file

Additional Notes

file guesses what a file is by inspecting its contents, metadata, and magic numbers. This is often more reliable than trusting the filename extension.

Use file when investigating unknown downloads, scripts, binaries, archives, images, device files, or data produced by another program.

Syntax

file [options] file...

Parameters

• file: Path to inspect.
• options: Output, symlink, MIME, and special-file handling flags.

Common Options

• -b: Brief output. Do not print the filename before the result.
• -i: Show MIME type information.
• --mime-type: Print only the MIME type.
• --mime-encoding: Print only the MIME encoding.
• -L: Follow symbolic links.
• -s: Read block or character special files.
• -z: Try to inspect compressed files.
• -k: Keep going after the first match when possible.

Examples

file image.png

Identify a file by content.

file -i archive.tar.gz

Show MIME-style output.

file --mime-type script.sh

Print only the MIME type.

file -L symlink

Inspect the target of a symbolic link.

find . -type f -maxdepth 1 -exec file {} +

Identify multiple files in a directory.

Practical Notes

• file is a guess, not a security guarantee.
• Extensions can lie; content signatures are usually better.
• Use file -i when scripts or web servers need MIME-type information.