what is the purpose of an extention in a filename?

Question

what is the purpose of an extention in a filename?

Answer 1

To know which software program to open or specific action to take. Eg. the extension .doc will open MS Word; .xls MS Excel

Answer 2

In Microsoft, it was intended to help processing. Again, they screwed the pooch!



In Mac, Extensions really do speed up the processing!!!



In Linux, they are not obvious, and, the filesystem opens by decoding the initial matrix to determine, on the fly, the proper ocntext of the file at 50X faster speeds than the Microsoft PC.



Then, there are occasions where the OSes are confused, and a window opens that lets the user choose the correct application.



OR, the user can aply an asociation in a window, in the MAC and in Linux, BSD...



In Microsoft, you are given a window, and then it crashes. Sometimes, the second time you open a similar application extension, it just picks the most in-apppropriate application to use, and it forces you to obey the System Lord and bow down to the Evil Empire... great if you have lots of time.



Most of us have moved on, from Mcirosft, to Mac, or Linux at http://pclinuxos.com



That includes Microsoft, who switched years ago, for Microsoft.com, hotmail.com, MSN.com, and the entire Redmond Campus, on 45,000 Linux computers...

Answer 3

Here's your answer:

http://en.wikipedia.org/wiki/Filename_extension



Tip: Learn to use Google and Yahoo Search to find what you are looking for.

I found the above site using the search phrase: what is a filename extension.



http://www.google.com/

or

http://uk.yahoo.com/



Good Luck

Answer 4

Identification.

Answer 5

Linuxiac covered most of this.



File extensions are to help both user and machine to identify and classify files. Depending on your OS they are used differently.



In Linux you any file can be an executable if you change the permissions to allow execution. Thus you can name your executables just about anything you want. The common conventions are to name executables .bin or have no extension at all. Shell scripts often have a .sh extension to denote it is a shell script. Libs have a .lib extension and shared objects usuallly have a .so extension.



In windoze for a file to be an executable it must have certain extensions. Most typically it will have a .exe extension. .dll is supposed to be for purely dynamic link libs but some executables carry this extension. .com .bat .vbx and so on are some other extensions that make a file executable. Virus writers have in the past used obscure executable extensions to get past virus scanners and filters. Microsoft loves to hide the extension from you and this combination is often dangerous to the user. One of the many security problems with Microsoft operating systems is this tendancy to hide the extension from you. It has in the past often caused users to unwittingly execute malicious programs thinking they were something safe. This can be fixed on a global scale by changing your preferences. The exact location of such varies with windoze versions.



From a command line extensions are an invaluable way of organizing your hard drive. For example I am able in seconds to do things that would take me minutes to as much as an hour using a command line and file extensions rather than have to individually click on files or to first sort by extension then click on ranges of files. Without good extensions this becomes insanely difficult when you have thousands of files. This is a major shortcoming of windoze operating systems. For example when I write a book or short story I create a file name that includes the revision as well as the name of the story and the type of file. Whether it be charactor information, actual story text, timelines and so on. This allows me to easily act upon revisions. If I want to throw away a whole series of edits I can in seconds wipe them from the dir. By using custom extensions in Linux I am able to have thousands of files in a single subdir which can be easily accessed and operated on by classifications using the extensions. Windoze almost forces you to use a .txt extension for all text files. This is extremely annoying and makes a major mess requiring very complex dir structures to be able to work with large numbers of text files efficiently. It also hinders progrmatically using files you've edited in a text editor or word processor.



Many pieces of software are written by lazy programmers. Especially in windows where the extension if often the only check done to see what kind of file a program is attempting to open. In Linux most software will open the headers and read what type of file. So your image viewer will know that you have an image even if it does not end with an image extension. It will also not attempt to open a zip file that has been accidentally or intentionally given a .jpg extension.



You can in most browsers set up automatic operations when you attempt to download files with certain extensions or mime types. A mime type is the web equivalent of an extension in that it classifies what type of file is being transfered. It does more than that but for this purpose that's as deep as we need to go. So you can configure your browser to send certain files automatically to the disk, some like a PDF to give you a choice of opening with a certain piece of software or downloading or to send that file directly to another app such as a word processor to be opened right then.



So in short it's to help both user and machine understand what kind of file you are dealing with and what you can do with that file.

Answer 6

Isn't that obvious? Duh.