Tips, Tricks and Thoughts (old)

Connect to the restricted port of a remote host via SSH tunnel

2009-11-08T19:22:00.009-05:00

There are some scenarios where you can use this technique. A remote server allows only local connections To connect to such a server, you usually have to copy your application to the remote host where the server is running. Then login to that host and run your application there. If you are developing or testing your application, you may think that it is very inconvenient when you are frequently

Windows: free more disk space by removing backup files

2009-11-07T12:02:00.001-05:00

Windows XP and Windows Vista automatically backup the old system when you install new software or updates. They create restore points for the backups. So if you want, you can return to any of the previous restore points. If you have used the system for quite a while, you would see that your disk C: is getting full because Windows keeps all those restore points from the day you bought your

Javascript/Firefox: context menu popup

2009-11-06T20:43:00.003-05:00

The context menu of Firefox behaves differently between the Windows and Linux platforms. On Linux, the context menu pops up as soon as you press down the right button of the mouse; While on Windows, it shows when you press down and release the right button. The Linux style behavior makes it difficult for an extension to capture and hack the mousedown event. We can do a little hack to emulate the

Firefox Extensions: Table Of Contents

2009-11-04T19:16:00.005-05:00

Simple Boss Key A lightweight extension that lets you use the F12 key to minimize the current browser window. Take A Break By reminding you when to take a break during surfing, it tries to help you avoid excessive web browsing and keep healthy. Boss Key and Buttons You can press the F12 key or both the mouse buttons simultaneously to hide all your browser windows. Support If you want to

Firefox Extension: Boss Key and Buttons

2009-11-04T19:08:00.007-05:00

This Firefox extension allows you to quickly minimize your browser windows by pressing the F12 key or both the left and right mouse buttons. Features - Press the F12 key to minimize your browser windows. - Press both the mouse buttons (left and right) down to minimize your browser windows. - Open and focus on a new tab with the URL you preset. - Hide the tab-bar. - Press Shift-F12 to show

Ubuntu Linux: clean cached apt archives to free up disk space

2009-11-02T18:50:00.000-05:00

If you are using Ubuntu or other Debian like Linux, you may notice each upgrade or update may eat up some of your disk space -- depending on your setup. That is because all the update packages you have downloaded are kept under the directory of /var/cache/apt/archives. From time to time, you could run command: sudo apt-get clean to remove all those downloaded packages. If you only want

Google Docs - spreadsheet - insert chart on another sheet

2009-11-01T14:23:00.001-05:00

To insert a chart for your spreadsheet data, you can highlight the wanted cells and select menu Insert|Chart.... The new chart will be put somewhere on the same sheet of the data. If you click on the chart, its menu will be shown. By selecting its menu Chart|Move to own sheet..., you can move the chart to another sheet. The chart will have its own sheet and it will fill the whole new sheet.

Javascript/Firefox: context menu popup

2009-10-29T20:38:00.002-04:00

Note: This solution has some side-effects. A better one is provided in my another post here. The context menu of Firefox behaves differently between the Windows and Linux platform. On Linux, the context menu pops up as soon as you press down the right button of the mouse; While on Windows, it shows after you press down and release the right button. We can change the Linux style behavior by

Linux: search pattern in files

2009-10-27T20:33:00.001-04:00

If you want to search a string (e.g. "TheString") or a pattern in all the files under the current directory, you know you can use: grep TheString * It will not search the files under the sub-directories. When I wanted to search all the files under each directories recursively, I don't know why but, I did this: find . -type f | xargs grep TheString or find . -type f

Firefox Extension: Take A Break

2009-10-22T20:40:00.011-04:00

Addicted to the Web? Don't compromise your health! Continuously staring at the computer can cause headaches, blurred vision, neck pain, fatigue, dry eyes. Take A Break extension tries to help you avoid or reduce these problems. It reminds you when to take a break while you are surfing the Web. Features - A little icon on the status bar will be flashing every 15 minutes to remind you a short

Google Docs - spreadsheet - set formula for a whole column/row

2009-10-17T17:51:00.001-04:00

If you want the column C to be the sum of column A and B, i.e. C1 = A1 + B1 C2 = A2 + B2 C3 = A3 + B3 ... you don't have to click on each cell of column C and add the formula repeatedly. Instead, you can: 1. Set formula for cell C1. And press the Enter button. 2. Select cell C1. You can see a little blue square at the bottom-right corner. 3. Move the mouse over the little blue

Untrusted Connection error of softmoc.com

2009-10-13T20:57:00.002-04:00

If you tried to buy stuff at https://www.softmoc.com with Firefox browser, you might encounter the error saying "This Connection is Untrusted". The Technical Details reveal that -- www.softmoc.com uses an invalid security certificate. The certificate is not trusted because the issuer

Capture screen shots with Windows Vista Snipping Tool

2009-10-10T15:20:00.002-04:00

In the old days, if you want to capture some pictures on your screen, you have to use the Print Screen button of your keyboard and save the image from the clipboard. Now, if you are using Windows Vista Home Premium edition, or other editions of Business, Ultimate or Enterprise, you can use the free Snipping Tool to capture screen shots. The Snipping Tool can be accessed from the Start button at

GTA major cities MLS listing number trend (chart)

2009-10-09T17:42:00.009-04:00

Updated daily. Only shows 3+ bedrooms detached houses in some cities with a price range. Note: Data or chart should not be used for making any kind of decisions. They are collected in a random time of a day and may not be accurate. Reference Toronto(below 350k) Brampton(below 350k) Vaughan Mississauga(below 500k) Brampton(350k-450k) Richmond Hill Mississauga(500k-1m)

GTA resale home price trend (chart)

2009-10-09T16:53:00.005-04:00

Updated twice a month.

Learn how to create a Firefox extension in 10 minutes

2009-10-05T18:01:00.011-04:00

Note: This article explains the source code of Simple Boss Key version 1.0.1, not the latest version. Is it complicated to create a Firefox extension? No. After reading this little tutorial, you will see how easy it is. Here I am using the Firefox extension of Simple Boss Key I built as the example to show you how simple a Firefox extension could be. The Simple Boss Key extension add a

Firefox extension: Simple Boss Key

2009-10-02T18:11:00.017-04:00

addCnLink('2009/10/blog-post.html'); When people come over to your desk, maybe you do not want them to see what you are browsing. This extension helps you quickly minimize your browser to the taskbar. When the key F12 is pressed, the browser will first bring the first tab to the front and then get minimized to the taskbar. If the first tab was opened with a serious page, its title would be shown

GTA new home price trend (chart)

2009-10-01T21:55:00.012-04:00

Updated monthly.

Privacy! The information your browser sends

2009-10-01T18:06:00.006-04:00

You may be suprised to see how much information your browser reveals -- + What will we discuss today? (Click me.) The trick to include a expandable drop down text in your web page. You want

MySQL Connector/J exception on timestamp

2009-09-27T15:25:00.000-04:00

If you are using MySQL JDBC driver in your Java program and the version is MySQL Connector/J 3.1, you might see this exception sometimes: Exception: Cannot convert value '0000-00-00 00:00:00' from column ... to TIMESTAMP. The exception is thrown from mysql.jdbc.ResultSet and is caused by the datetime field with an all zero value '0000-00-00 00:00:00'. Sometimes, you don't want to

A beautiful ...

2009-09-26T14:54:00.002-04:00

Even Parity -- comparison of two algorithms

2009-09-26T13:40:00.000-04:00

To set a ASCII character to even parity, we first count the number of bits with the value of 1. If the number is even, the ASCII character is already of even parity. Otherwise, we set the most significant bit of the ASCII character to 1 to make it even parity. The follow code (in Java) demonstrates that:public static byte setEvenParity(byte b){ short countOne = 0; if (0 != (b & 0x01)) ++

Print byte in hex -- comparison of two algorithms

2009-09-25T21:34:00.000-04:00

One byte contains 8 bits, or two nibbles. To represents a byte in hex, each nibble is given a hexadecimal digit in 0-9 and A-F. For example, character 'Z' whose binary value is "0101 1010" is presented as "5A".The most obvious way to print a byte in hex format is to first grab the most significant nibble and print it as the corresponding hexadecimal digit. And then do the same thing to the least

Run GUI applications as another user in Linux

2009-09-24T20:36:00.000-04:00

Supposed user1 wants to run a gnome-terminal as user2. He needs to do these:1. Login as root (or ask root to help) to setup the sudoers. Run visudo and add these:user1 ALL = (user2) NOPASSWD:ALL Note: This grants user1 to do any good or harm to user2's account. You may want to limit the commands user1 can run. 2. Create a shell script with these lines:xhost +SI:localuser:user2sudo -u user2 -