Linux Pocket Guide, 2nd Edition

Name

file — stdin  stdout  - file  -- opt  --help  --version

Synopsis

file [options] files

The file command reports the type of a file:

$ file /etc/hosts /usr/bin/who letter.doc
/etc/hosts:    ASCII text
/usr/bin/who:  ELF 32-bit LSB executable, Intel 80386 ...
letter.doc:    Microsoft Office Document

Unlike some other operating systems, Linux does not keep track of file types, so the output is an educated guess based on the file content and other factors.

Useful options

-b	Omit filenames (left column of output).
-i	Print MIME types for the file, such as “text/plain” or “audio/mpeg”, instead of the usual output.
-f name_file	Read filenames, one per line, from the given name_file, and report their types. Afterward, process filenames on the command line as usual.
-L	Follow symbolic links, reporting the type of the destination file instead of the link.
-z	If a file is compressed (see File Compression and Packaging), examine the uncompressed contents to decide the file type, instead of reporting “compressed data.”