Beginners Guide for File Command on Linux

Linux TLDR
Last Updated:
Reading time: 2 minutes

The file command in Linux is used to determine the MIME encoding (e.g. “image/jpeg; charset=binary”) or file type (e.g. “ASCII text”) for the target file.

Tutorial Details

DescriptionDetermine file type
Difficulty LevelLow
Root or Sudo PrivilegesYes (for one command)
OS CompatibilityUbuntu, Manjaro, Fedora, etc.
Internet RequiredNo

The result (stdout data) comes from the three sets of tests as follows:

  • The filesystem test is used to determine the type of the file or whether the file is empty using the stat command result.
  • Than magic test is performed to check the file for data in particular fixed formats.
  • Lastly, the language test is used to search for particular strings that can appear anywhere in the first few blocks of a file.

Syntax of the File Command

The file command requires two arguments: one is the option, and the other is the filename.


Find the Type of the File

The following command will return the property or description of the referenced file (it will also work for files without extensions).

$ file file.txt


Checking the type of file

Printing only the File Type

From the above command, you can remove “file.txt:” from the output by just printing the “ASCII text” in brief mode using the “-b” flag.

$ file -b file.txt 


Removing the filename from file command output

Printing the Type of Multiple Files

You can pass multiple files as an argument to the file command to print their properties.

$ file file.txt 


Checking the property of multiple files

Listing the Files Type in the Current Working Directory

Replace “file.txt” with a “*” wildcard to print the property for all files and directories in the current working directory.

$ file *


Checking the properties of all files in the current working directory

Listing the Files Type for the Target Directory

Following the previous command, you can specify the directory path and use the “*” wildcard to list all the file properties in the target directory.

$ file Documents/*


Checking the file property in a different location

Listing the Files Type for Specific Range

Specify the range of files within the square bracket “[RANGE]” to find the file property.

$ file [a-z]*


Checking the property for the range of files

Align the Output

As you can see above, the padding makes the command unaligned, which can be aligned using the “-N” flag.

$ file -N [a-z]*


Removing padding from output

Look Inside the Compressed File

The following command will look into the compressed “.zip” or “.tar.xz” files and determine the file property inside.

$ file -z 
$ file -z file.tar.xz 


Determine the file property inside the compressed file

Reading the Special Files

The “-s” flag allows you to read special files like “/dev/sda” or “/dev/null” files, as shown.

$ sudo file -s /dev/sda
$ file -s /dev/null


Checking the properties of special files

Reading the File MIME Encoding

The “-i” flag can be used to determine the MIME encoding for the target file.

$ file -i file.tar.xz 
$ file -i file.txt
$ file -i photo.jpg 


Checking the MIME encoding of the referenced file

That was the end of the final example.

Bye bye! We’ll talk again in the next article.

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