How to use the Linux file command | Hostvento Knowledge Base

What is the file command?

Linux is an operating system many servers use. You type commands into a window called the terminal. The file command looks inside a file and tells you what type it is. It does not trust the name. A file called photo.txt might really be a picture, and file will say so.

Think of it like checking what is inside a box instead of reading the label on the outside.

Steps

Open the terminal, or log in to your server using SSH. SSH is a safe way to control a faraway computer by typing.
Type the command with a file name:
```
file notes.txt
```
It prints the type, for example "ASCII text".
Check several files at once:
```
file index.php logo.png backup.tar.gz
```
Each file gets one line of answer.
Check every file in the current folder:
```
file *
```
The star means "everything here".
Show only the type, without the file name:
```
file -b logo.png
```
The -b option means "brief".
Show the internet media type, also called MIME type:
```
file --mime-type logo.png
```
A MIME type is a short label such as image/png that programs use to know how to open a file.
Look inside a shortcut. A symbolic link is a shortcut to another file. Use:
```
file -L shortcut-name
```
The -L option follows the shortcut and describes the real file.

Reading the answer

You may see	What it means
ASCII text	A plain text file
PNG image data	A picture in PNG format
gzip compressed data	A packed, smaller file
directory	A folder
PHP script	A PHP program file

Tip: Use file on a download you are unsure about. If a "picture" is reported as an executable program, do not open it.

Quick recap

file name tells you the real type of a file.
It checks the contents, not the file name.
Use -b for a short answer and --mime-type for the media type.
Use file * to check a whole folder.
It only reads files. It never changes them.