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Understanding the `file` Command in Linux

Linux is an operating system that thrives on its rich set of command-line utilities. One such utility is the file command, which helps users determine the type of a file. Whether it's a text file, an image, or a binary executable, the file command can provide you with information about it. This command is very useful in situations where you have files without extensions or when you are dealing with unfamiliar files. It is often employed by system administrators, developers, and Linux enthusiasts for various tasks related to file management.

Basic Syntax

The basic syntax of the file command is straightforward:

file [options] [filename]
  • options: Flags that you can use to modify the behavior of the file command.
  • filename: The name of the file you want to examine.

Common Use Cases

  1. Identifying File Type: To find out the type of a file.

    file example.txt


    example.txt: ASCII text
  2. Multiple Files: You can also check multiple files at once.

    file file1.txt file2.png


    file1.txt: ASCII text
    file2.png: PNG image data, 800 x 600, 8-bit/color RGB, non-interlaced
  3. Reading From stdin: The file command can also read from standard input.

    echo "hello world" | file -


    /dev/stdin: ASCII text

Options Table

Here is a table listing various options available for the file command along with what they do:

-bBrief output. Suppresses the filename in the output.
-cChecks the magic file for format errors.
-eSpecifies a particular test to be conducted.
-fReads file names from a provided text file.
-iOutputs MIME type strings rather than more detailed information.
-kKeeps going even after identifying the file type. Useful for files with multiple types.
-lLists the separator string for multiple file checks.
-mSpecifies an alternate magic file.
-nNo padding while displaying output.
-pPreserves access times on files.
-rRaw output for better machine readability.
-sReads blocked or special files for determination.
-zChecks for compressed files and looks at their uncompressed content.
-vDisplays the version of the file command.

Examples with Options

Using -b for Brief Output

file -b example.txt


ASCII text

Using -i for MIME Type

file -i example.png


example.png: image/png; charset=binary

Using -f to Read Filenames from a File

Create a text file named file_list.txt containing:


Then run:

file -f file_list.txt


example.txt: ASCII text
example.png: PNG image data, 800 x 600, 8-bit/color RGB, non-interlaced


The file command is a versatile utility for identifying file types in a Linux environment. By understanding its various options and use-cases, you can work more efficiently with files of all kinds. Whether you're a system administrator needing to automate tasks or a curious user wanting to understand your files better, the file command is an indispensable tool in your Linux toolkit.

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