harvey/sys/man/1/file

.TH FILE 1
.SH NAME
file \- determine file type
.SH SYNOPSIS
.B file
[
.B -m
]
[
.I file
\&...
]
.SH DESCRIPTION
.I File
performs a series of tests on its argument
.I files
in an attempt to classify their contents by language or purpose.
If no arguments are given, the classification is performed
on standard input.
.PP
If the
.B -m
flag is given, 
.I file
outputs an
appropriate MIME
.B Content-Type
specification describing the
.B type
and
.B subtype
of each file.
.PP
The file types it looks for include
directory,
device file,
zero-filled file,
empty file,
Plan 9 executable,
PAC audio file,
.B cpio
archive,
.B tex
.B dvi
file,
archive symbol table,
archive,
.B rc
script,
.B sh
script,
PostScript,
.B troff
output file for various devices,
mail box,
GIF,
FAX,
object code,
C and Alef source,
assembler source,
compressed files,
encrypted file,
English text,
compressed image,
image,
subfont,
and
font.
.PP
If a file has no apparent format,
.I file
looks at the character set it uses to classify it according to
.SM ASCII\c
,
extended
.SM ASCII\c
, Latin
.SM ASCII\c
, or
.SM UTF
holding one or more of the following blocks of the Unicode Standard:
Extended Latin,
Greek,
Cyrillic,
Armenian,
Hebrew,
Arabic,
Devanagari,
Bengali,
Gurmukhi,
Gujarati,
Oriya,
Tamil,
Telugu,
Kannada,
Malayalam,
Thai,
Lao,
Tibetan,
Georgian,
Japanese,
Chinese,
or Korean.
.PP
If all else fails,
.I file
decides its input is
binary.
.SH SOURCE
.B /sys/src/cmd/file.c
.SH BUGS
It can make mistakes, for example classifying a file of decimal data,
.LR .01 ,
.LR .02 ,
etc. as
.IR troff (1)
input.