WangLu's Tech Notes

2013-05-05

Notes 20130505

'tc' and 'netem' allow you to simulate some network environments
http://www.linuxfoundation.org/collaborate/workgroups/networking/netem#Delay_distribution
For example, I can delay every packet for 1s, such that in some case I can cheat in games.

Google Chrome complains about "profile cannot be opened correctly"： remove the 'web data' folder in the config dir
http://www.fourleaftechnology.com/index.php/General/google-chrome-profile-could-not-be-opened-correctly-error.html

To remove PDF password with gs
http://www.cyberciti.biz/faq/removing-password-from-pdf-on-linux/
gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=unencrypted.pdf -c .setpdfwrite -f encrypted.pdf

IE10 would ignore the `word-spacing` CSS rule if the width for the space char is 0, in a TTF font. Is it a bug of IE?

杂记 20130505

使用tc + netem可以模拟一些网络环境
http://www.linuxfoundation.org/collaborate/workgroups/networking/netem#Delay_distribution
比如我可以让每个包都延迟1秒，某些情况下玩游戏还可以作弊

Google Chrome说Profile无法正确打开：把配置目录里的'Web Data'目录干掉
http://www.fourleaftechnology.com/index.php/General/google-chrome-profile-could-not-be-opened-correctly-error.html

用gs去除PDF的密码：
http://www.cyberciti.biz/faq/removing-password-from-pdf-on-linux/
gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=unencrypted.pdf -c .setpdfwrite -f encrypted.pdf

IE10下如果TTF字体的空格宽度是0，就会无视word-spacing的css规则，不知道是不是IE的bug。

2013-04-01

Misc 20130401

To reset all shortcut definitions in evince, run
```
rm ~/.config/evince/accels
```
GCC would complain if you define a variable without actually using it. To silience it, use
```
(void)var;
```

DNS is not working in VirtualBox: Run

VBoxManage modifyvm "VM name" --natdnshostresolver1 on

Ref

A useful link talking about ravlue reference in C++11 http://thbecker.net/articles/rvalue_references/section_01.html

To clear disk cache in Linux: Run

sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches'

Ref

"screen-256color not found": Run
```
infocmp xterm-256color > screen-256color.ti
```
on a machine without this error, copy the file to the target machine and then run
```
tic screen-256color.ti
```
Ref
Just switch to fcitx from ibus. I like a theme called 'anran'. If fcitx cannot follow the cursor on Firefox, turn on preedit, as said in the official wiki.
Just played with a vim plugin called youcompleteme, for C++ autocomplete, which is quite powerful. Also I installed vundle, a vim plugin manager.

To update vimrc just after some modification, run
```
so %
```

杂记 20130401

之前evince的快捷键乱套了，使用
```
rm ~/.config/evince/accels
```
复位
定义了变量var又不用的话，gcc会报warning"unused variable"，解法是
```
(void)var;
```

VirtualBox中DNS不工作：运行

VBoxManage modifyvm "VM name" --natdnshostresolver1 on

Ref

一个讲c++11右值引用的link：http://thbecker.net/articles/rvalue_references/section_01.html

Linux清除disk cache:

sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches'

Ref

遇到错误screen-256color not found需要支持新的终端类型：找一台支持screen-256color的机器执行
```
infocmp xterm-256color > screen-256color.ti
```
把文件拷贝到目标机器后执行
```
tic screen-256color.ti
```
Ref

最近从ibus换到了fcitx，起初是由于sogou发布了，不过后来还是卸掉了。anran主题不错。fcitx在firefox中光标跟随有点问题，按官方wiki说法打开preedit后就没事了。
最近在vim里折腾youcompleteme这个补全插件，挺好用。顺便也装了vundle来管理插件，很不错
vim更新.vimrc后想直接应用，执行
```
so %
```

2013-02-26

Blogging: The 6th Year

It's been 6 years since the start of this blog, I still remember that soul-stirring accident which made me decide to start blogging.

6年博客回顾

这个blog写了6年了，还依稀记得当初促使我开始写blog的那次事故，那次真的是惊心动魄。

杂记 20120205 | Misc Notes 20120205

1. Javascript 图表库比较

Ext JS 各种模型比较折腾，画出来还不错。

flot，配合jQuery写着比较顺手，但是功能不够多，内置符号只有圆圈，加个插件发现图例中不能显示符号。logscale还有坐标的分点都要自己实现。。。

2.gnuplot编译时报错，libpng冲突

http://harvey.nu/compiling_gnuplot_on_mac_os_x_libpng_conflict.html

3.Excel中方向键不工作
按一下ScrollLock试试

http://www-cs-students.stanford.edu/~edlee/microsoft_excep_tip_1.html

4.Linux播放白噪音

http://dirk.net/2009/07/14/white-noise-generator-for-linux/

install sox

play -n synth 60:00 whitenoise

1. A few JS libraries for plotting
Ext JS, with rather complicated data models, but worthy. Produced figures look good.
flot, a smooth coding experience with jQuery, but also lack of features. E.g. by default the only available symbol is circle. There are plugins available for extra symbols, but only in legend...Also I have to specify all the ticks...

2. libpng confliction when compiling gnuplot.