Identifying and Working with File Types

If you are new to Linux, you may see files with extensions you do not recognize. 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:

Compressed and Archived Files

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

File Formats

System Files

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 instance, 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

It will display ASCII text, telling you it is a text file. Any file that is designated a text file should be readable using the cat, more, or less commands.


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

For more information on helpful commands for reading files, see Chapter 11.