The simple answer is that Unix does not use extensions for program associations. Everything in Unix is a file, whether it is a device, a data file, or a program. In Unix it is controlled by permissions, primarily the execute permission.
Also, by checking the first block of a file for its content we can determine what program to use with a file (usually in a graphical mode).
No, folders usually do not have file extensions, but they could have if you like. Usually only files have extensions, to indicate the contents of the file.
only Dos-based operating systems use dot-three file extensions
Every computer file has some extentions like .html, .txt, .xls etc For example when you create a text file using Notepad, say anil.txt Here anil is the file name and .txt is the extension.
Because for the text editor (and the operating system) there is no such thing as 'C file' only 'file', and files can have any names and extensions.
There are no set file extensions for an ASCII text file, however one that is commonly used is .txt
Windows hides file extensions in File Explorer by default for known file types to simplify the user experience and reduce clutter. This setting can be adjusted in the Folder Options menu, where users can choose to show file extensions for all files. The option is typically turned on for security reasons, as displaying extensions can help users identify potentially harmful files. To view file extensions, users can enable the "File name extensions" checkbox in the "View" tab of the Ribbon in File Explorer.
File extensions are still necessary on Windows. They are no longer limited to three characters on FAT32 and NTFS file systems, though most system files were named with three character extensions in case someone wanted to use FAT16, and many are still named this way for backwards-compatibility purposes.
Rules for file extensions are based mainly on the underlying operating system and/or file system. Generally speaking, file extensions are just a part of the file name, and can be set to whatever you like.
What do file extensions like avi, dv, dvd, mpeg mean?
For windows, you might use .cmd, .bat as common file extensions. Unix doesn't use file extensions as associations, so no file extension needs to be used in the Unix environment. A shell script in Unix is simply a text file with any name that is readable and executable. However, file extensions are typically used in Unix as a documentation aid that states that the file is a shell script. Common extensions are .sh, .csh, .ksh, .tcsh, .zsh, etc.
File extensions can range from 1 letter to 7 letters. For example ".A" used with Unix library or ".TORRENT" which stores metadata used for BitTorrent, and even double file extensions such as ".TAR.GZ" formed when a ".TAR" is compressed with a ".gzip".
File extensions tell the computer what kind of program was used to create it, and are usually three letters. Common file extensions are .txt .doc .wps