Master Linux ‘file’ Command: Identify Types, MIME, and Links in Seconds

The Linux file utility determines a file’s type by examining its header information rather than relying on the file extension, and can also reveal the file’s encoding.

Examples

Example 1: Default usage

file book.pdf
delete.pdf: PDF document, version 1.3
file book
delete: PDF document, version 1.3

Both commands show that the presence or absence of an extension does not affect the result.

Example 2: Suppress filename

file -b book.pdf
PDF document, version 1.3

The -b (brief) option displays only the file type description.

Example 3: Show MIME type

file -i delete.pdf
delete.pdf: application/pdf; charset=binary

The -i option outputs the MIME type.

Example 4: Read filenames from a file

cat hello.txt
sunset.jpg
file -f hello.txt
sunset.jpg: JPEG image data, JFIF standard 1.01

The -f option tells file to read filenames from the specified file.

Example 5: Custom output format

file -F " === " sunset.jpg
=== JPEG image data, JFIF standard 1.01

This demonstrates a custom delimiter, though its practical use is limited.

Example 6: Inspect symbolic links

file a.jpg
a.jpg: symbolic link to `sunset.jpg'
file -L a.jpg
a.jpg: JPEG image data, JFIF standard 1.01

Without -L, file reports the link itself; with -L, it follows the link and shows the target file’s type.