Extension of file name

See also: Extension

In Data-processing, a extension of file name (or simply extension of file , even extension ) is a suffix given in the name of a file to identify its format. Thus, one will say that a file named truc.doc to the extension doc or .doc .

Use according to the Operating system

The suffix is separated from the name by a not (.) in MS/DOS and CP/M. It cannot count more than 3 characters.

Microsoft Windows uses the extension to carry out association between the file and the Logiciel S which can manage it. Let us note that it is possible, under Windows, to mask the extension of the files “whose type is known”. This information is indeed partially presented by the icon of the file (partially, because several extensions can correspond to the same icon).

The suffix is separated by one or more spaces in VM/CMS.

On Unix, the extension does not have a direction for the operating system, but can be used by practice, preoccupations with a clearness and applications. With the environments such as KDE and GNOME, the suffixes are also used to determine the application, the first analysis of the file during posting is based on the extension. One second analysis at the time for example of the selection of the file, is based on the utility File which inspects the contents of a file for determines the Type MIME file.

With versions 1 with 9.x of Mac OS, there did not exist extension of file. One could, of course, manually add them (especially to facilitate the exchanges of documents with the other operating systems. Since versions X (ten) of Mac OS, the documents systematically comprise extensions of files (which one can or not visualize).

Modification of the extension

One can change the extension of a file without changing the contents it, in the same manner that one can change the remainder of the name. This operation is often risky if it is not carried out with full knowledge of the facts: often the software is based on the extension to identify the type of the file and they will not be able to recognize the Format of data.

This is why Microsoft Windows mask by defect extension. This can be modified in the parameters of posting of the " options of dossiers" , and the change of extension becomes possible then. However Windows informs the user whom the file will risk " to be inutilisable" with a request for confirmation before making the change.

In Windows, it is difficult to determine the type of a file whose extension is erroneous (this can be exploited by certain users to camouflage certain files under a misleading appearance).

On the contrary, with Unix, simple the order File makes it possible to recognize the format of a file.

Examples of current extensions

  • txt: Textual file
  • pdf: pdf
  • doc: file for the Word processing Microsoft Word
  • odt: file for the Word processing OpenOffice.org Writer
  • jpeg: file image with the format JPEG
  • png: file image with the format png
  • gif: file image with the format GIF
  • mp3: audio file MP3
  • ogg: audio file OGG Vorbis
  • xls: file spreadsheet Microsoft Excel XLS
  • html: file HTML
  • wma: audio file WMA for Windows Audio Media
  • tar.gz: file files with the format Tar compressed by Gzip.

Extension of 3 characters

Under Windows, the historical Filesystem was limited for the file names to 8 characters for the name and 3 characters for the extension. This explains why the extensions originating in other systems are often truncated to 3 letters:
  • htm instead of html
  • jpg or jpe instead of jpeg
  • mpg or mpe instead of mpeg
  • tgz instead of tar.gz

See too

Related articles

External bonds and documents

  • File Extension Library
  • File-Extensions.org - The source for file extension/file formats information.
  • FilExt
  • That can serve

Simple: Spin extension

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