4.2. Identifying and Working with File Types

If you are new to Linux, you may see certain file types that you do not recognize because of their unfamiliar extension. A file's extension is the last part of a file's name after the final dot (in the file sneakers.txt, "txt" is that file's extension).

Here is a brief listing of file extensions and their meanings:

4.2.1. Compressed and Archived Files

For information on working with bzip2, gzip, and tar files, refer to Section 4.3 File Compression and Archiving.

4.2.2. File Formats

4.2.3. System Files

4.2.4. Programming and Scripting Files

But file extensions are not always used, or used consistently. So what happens when a file does not have an extension, or the file does not seem to be what the extension says it is supposed to be?

That is when the file command can be helpful.

For example, you find a file called saturday without an extension. Using the file command, you can tell what type of file it is by typing:

file saturday

In the example, the command file saturday displays ASCII text, telling you it is a text file. Any file that is designated as a text file should be readable by using the cat, more, or less commands, or by using a text editor such as gedit or vi.


To learn more about file, read the man page by typing man file.

For more information on helpful commands for reading files, refer to Chapter 3 Shell Prompt Basics.