XScreenSaver

XScreenSaver is available on linux-based X11 systems, including major linux and BSD distributions, MacOS, iPhone, iPad and Android. It was written by Jamie Zawinski and others.

See: https://www.jwz.org/xscreensaver/
This is a very nice introduction to Writing an Xscreensaver Module using Xlib.

Sharing files between Mac and Windows

Just bought a 2TB external harddrive, but it is in NTFS format and is compatible with Windows 10 only. To use it with Mac it needs to be reformatted.

The choice is FAT32 or exFAT.

FAT32 is the traditional simple format, supported by most OS. But it cannot be applied to a disk larger than 2TB. Single file size cannot be larger than 4GB.

exFAT is an extended format of FAT32. It allows file size larger than 4GB.

Some links:

[1] How to format external hard drives for Mac and Windows
[2] How to share an external drive between a Mac and a PC
[3] Difference between exfat and fat32
[4] What is exFAT and how is it different from FAT32

SVG v.s. Canvas

How to Choose Between Canvas and SVG

Allow SSI (Server Side Includes) on bluehost

The easy way [1] is to add a .htaccess file with this line:

AddHandler server-parsed .html

That's all you need.

Another way [2] is to parse html as PHP. For this, go to cPanel >> Apache Handlers. In the "Extension(s)" box, enter html and in the "Handler" box enter application/x-httpd-php, then click "Add".

[1] https://my.bluehost.com/cgi/help/257
[2] http://www.bluehostforum.com/showthread.php?2359-I-need-help-using-server-side-includes!!

Uninstall dropbox without losing files

Say you're stop using a computer, and need to stop sharing your dropbox files on this computer, or maybe to uninstall dropbox. How can you do it safely without losing files?

You need to unlink the computer with your dropbox account. Here is an article:

3 Easy Ways to Unlink a Computer from a Dropbox Account

Move MSSQL database file path

The solution if found at: https://msdn.microsoft.com/en-us/library/ms345408.aspx


The steps are:

1) Change file path:
ALTER DATABASE [db_name] MODIFY FILE ( NAME = [db_logic_name], FILENAME = '[new path]' )
2) Stop MSSQL server.
3) Move the file.
4) Restart MSSQL server.

That's all. Now you can check status by:

SELECT name, physical_name AS CurrentLocation, state_desc
FROM sys.master_files
WHERE database_id = DB_ID(N'[db_name]');

Underscore "_" is a wild card match character in MSSQL

Besides '%', underscore '_' is also a wild card match character in MSSQL. This can lead to some very subtle bug.

Say your table name has underscore in it, e.g., there are 2 tables my_Tablename and my_WeirdTablename. You find table using 'name like %_Tablename', then you will get both tables, instead of the first one. This leads to hidden bugs that are hard to identify.

To fix this issue, use this: 'name like %[_]tablename'. The '_' char is escaped by quoting it with brackets.