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

file command

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

file command

-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

file command

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.

My Personal Notes

Nov	DEC	Jan
	14
2019	2020	2021

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