USB OTG

USB is a good interface but it can be very complicated and confusing(probably only for developers?)

The USB mini-male has 2 types:

• Mini-A-male
• Mini-B-male

The USB OTG devices detect itself as a host or client depends on the ID pin(pin 4). USB Mini-A-male has internal wiring to tie the ID pin to GND, which let the host to identify itself as USB host.

While most of the USB Mini-male cable you see on the market is Mini-B-male, which leave the pin unconnected.

 

gitweb on Ubuntu/Jaunty

Make sure these GIT packages are installed:

$ aptitude install git git-core gitk gitweb

Assume the default apache web server is /var/www/ ,
gitweb is the directory I want to install gitweb:

$ cd /var/www/
$ mkdir gitweb
$ cd gitweb

copy gitweb graphics and stylesheets(git-favicon.png git-logo.png gitweb.css) to its directory, their path should correspond to what states in /etc/gitweb.conf:

$ cd /var/www/gitweb/
$ cp /usr/share/gitweb/* .

add gitweb directory to apache2 configuration by creating a “gitweb” file inside apache conf.d directory:

$ vi /etc/apache/conf.d/gitweb

Paste the following text and modify if your path is different:

Alias /gitweb /var/www/gitweb

Options Indexes FollowSymlinks ExecCGI
DirectoryIndex /cgi-bin/gitweb.cgi
AllowOverride None

Modify gitweb.conf, assuming the public GIT repositories are located in /var/www/repo/

$ vi /etc/gitweb.conf

$projectroot = “/var/www/repo/”;

# directory to use for temp files
$git_temp = “/tmp”;

# target of the home link on top of all pages
#$home_link = $my_uri || “/”;

# html text to include at home page
$home_text = “indextext.html”;

# file with project list; by default, simply scan the projectroot dir.
$projects_list = $projectroot;

# stylesheet to use
# I took off the prefix / of the following path to put these files inside gitweb directory directly
$stylesheet = “gitweb.css”;

# logo to use
$logo = “git-logo.png”;

# the ‘favicon’
$favicon = “git-favicon.png”;

restart apache2 web server:

$ sudo /etc/init.d/apache2 restart

Now you should be able to view gitweb listing all GIT projects under /var/www/repo/:
http://localhost/gitweb

 

vi copy and paste format problem

when copy and paste in vi it automatically inserts many annoying indents and tabs. To disable the auto indents and formatting, use this command before you paste

:set paste

and paste your codes. After that, set it back

:set nopaste

 

8051 Linux programmer

I just had no luck searching for this topic. Any one come across the same idea please shed me some lights.

Any cheap (universal) programmer out there can be used to compile 8051 C programs and also capable of writing the hex file into 8051 derivatives? I would also like to know what packages/compilers/similators to drive this programmer.

 

vim autocomplete

For some reason Ubuntu 8.04 didn’t install vim by default, thus no syntax.

There’s also another tips I always forgot.  vim has a very nice autocomplete feature.  For example you’ve a variable name “apple”, you can type “ap”, then press Ctrl-n or ctrl-p, it would show all the functions and variables start with “ap”.

 

How to change the default system shell back to bash

For some reason, Ubuntu changed the default system shell from bash to dash.  To what I noticed, I didn’t see any speed improvement but many scripts shows error or are not compatible.

To restore the whole system back to bash, call this command:

sudo dpkg-reconfigure dash

 

Typing Chinese in English Linux

I always prefer to install the OS in English and enable the Chinese typing tool.  The Chinese fonts on applications tool bars just don’t make much sense to me. However, enabling the Chinese tool (scim) is not done by default if I install the OS these way, so I dropped down the notes here because these steps are easily forgotten and not straight forward.

1. Go to System -> Administration -> Language Support
   Choose Chinese (Traditional and/or Simplified)
2. install packages scim-chinese, and all other dependencies
3. $ vi /etc/X11/xinit/xinput.d/scim
   change xim input to scim

   GTK_IM_MODULE=”scim”
   QT_IM_MODULE=”scim”

4. without using root, type
   $ im-switch -z <Your locale> -s scim
   your locale can be figured out by command
   $ locale | grep LANG
5. restart your X (Ctrl-Alt Del), then Ctrl-spacebar should give you a scim toolbar

P.S. After the scim toolbar is poping up, you still need to right click the toolbar to setup what input method you would like to use.  Personally, I used Changjie3 to type Chinese, it seems the closest to the Windows version of Changjie.

 

yum database clean up

Sometimes when yum is not updating, or simply not synchronized with the repository, it’s a good idea to clean up the cache database and fetch a new list from the server.

1. yum clean all
2. mv /var/cache/yum/ /tmp/
3. rm /var/lib/rpm/__db* /tmp/
4. rpm –rebuilddb

Somehow I tend to move the files to /tmp/ rather then just remove them, since the rm -rf command is the No. 1 enemy of idiocity.

 

Chinese fonts in Linux ( blur when antialias is true )

If you install your Linux box with English as the primary language, you will notice the Chinese fonts are blurred and hard to read. That is due to anti-aliasing of Chinese characters. I would NOT recommend to disable all font anti-aliasing in Font Preferences, because anti-alias is good and it makes many fonts look easier for eyes, just not Chinese characters when they are small.

The solution is so set false for Chinese fonts under a specific font size. Create a file called local.conf under /etc/fonts/ directory

vi /etc/fonts/local.conf

and copy and paste the following to the file:

<?xml version=”1.0″?><!DOCTYPE fontconfig SYSTEM “fonts.dtd”>

<fontconfig>

<!– Disable font alias for Chinese <= 18px –>

<match target=”font”>

<test qual=”any” name=”family” compare=”eq”>

<string>AR PL Mingti2L Big5</string>

<string>AR PL SungtiL Big5</string>

<string>AR PL New Sung</string>

<string>AR PL ShanHeiSun Uni</string>

<string>AR PL ZenKai Uni</string>

<string>Ming(ISO10646)</string>

<string>MingLiu</string>

<string>PMingLiu</string>

<string>Kochi Mincho</string>

<string>Baekmuk Dotum</string>

</test>

<test name=”pixelsize” compare=”less_eq”>

<double>18</double>

</test>

<edit name=”antialias”>

<bool>false</bool>

</edit>

<edit name=”hinting”>

<bool>true</bool>

</edit>

</match>

<alias>

<family>serif</family>

<prefer>

<family>Bitstream Vera Serif</family>

<family>Times New Roman</family>

<family>Times</family>

<family>AR PL New Sung</family>

<family>AR PL ShanHeiSun Uni</family>

<family>AR PL Mingti2L Big5</family>

<family>AR PL SungtiL GB</family>

<family>SimSun</family>

</prefer>

</alias>

<alias>

<family>sans-serif</family>

<prefer>

<family>Bitstream Vera Sans</family>

<family>Arial</family>

<family>Verdana</family>

<family>Helvetica</family>

<family>AR PL New Sung</family>

<family>AR PL ShanHeiSun Uni</family>

<family>AR PL kaitiM Big5</family>

<family>AR PL kaitiM GB</family>

</prefer>

</alias>

<alias>

<family>monospace</family>

<prefer>

<family>Bitstream Vera Sans Mono</family>

<family>Courier New</family>

<family>Courier</family>

<family>AR PL New Sung</family>

<family>AR PL ShanHeiSun Uni</family>

</prefer>

</alias>

</fontconfig>

 

wordpress import return admin.php

When importing wordpress to wordpress database, there are several problems I encountered.

1. Unable to create directory “uploads”
2. If your xml file is big, it forces you to download the admin.php after pressing the “Upload file and import” button.

Fixes:

1. change mode of your upload directory to writable (chmod 777 uploads)
2. edit the apache php.ini file to increase the file upload limits
   1. vi /etc/php5/apache2/php.ini
   2. change “memory_limit” from 8M to 20M, or more
   3. change “upload_max_filesize” from 5M to 20M, or more
   4. restart your apache server: /etc/init.d/apache restart

After all these modifications, you should be able to import your wordpress xml file. Good luck!