI格式硬盘/调整磁盘大小

首先，看 vbox的官方文档：

http://www.virtualbox.org/manual/ch08.html#vboxmanage-modifyvdi

VBoxManage modifyhd         <uuid>|<filename>
                            [--type normal|writethrough|immutable|shareable|
                                    readonly|multiattach]
                            [--autoreset on|off]
                            [--compact]
                            [--resize <megabytes>|--resizebyte <bytes>]

VBoxManage modifyhd <uuid>|<filename>

[--type normal|writethrough|immutable|shareable|

readonly|multiattach]

[--autoreset on|off]

[--compact]

[--resize <megabytes>|--resizebyte <bytes>]

With the --compact option, can be used to compact disk images, i.e. remove blocks that only contains zeroes. This will shrink a dynamically allocated image again; it will reduce the physical size of the image without affecting the logical size of the virtual disk. Compaction works both for base images and for diff images created as part of a snapshot.For this operation to be effective, it is required that free space in the guest system first be zeroed out using a suitable software tool. For Windows guests, you can use the sdelete tool provided by Microsoft. Executesdelete -z in the guest to zero the free disk space before compressing the virtual disk image. For Linux, use the zerofree utility which supports ext2/ext3 filesystems.Please note that compacting is currently only available for VDI images. A similar effect can be achieved by zeroing out free blocks and then cloning the disk to any other dynamically allocated format. You can use this workaround until compacting is also supported for disk formats other than VDI.

关键之处正在于 sdelete 应该使用 -c -z 两个选项，而网上所以的方法都说是使用 -c 选项。

Using SDelete

SDelete is a command line utility that takes a number of options. In any given use, it allows you to delete one or more files and/or directories, or to cleanse the free space on a logical disk. SDelete accepts wild card characters as part of the directory or file specifier.

usage: sdelete [-p passes] [-s] [-q] <file or directory> ...
       sdelete [-p passes] [-z|-c] [drive letter] ...
   -a         Remove Read-Only attribute
   -c         Clean free space
   -p passes  Specifies number of overwrite passes (default is 1)
   -q         Don't print errors (Quiet)
   -s or -r   Recurse subdirectories
   -z         Zero free space (good for virtual disk optimization)

usage: sdelete [-p passes] [-s] [-q] <file or directory> ...

sdelete [-p passes] [-z|-c] [drive letter] ...

-a Remove Read-Only attribute

-c Clean free space

-p passes Specifies number of overwrite passes (default is 1)

-q Don't print errors (Quiet)

-s or -r Recurse subdirectories

-z Zero free space (good for virtual disk optimization)

所以，总结一下，正确的方法应该是这样：

在guest os 中清理系统， windows的话可以再硬盘碎片整理一下

在 guest os 中 Windows 执行 sdelete -z -c ； Linux/Debian/Ubuntu 启动到Recovery Mode执行 zerofree /dev/sdaX

VBoxManage modifyhd <uuid>|<filename> --compact

如果磁盘空间不足，使用如下命令调整（增大/加大）磁盘空间

# 调整到30G,由于默认单位是M，因此数字是 30960

$ VBoxManage modifymedium Debian.vdi --resize 30960 --compact

# 如果存在快照的话，需要删除全部快照，否则系统中看不到磁盘空间变化

# 系统中调整磁盘空间大小
$ sudo apt-get install gparted

$ sudo gparted

# 调整到30G,由于默认单位是M，因此数字是 30960

$ VBoxManage modifymedium Debian.vdi --resize 30960 --compact

# 如果存在快照的话，需要删除全部快照，否则系统中看不到磁盘空间变化

# 系统中调整磁盘空间大小

$ sudo apt-get install gparted

$ sudo gparted

参考链接

android之StrictMode介绍

Android 2.3起，新增加了一个新的类，叫StrictMode(android.os.StrictMode)。这个类可以用来帮助开发者改进他们编写的应用，并且提供了各种的策略，这些策略能随时检查报告开发者开发应用中存在的问题，比如可以监视那些本不应该在主线程中完成的工作或者其他的一些不规范和不好的代码。

StrictMode的策略和规则

　　目前，有两大类的策略可供使用

一类是关于常用的监控方面的

Disk Reads 磁盘读

Disk Writes 磁盘写

Network access 网络访问

Custom Slow Code 自定义的运行速度慢的代码分析

前面三种的意思读者应该很清楚，就是正如它们的名字所示，分别对磁盘的读和写，网络访问进行监控。而第四种的自定义慢代码分析，是仅当访问调用类的时后才触发的，可以通过这种

方法去监视运行缓慢的代码。当在主线程中调用时，这些验证规则就会起作用去检查你的代码。比如，当你的应用在下载或者解析大量的数据时，你可以触发自定义运行速度慢代码的查询分、

析，作用很大。StrictMode可以用于捕捉发生在应用程序主线程中耗时的磁盘、网络访问或函数调用，可以帮助开发者使其改进程序，使主线程处理UI和动画在磁盘读写和网络操作时变得更平

滑，避免主线程被阻塞的发生。

另一类是关于VM虚拟机等方面的策略

内存泄露的Activity对象

内存泄露的SQLite对象

内存泄露的释放的对象

其中，内存泄露的Activity对象和内存泄露的SQLite对象都比较好理解，而所谓对关闭对象的检查，主要是去监那些本该释放的对象，比如应该调用close()方法的对象

相关的违反情况可以记录在LogCat中或者存储在DropBox中(android.os.DropBox)服务中

　　如何使用：

　　放在activity的周期onCreate方法中

StrictMode.setThreadPolicy
(new StrictMode.ThreadPolicy.Builder()
.detectDiskReads()// 当发生磁盘读操作时输出
.detectDiskWrites()// 当发生磁盘写操作时输出
.detectNetwork()//访问网络时输出，这里可以替换为detectAll() 就包括了磁盘读写和网络I/O
.penaltyLog()// 以日志的方式输出
.build());

//内存溢出
StrictMode.setVmPolicy
(new StrictMode.VmPolicy.Builder()
.detectAll()
.penaltyLog()// 以日志的方式输出
.build());

StrictMode.setThreadPolicy

(new StrictMode.ThreadPolicy.Builder()

.detectDiskReads()// 当发生磁盘读操作时输出

.detectDiskWrites()// 当发生磁盘写操作时输出

.detectNetwork()//访问网络时输出，这里可以替换为detectAll() 就包括了磁盘读写和网络I/O

.penaltyLog()// 以日志的方式输出

.build());

//内存溢出

StrictMode.setVmPolicy

(new StrictMode.VmPolicy.Builder()

.detectAll()

.penaltyLog()// 以日志的方式输出

.build());

XCode 无法显示Size Inspector

XCode 升级到4.5 以后，在View的设置界面中就再也找不到Size Inspector 的踪迹了，找了很长时间，才知道原来到 4.5 的时候，引入了“Autolayout”功能来简化设计，可是，当需要手动配置某些复杂控件的时候，这个就不怎么智能了。

找到下面的方法禁止掉其自动的功能。只是所有的都要手动设置了。

在Interface Builder中选中View，然后在Attributes Builder中去掉“Use Autolayout”前面的钩，如下图：

Ubuntu 12 以及 13 清除Dash主页及电影播放器(视频)历史记录的方法

1.清除Dash主页中历史记录的方法。

系统设置－隐私－清除历史记录

也可在“应用程序”选项卡中，设置哪些应用软件不启用历史记录。

2.电影播放器用文本编辑器历史记录的清除方法。

ctrl+alt+t,打开命令行

sudo rm -v ~/.local/share/recently-used.xbel

1	sudo rm -v ~/.local/share/recently-used.xbel

Android 源代码 error: Exited sync due to fetch errors…

希望各位不要出现这个错误，出现这个错误就要折腾一会了

首先继续repo sync，若是一直提示这个错误，那么就按照下面的方法来做吧：

关于这个问题其实google是有说明的http://source.android.com/source/downloading.html，为了防止连接数过多，每个ip都需要认证。。。

第一步：从这里 the password generator 获取用户名和密码，前提是你在之前填写了你的真实姓名和邮箱

第二步：将上面的页面上以machine开头的两行复制到 ~/.netrc文件中

第三步：

repo init -u https://android.googlesource.com/a/platform/manifest --config-name

1	repo init -u https://android.googlesource.com/a/platform/manifest --config-name

多了个“/a”,并且指定 “--config-name”

参数，很多时候会用以前配置过的用户名密码，指定这个参数会重新设置用户名

然后就可以repo sync了

特别注意.netrc文件是在用户的根目录下，root用户就是/目录下，如果没有的话就自己建一个，把权限改为 777 好了

Install the Arduino IDE in Ubuntu 12.04

转自http://blog.markloiseau.com/2012/05/install-arduino-ubuntu/

Install the Arduino IDE in Ubuntu 12.04

Installing the Arduino IDE in Ubuntu only takes a few minutes. As usual, it’s a better idea to install the Arduino straight from the source, instead of relying on the version in Ubuntu’s repository. While it wasn’t hard to install the Arduino IDE, I noticed that the Arduino GUI was really slow and laggy. This is because the startup script tells Java to use Ubuntu’s GTK look and feel, which makes everything run slowly. It’s easily fixed by changing a single line in the startup script.

Update: In the Arduino 1.0.1 update, “Serial Port” is greyed out. The fix is outlined in the troubleshooting section.

Install the Arduino IDE in Ubuntu

Install gcc-avr, avr-libc and openjdk-6-jre if you don’t have it already.
Plug in the board, see where it’s connected
Download and unpack the Arduino IDEtarball
Run the IDE
Select your board model and serial port
Run a sample program
Fix the buggy interface (optional)
Troubleshooting

Everything worked out of the box, other than the interface.

Install gcc-avr and avr-libc

Gcc-avr and avr-libc give your system the tools it needs to compile c into AVR machine code:

$ sudo apt-get install gcc-avr avr-libc

1	$ sudo apt-get install gcc-avr avr-libc

If you don’t have openjdk-6-jre already, install and configure that too:

$ sudo apt-get install openjdk-6-jre
$ sudo update-alternatives --config java
(select the correct JRE if you have more than one installed)

$ sudo apt-get install openjdk-6-jre

$ sudo update-alternatives --config java

(select the correct JRE if you have more than one installed)

Once those are installed plug in your board and type $ dmesg . It will print the kernel’s ring buffer and show you what USB port your Arduino is plugged into:

$ dmesg
-- snip --
[226470.727790] usb 1-1.1: new full-speed USB device number 6 using ehci_hcd
[226470.861077] cdc_acm 1-1.1:1.0: ttyACM0: USB ACM device
[226470.861654] usbcore: registered new interface driver cdc_acm
[226470.861659] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

$ dmesg

-- snip --

[226470.727790] usb 1-1.1: new full-speed USB device number 6 using ehci_hcd

[226470.861077] cdc_acm 1-1.1:1.0: ttyACM0: USB ACM device

[226470.861654] usbcore: registered new interface driver cdc_acm

[226470.861659] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

According to dmesg, our board is plugged into ttyACM0.

Download and Run the Arduino IDE

Go to the downloads page on Arduino’s download page to get the latest Arduino IDE tarball (.tgz file) for your architecture. My laptop is 64-bit, so I chose accordingly. Once the file was finished downloading, I unzipped and ran it with the following command:

~/Downloads$ tar xzvf arduino-1.0.1-linux64.tgz
~/Downloads$ cd arduino-1.0.1
~/Downloads/arduino-1.0.1$ ./arduino
./arduino launches the Arduino IDE.

~/Downloads$ tar xzvf arduino-1.0.1-linux64.tgz

~/Downloads$ cd arduino-1.0.1

~/Downloads/arduino-1.0.1$ ./arduino

./arduino launches the Arduino IDE.

Select your board model and serial port

I’m using an Arduino MEGA 2560, so I went to Tools>Board>”Arduino Mega 2560 or Mega ADK.” At this point, I noticed that the GUI was really slow and hard to use. If you want to fix it before proceeding, exit the IDE and skip to the ”Fixing the Interface” section before proceeding.

The IDE flashed an error about how my board wasn’t accessible over the COM1 port. COM1 usually refers to a 9-pin serial port, and my laptop doesn’t even have one. I went to Tools>Serial Port and selected /dev/ttyACM0, which reflected the output I saw when I checked dmesg.

The errors went away, and I went to File>Examples>Basics>Blink and clicked upload. Sure enough, the LED started blinking. You should be ready to start writing and running Arduino programs!

Fix the Arduino IDE to make it run more smoothly in Ubuntu

Exit the Arduino IDE and go to the installation folder (the folder you unzipped from the .tgz file). Edit the “arduino” script in your favorite text editor. To make Arduino use the native Swing windowing instead of forcing the GTK look and feel, which is the cause of the bugginess, change the following line:

#comment out this line:
#java -Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel processing.app.Base
#change it to this:
java processing.app.Base

#comment out this line:

#java -Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel processing.app.Base

#change it to this:

java processing.app.Base

Just delete the -D flag and its argument. Personally, I get nostalgic about the old-school Swing look and feel, but either way, it fixed all of the lagginess issues I was experiencing.

My Arduino IDE, running in Ubuntu (using SWT instead of GTK)

Troubleshooting USB and the grayed out Serial Port

When I got the Arduino 1.0.1 update, “Serial Port” was grayed out in the tools menu. Running arduino as root ( sudo ./arduino) resolved the issue, but it’s not an acceptable solution. In my case, serial port was grayed out because my user didn’t have permission to read and write to the device.

I added my user to the dialout group with the command sudo usermod -a -G dialout mark . Usually, that would have fixed it but iserial port was still grayed out.

Changing the permissions on /dev/ttyACM0 to world readable and writeable fixed the grayed out serial port. I ran sudo chmod a+rw /dev/ttyACM0 and the serial port menu worked again.

I’ve noticed that running programs that send lots of data over USB can cause issues with the arduino programming software, making it give errors while uploading code. Holding down the reset button fixed my upload and USB errors in most cases.

Ubuntu 13.04 Android Studio "Unrecognized VM option '+UseCodeCacheFlushing'"

下载完成最新的 Android Studio 结果执行 “./android-studio/bin/studio.sh” 的时候报告

“Unrecognized VM option '+UseCodeCacheFlushing'
Could not create the Java virtual machine.”

解决方法为在 “/android-studio/bin” 目录下面找到 “studio.vmoptions”，如果你是 64未系统就打开 “studio64.vmoptions”然后删除里面的 “-XX:+UseCodeCacheFlushing”

Ubuntu12.10 Broadcom (BCM4311)无线网卡驱动问题

DELL E5400 电脑安装 Ubuntu 12.10 ，但是不能识别无线网卡，在这个时候，查看默认的驱动，默认使用的驱动存在问题。

执行

sudo apt-get install b43-fwcutter firmware-b43-installer

1	sudo apt-get install b43-fwcutter firmware-b43-installer

命令，然后重启机器，保证最后的结果为下图所示就可以了。

Ubuntu 13.04 用户安装 Flash plugin for Firefox

转自 http://imcn.me/html/y2012/11199.html

今天有童鞋在 Ubuntu QQ群中请教如果为火狐浏览器安装 flashplayer 插件问题，其实这个很简单，此教程以ubuntu 12.04 为列，其实Ubuntu 10.04 之后的版本都可以按照这样的方式安装，因为在ubuntu 软件中没有Flash plugin，那么我么需要手动添加源，去adobe官方网站就可以，使用方便，打开网站：http://get.adobe.com/cn/flashplayer/

然后如图选择“APT，适用于ubuntu 10.04 +”意思就是ubuntu10.04以上版本，再点击“立即下载”按钮。

之后弹出下面的窗口，点击“OK”就行了

软件中心会为你自动添加源地址并更新，所以你不用管，知道出现下面的的窗口，窗口被你点没有了，没关系，现在你可以在软件中心直接搜索插件了，然后点击“”install”安装就可以了，安装完毕之后别忘了重新启动火狐浏览器！

Arduino小车更换锂电池导致过载的问题分析

一直是用四节镍氢电池来作为小车的电源，某天在网上看到了一个 5V，9V，12V的多用锂电池电源，忍不住就买了个过来，本以为很轻松的换上就可以了，结果当接到12V的电源口子上面的时候，总是自动断开，进入保护模式，感觉很奇怪。

电源图片

该电源提供1.5A的极限电流，过流以后会自动切断电源。

感觉尽管小车有四个马达，但是功率不至于达到 12V*1.5A 这么恐怖的地步。

最后用我的直流电源来分析，得到惊人的发现平时的电流也就在300mA左右，但是，某个瞬间，会直接飙升到2.24A以上，这个电流实在是有些恐怖。

直流电源如下：

百思不地其解，究竟是为什么导致如此大的瞬间过载电流，幸好电源有过流保护，否则，非出事不可，锂电池可是标准的易燃易爆啊。

细想之下，发觉问题出在如下的代码上面

digitalWrite(MosfetLeftFrontWheel0, HIGH);
digitalWrite(MosfetRightFrontWheel0, HIGH);
digitalWrite(MosfetLeftTailWheel0, HIGH);
digitalWrite(MosfetRightTailWheel0, HIGH);

digitalWrite(MosfetLeftFrontWheel1, LOW);
digitalWrite(MosfetRightFrontWheel1, LOW);
digitalWrite(MosfetLeftTailWheel1, LOW);
digitalWrite(MosfetRightTailWheel1, LOW);
delay(200);

//停车
digitalWrite(MosfetLeftFrontWheel0, LOW);
digitalWrite(MosfetRightFrontWheel0, LOW);
digitalWrite(MosfetLeftTailWheel0, LOW);
digitalWrite(MosfetRightTailWheel0, LOW);

digitalWrite(MosfetLeftFrontWheel1, LOW);
digitalWrite(MosfetRightFrontWheel1, LOW);
digitalWrite(MosfetLeftTailWheel1, LOW);
digitalWrite(MosfetRightTailWheel1, LOW);

digitalWrite(MosfetLeftFrontWheel0, HIGH);

digitalWrite(MosfetRightFrontWheel0, HIGH);

digitalWrite(MosfetLeftTailWheel0, HIGH);

digitalWrite(MosfetRightTailWheel0, HIGH);

digitalWrite(MosfetLeftFrontWheel1, LOW);

digitalWrite(MosfetRightFrontWheel1, LOW);

digitalWrite(MosfetLeftTailWheel1, LOW);

digitalWrite(MosfetRightTailWheel1, LOW);

delay(200);

//停车

digitalWrite(MosfetLeftFrontWheel0, LOW);

digitalWrite(MosfetRightFrontWheel0, LOW);

digitalWrite(MosfetLeftTailWheel0, LOW);

digitalWrite(MosfetRightTailWheel0, LOW);

digitalWrite(MosfetLeftFrontWheel1, LOW);

digitalWrite(MosfetRightFrontWheel1, LOW);

digitalWrite(MosfetLeftTailWheel1, LOW);

digitalWrite(MosfetRightTailWheel1, LOW);

这段代码看似没有问题，当时也是为了方便才这样写的。

请注意 “停车”这两个字，当时为了使得小车在获得超声传感器的反馈后才会动作，因此要求小车运动一段距离以后就要停下来等待传感器。

但是如此操作导致一个严重的问题，那就是电机的启动负载问题，电机的启动电流非常大，频繁启动，尤其是多电机同步，会导致不可预测的瞬时启动功率过载，非常危险。小车可是有四个驱动电机啊！

虽然知道原因了，但是，却不好解决，原因在于，直流电机的软启动，国内的技术，唉，不提也罢，随便一个配件都是进口的，都要几张红的，关键是还没有给小车这么小的电机的专用的驱动模块，太难了，也不合适。

没办法，不过可以通过降低启动电压的方式来降低瞬时功率，代价就是电机输出功率的下降。于是把电压切换到9V，瞬时最大峰值电流一下子降到了1.2A左右。

勉强凑合。

不过最根本的解决方法，恐怕还是PWM来降低速度，电机一旦启动，就不要停下来，反而是最节能，最不容易烧毁控制芯片的。

的确是个问题。

默默的点滴

VirtualBox压缩VDI格式硬盘/调整磁盘大小

参考链接

android之StrictMode介绍

XCode 无法显示Size Inspector

Ubuntu 12 以及 13 清除Dash主页及电影播放器(视频)历史记录的方法

Android 源代码 error: Exited sync due to fetch errors…

Install the Arduino IDE in Ubuntu 12.04

Install the Arduino IDE in Ubuntu 12.04

Install the Arduino IDE in Ubuntu

Install gcc-avr and avr-libc

Download and Run the Arduino IDE

Fix the Arduino IDE to make it run more smoothly in Ubuntu

Troubleshooting USB and the grayed out Serial Port

Further Reading

Ubuntu 13.04 Android Studio "Unrecognized VM option '+UseCodeCacheFlushing'"

Ubuntu12.10 Broadcom (BCM4311)无线网卡驱动问题

Ubuntu 13.04 用户安装 Flash plugin for Firefox

Arduino小车更换锂电池导致过载的问题分析

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