Specifically a soft Raid 1 array on ubuntu 11.10. This guide is not for raiding your boot/main drive, but rather an extra ‘data’ array.
First thing you will need is a computer/server with 2+ drives (that you don’t mind loosing the data on), the Raid mirror will end up being the smallest of the two. You may use/mix advanced format 4KB drives, but I’ll get to that later.
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Some of my favourites:
Heisenbug
It is an error, which disappears or alters when it is attempted to be identified by analogy to Heisenberg uncertainty principle in quantum physics.
Reality 101 failure
The program (or more likely feature of a program) does exactly what was asked for, but when it’s deployed it turns out that the problem was misunderstood and the program is basically useless.
Protoduction
This is a prototype that ends up in production.
Megamoth
MEGA MOnolithic meTHod. Usually, it stretches over two screens in height and often contained inside aGod Object (an object that knows or does too much). Megamoths of greater size than 2k LOC have been sighted. Beware of the megamoth!
Here is a tool to create redirection rules, primarily for rewriting pages based on a query string to a nice seo url.
Created because .htaccess files are the easiest way to break an entire site.
http://www.xnet.tk/CreateRule.php
Example:
Old Url: http://www.xnet.tk/index.php?page=123&something=else
New Url: http://www.xnet.tk/htaccess/rules/
The generated rule would be:
RewriteCond %{QUERY_STRING} ^page=123&something=else$
RewriteRule .* htaccess/rules/? [R=301,L]
It can’t handle crossing domains (yet).
Below is what I regard as a reliable method of doing gzip output compression.
One thing that normally breaks gzip compression is something printing/echoing before the ob_start (usually the result of an error, debug output, errant space somewhere etc…), this is where the ob_get_length and ob_flush come in.
The problem is that headers_sent is not a reliable way to tell if any thing has been output because it may still be in the output buffer, so if we flush it before hand problem solved.
<?php
function doPage()
{
echo 'Hello World';
}
if (ob_get_length() > 0)
@ob_flush();
if (!headers_sent() && @ob_start("ob_gzhandler"))
{
doPage();
ob_end_flush();
//Probably a good idea to exit here as more output would break it
exit;
}
else
{
doPage();
}
Updated with a more modern feel (although only for non-ie users).
Playing around with opacity which seems to work well 
Here’s a situation, You have php running on a lighttpd server via fastcgi and you want clean urls (ie. /post/123/postname).
The typical way to-do this with lighttpd is to set the error-handler to your script.
$HTTP["host"] == "my.com" {
server.document-root = "/var/www/my.com"
server.error-handler-404 = "/index.php"
}
We use an error-handler here rather than rewriting the url as with apache because there’s no way to detect if the url is actually a file (ie. your css/js files).
Problem here is that this will break query strings for anything other than the root url (query strings are what’s after the ?). ie. when accessing /post/123/postname/?confirm=true the confirm will not appear in the $_GET or $_REQUEST arrays while /?confirm=true will.
So how do we fix this? The method I’ve used is to manually parse the query string and put its values into the get and request arrays, as below.
function fix_query_string()
{
$url = "http://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];
$query = parse_url($url,PHP_URL_QUERY);
if ($query == False || empty($query))
return;
$_SERVER['QUERY_STRING'] = $query;
parse_str($query,$query);
foreach($query as $key=>$value)
{
$_GET[$key] = $_REQUEST[$key] = $value;
}
}
if (stripos($_SERVER['SERVER_SOFTWARE'], 'lighttpd') !== false)
fix_query_string();
Hope this helps!
I recently ran into a problem where a control was rendering slow enough that it caused flickering (as the screen region is cleared and then redrawn).
Looking around the ‘net I settled on rendering the control to a bitmap and then drawing the bitmap to the screen (fast operation), which is called double buffering.
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This is a clock that tells you the time by highlighting text in a block of text. In this case using a C# Console App. Not exactly original, but I thought I’d give it a try.
The progress bar counts the time until the next 5 minute mark.
Here’s a way to get a print preview dialog (or perhaps any resizeable dialog) maximised.
dlg.Show(); //Make full screen //cant use WindowState as its not a form //dlg.DesktopBounds = Screen.FromControl(dlg).WorkingArea; ((Form)dlg).WindowState = FormWindowState.Maximized; dlg.BringToFront();
Although some times it disappears behind whatever form had focus last.
Update
Looks like the dialog can be cast to a form allowing WindowState to be set.
PrintPreviewDialog dlg = new PrintPreviewDialog(); dlg.Document = doc; ((Form)dlg).WindowState = FormWindowState.Maximized; dlg.ShowDialog();
Here is some C# code to detect when a logical volume (e.g. USB Memory Stick) is inserted or removed via the WM_DEVICECHANGE message with WndProc.
However this doesn’t tell you what has been inserted/removed, you will have to poll the drives manually to find out.
If you need that you will have to register to receive events from windows which involves P/Invoking RegisterDeviceNotification (See Drive Detector at Code Project).
[...]
using System.Runtime.InteropServices;
using System.Security.Permissions;
public class MyForm : Form
{
const int WM_DEVICECHANGE = 0x0219;
const int DBT_DEVICEARRIVAL = 0x8000; // system detected a new device
const int DBT_DEVICEREMOVECOMPLETE = 0x8004; //device was removed
const int DBT_DEVNODES_CHANGED = 0x0007; //device changed
const int DBT_DEVTYP_VOLUME = 0x00000002; // logical volume
[SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
protected override void WndProc(ref Message m)
{
if (m.Msg == WM_DEVICECHANGE
&& m.WParam.ToInt32() == DBT_DEVICEARRIVAL
|| m.WParam.ToInt32() == DBT_DEVICEREMOVECOMPLETE
|| m.WParam.ToInt32() == DBT_DEVNODES_CHANGED))
{
if (m.WParam.ToInt32() != DBT_DEVNODES_CHANGED)
{
int devType = Marshal.ReadInt32(m.LParam, 4);
if (devType == DBT_DEVTYP_VOLUME)
{
//Poll drives
}
}
else
{
//Poll drives
}
}
base.WndProc(ref m);
}
}