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Linux in a Nutshell, Fourth Edition by Aaron Weber, Stephen Figgins, Ellen Siever

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Name

file

Synopsis

                  file [options] files
               

Classify the named files according to the type of data they contain. file checks the magic file (usually /usr/share/magic) to identify some file types.

Options

-b

Brief mode; do not prepend filenames to output lines.

-c

Check the format of the magic file (files argument is invalid with -c). Usually used with -m.

-f file

Read the names of files to be checked from file.

-L

Follow symbolic links. By default, symbolic links are not followed.

-m file

Search for file types in file instead of /usr/share/magic.

-n

Flush standard output after checking a file.

-s

Check files that are block or character special files in addition to checking ordinary files.

-v

Print the version.

-z

Attempt checking of compressed files.

Many file types are understood. Output lists each filename, followed by a brief classification such as:

ascii text
c program text
c-shell commands
data
empty
iAPX 386 executable
directory
[nt]roff, tbl, or eqn input text
shell commands
symbolic link to ../usr/etc/arp

Example

List all files that are deemed to be troff/nroff input:

                  file * | grep roff

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