file command in Linux with examples

file command is used to determine the type of a file. .file type may be of human-readable(e.g. ‘ASCII text’) or MIME type(e.g. ‘text/plain; charset=us-ascii’). This command tests each argument in an attempt to categorize it.

It has three sets of tests as follows:

• filesystem test: This test is based on the result which returns from a stat system call. The program verifies that if the file is empty, or if it’s some sort of special file. This test causes the file type to be printed.
• magic test: These tests are used to check for files with data in particular fixed formats.
• language test: This test search for particular strings which can appear anywhere in the first few blocks of a file.

Syntax:

file [option] [filename]

Example: Command displays the file type

file email.py
file name.jpeg
file Invoice.pdf
file exam.ods
file videosong.mp4

Options:

• -b, –brief : This is used to display just file type in brief mode.

  Syntax:

  file -b filename
  

  Example:

  file -b email.py
  file -b input.txt
  file -b os.pdf
  

  

  Here, we can see that file type without filename.

• * option : Command displays the all files’s file type.

  file *
  

  

  The output shows all files in the home directory

• directoryname/* option : This is used to display all files filetypes in particular directory.

  Syntax:

  file directoryname/*
  

  Example:

  file work/*
  

  

  The output shows all files in a particular directory.

• [range]* option: To display the file type of files in specific range.

  Syntax:

  file [range]*
  

  Example:

  file [a-z]*
  file [a-e]*
  

  

  The output shows the range of files.

• -c option: Cause a checking printout of the parsed form of the magic file. This option is usually used in conjunction with the -m flag to debug a new magic file before installing it.

  file -c
  

  Example:

  file -c
  

  

• -f option: Read the names of the files to be examined from namefile (one per line) before the argument list. Either namefile or atleast one filename argument must be present; to test the standard input, use ‘-’ as a filename argument.

  Syntax:

  file -f -
  

  

• -F option : File and file type are separated by :. But we can change separator using -F option

  Syntax:

  file -F "-" filename
  

  Example:

  file -F - input.txt
  file -F + os.pdf
  

  

  The output shows file and file types are separated by – and +.

• -i option: To view mime type of file.

  Syntax:

  file -i filename
  

  Example:

  file -i input.txt
  file -i os.pdf
  

  

• -N option: Don’t pad filenames so that they align in the output.

  file -N *
  

  Example:

  file -N *
  

  

• -s option: For special files

  Syntax:

  file -s filename
  

  Example:

  file /dev/sda  
  file -s /dev/sda  
  file /dev/sda5  
  file -s /dev/sda5 
  

  

• filenames: Displays file types of multiple files

  Syntax:

  file filenames
  

  Example:

  file input.txt .local Desktop
  

  

• -z option: Try to look inside compressed files.

  Example:

  file -z flash.tar.gz
  

  

• –help option: Print a help message and exit.