Linux file Command Summary with Examples Tutorial

Examples of the Linux file Command

Beginner

Learn to find a file's type at the Linux command line.

Video Tutorial

Videos can also be accessed from the Linux Essentials Playlist on YouTube.

Linux file Command Summary with Examples (3:54)

Video Script

The Command and Why You Need It

Our seventeenth word, or command to memorize is file from the category Files.

file allows you to display a file's type.

Common Linux file Options

-options	description
`--help`	Print help screen
`-f`, `--file`	Input a list of files

Recall from our video (tutorial) #11 we saw how the type command showed a command's type? Now we're interested in displaying a file's type, meaning is it text, or a binary like an excutable, or an image file.

Before we start, it helps to think of commands as mini programs and most follow this structure: command -option(s) argument(s).

The file command has 25 options and the argument is the file, or list of files to test.

As with many commands, a double-dash --help option is available.

The details here get complicated, so at this point, I'll just mention that the -f option allows you to input multiple filenames at once.

So why is file an important command? Well, file helps you get organized, and could help prevent you from running executables you know nothing about. And now you know how to do that.

Demonstration

Okay, the best way to embed this in your memory is by typing in your own terminal window.

Find this on your Mac using a program called Terminal. On Linux use Terminal or Konsole, and currently Microsoft is adding this functionality to Windows.

Here we go, let's start by locating the file command, with whereis file.

$ whereis file file: /usr/bin/file /usr/share/file /usr/share/man/man1/file.1.gz

There it is in /usr/bin. So let's use file on file by typing file /usr/bin/file.

$ file /usr/bin/file /usr/bin/file: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked inperpreter /lib6 4/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=51a63fc391865d8e708e15d4321c6c1a stripped

Replay that if it helps. Ok, we see it's an executable, and other technical details we shouldn't be concerned with right now.

Next, let's compare that output to the file from the previous video16.txt, using file video16.txt.

$ ls -aog total 32 drwxr-xr-x 2 4096 Oct 11 10:35 . drwxr-xr-x 5 4096 Sep 27 22:24 .. -rw------- 1 30 Sep 27 22:31 .bash_history -rw-r--r-- 1 220 Sep 27 22:24 .bash_logout -rw-r--r-- 1 3515 Sep 27 22:24 .bashrc -rw-r--r-- 1 675 Sep 27 22:24 .profile -rw-r--r-- 1 100 Oct 8 17:58 video11.txt -rw-r--r-- 1 0 Oct 9 10:36 video16.txt -rw-r--r-- 1 176 Oct 5 13:48 video5.txt $ file video16.txt video16.txt: empty

Empty. And then video11.txt?

$ file video11.txt video11.txt: ASCII text

That's an ASCII text file, very good.

And last, let's look at a configuration file like .bashrc as well.

$ file .bashrc .bashrc: ASCII text

Text as well. Excellent.

A Final Tip

Okay now you know how to use file. And you know the syntax for commands, options and arguments.

One last tip about the file command. The user manual here, (man file) while advanced, does make for interesting reading. With coffee of course.

Okay, thanks for visiting today. I hope this was a fun introduction to the file command.

Learn More About The Series

For an overview of the 100 videos, the 8 quizzes, a cheat sheet, the categories and a Q&A section, visit:

Linux file Command Summary with Examples