clear run history in gnome panel

run "gconf-editor" and find "gnome-panel", modify "history-gnome-run".

Xen and ntpdate

ntpdate在XEN虚拟机上执行后，不能更新当前时间。
修复方法：
将下面的指令加入/etc/rc.local文件后重启机器就可以，不重启的话手动在命令行中运行此命令。

echo 1 > /proc/sys/xen/independent_wallclock
ntpdate ntp.ubuntu.com > /dev/null

nginx rewrite command spec

rewrite
syntax: rewrite regex replacement flag

default: none

context: server, location, if

This directive changes URI in accordance with the regular expression and the replacement string. Directives are carried out in order of appearance in the configuration file.

Flags make it possible to end the execution of rewrite directives.

If the replacement string begins with http:// then the client will be redirected, and any further rewrite directives are terminated.

Flags can be any of the following:

last - completes processing of rewrite directives, after which searches for corresponding URI and location
break - completes processing of rewrite directives
redirect - returns temporary redirect with code 302; it is used if the substituting line begins with http://
permanent - returns permanent redirect with code 301
Note that if a redirect is relative (has no host part), then when redirecting Nginx uses the "Host" header if the header match name of server_name directive or the first name of server_name directive, if the header does not match or is absent. If no server_name is set, then the local hostname is used. If you want Nginx to always use the "Host" header, you can use a wildcard "*" server_name (but see the restrictions on doing so). Example:

rewrite ^(/download/.*)/media/(.*)\..*$ $1/mp3/$2.mp3 last;
rewrite ^(/download/.*)/audio/(.*)\..*$ $1/mp3/$2.ra last;
return 403;

But if we place these directives in location /download/, then it is necessary to replace flag "last" by "break", otherwise Nginx will hit the 10 cycle limit and return error 500:

location /download/ {
rewrite ^(/download/.*)/media/(.*)\..*$ $1/mp3/$2.mp3 break;
rewrite ^(/download/.*)/audio/(.*)\..*$ $1/mp3/$2.ra break;
return 403;
}

If in the line of replacement arguments are indicated, then the rest of the request arguments are appended to them. To avoid having them appended, place a question mark as the last character:

rewrite ^/users/(.*)$ /show?user=$1? last;

Note: for curly braces( { and } ), as they are used both in regexes and for block control, to avoid conflicts, regexes with curly braces are to be enclosed with double quotes (or single quotes). For example, to rewrite URLs like:

/photos/123456
to:

/path/to/photos/12/1234/123456.png
use the following (note the quotes enclosing the regex):

rewrite "/photos/([0-9] {2})([0-9] {2})([0-9] {2})" /path/to/photos/$1/$1$2/$1$2$3.png;

If you specify a ? at the end of a rewrite then Nginx will drop the original $args (arguments). When using $request_uri or $uri&$args you should specify the ? at the end of the rewrite to avoid Nginx doubling the query string.

Example using $request_uri in a rewrite from www.example.com to example.com

server {
server_name www.example.com;
rewrite ^ http://example.com$request_uri? permanent;
}

Also rewrite operates only on path, not parameters. To rewrite a URL with parameters to another URL, use this instead:

if ($args ^~ post=100){
rewrite ^ http://example.com/new-address.html? permanent;
}

Note that the $args variable is not decoded, unlike URIs during location matching.

phpunit error in ubuntu 11.04

Got below warning when run phpunit in ubuntu 11.04:

PHP Warning: require_once(PHP/CodeCoverage/Filter.php): failed to open stream: No such file or directory in /usr/bin/phpunit on line 38
PHP Stack trace:
PHP 1. {main}() /usr/bin/phpunit:0
PHP Fatal error: require_once(): Failed opening required 'PHP/CodeCoverage/Filter.php' (include_path='.:/usr/share/php:/usr/share/pear') in /usr/bin/phpunit on line 38
PHP Stack trace:
PHP 1. {main}() /usr/bin/phpunit:0

repair commands:

sudo apt-get remove phpunit
sudo pear channel-discover pear.phpunit.de
sudo pear channel-discover pear.symfony-project.com
sudo pear channel-discover components.ez.no
sudo pear update-channels
sudo pear upgrade-all
sudo pear install --alldeps phpunit/PHPUnit
sudo apt-get install phpunit

修复 ubuntu 11.04 亮度调节组合键功能

安装N卡驱动之后，Thinkpad的Fn+Home调节亮度的组合键失效。
修改/etc/X11/xorg.conf 文件，加入Option那一行，重启生效。

Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "NVS 3100M"
Option "RegistryDwords" "EnableBrightnessControl=1"
EndSection

IDE aptana menu problem in ubuntu 11.04

#!/bin/bash
export UBUNTU_MENUPROXY=0
/path/to/AptanaStudio3

Modifying the Query String In mod_rewrite of Apache2

RewriteRule backreferences: These are backreferences of the form $N (0 <= N <= 9), which provide access to the grouped parts (in parentheses) of the pattern, from the RewriteRule which is subject to the current set of RewriteCond conditions..
RewriteCond backreferences: These are backreferences of the form %N (1 <= N <= 9), which provide access to the grouped parts (again, in parentheses) of the pattern, from the last matched RewriteCond in the current set of conditions.

By default, the query string is passed through unchanged. You can, however, create URLs in the substitution string containing a query string part. Simply use a question mark inside the substitution string to indicate that the following text should be re-injected into the query string. When you want to erase an existing query string, end the substitution string with just a question mark. To combine new and old query strings, use the [QSA] flag.

# rewrite without old query string
RewriteCond %{QUERY_STRING} ^page_id=(.*)$
RewriteRule ^index.php$ /index/%1.php? [R=301,L]

# rewrite with new query string
RewriteCond %{QUERY_STRING} ^page_id=(.*)$
RewriteRule ^index.php$ /index/%1.php\?test=1 [R=301,L]

# rewrite with combined old query string
RewriteCond %{QUERY_STRING} ^page_id=(.*)$
RewriteRule ^index.php$ /index/%1.php\?test=1 [QSA,R=301,L]

globalEval function of jQuery changed in version 1.6

globalEval function of jquery before version 1.6, such as 1.5.2 and 1.2.6, source code:

// Evalulates a script in a global context
globalEval: function( data ) {
if ( data && rnotwhite.test(data) ) {
// Inspired by code by Andrea Giammarchi
// http://webreflection.blogspot.com/2007/08/global-scope-evaluation-and-dom.html
var head = document.head || document.getElementsByTagName( "head" )[0] || document.documentElement,
script = document.createElement( "script" );

if ( jQuery.support.scriptEval() ) {
script.appendChild( document.createTextNode( data ) );
} else {
script.text = data;
}

// Use insertBefore instead of appendChild to circumvent an IE6 bug.
// This arises when a base node is used (#2709).
head.insertBefore( script, head.firstChild );
head.removeChild( script );
}
},

globalEval function of jquery 1.6 source code:

// Evaluates a script in a global context
// Workarounds based on findings by Jim Driscoll
// http://weblogs.java.net/blog/driscoll/archive/2009/09/08/eval-javascript-global-context
globalEval: function( data ) {
if ( data && rnotwhite.test( data ) ) {
// We use execScript on Internet Explorer
// We use an anonymous function so that context is window
// rather than jQuery in Firefox
( window.execScript || function( data ) {
window[ "eval" ].call( window, data );
} )( data );
}
},

rails 3.0.7 在ubuntu 11.04中安装问题

$> sudo gem install rails

This is the problematic part:

File not found: lib
ERROR: While generating documentation for rails-3.0.7
... MESSAGE: exit
...

这个问题是因为Rails新版本使用了最新的Rdoc/ri版本，而系统中原来的版本有些功能不是兼容的，因此报错。
卸载已经安装的rails3，先安装rdoc-data成功后再安装rails3。

$> sudo gem uninstall rails --version 3.0.7
$> sudo gem install rdoc-data
$> sudo rdoc-data --install
$> sudo gem install rails

安装成功信息：
Successfully installed rails-3.0.7
1 gem installed
Installing ri documentation for rails-3.0.7...
Installing RDoc documentation for rails-3.0.7...