Tribblix: manual page: file.1

FILE(1) User Commands FILE(1)

NAME

file - determine file type

SYNOPSIS

/usr/bin/file [-bdh] [-m mfile] [-M Mfile] [-f ffile] file...

/usr/bin/file [-bdh] [-m mfile] [-M Mfile] -f ffile

/usr/bin/file -i [-bh] [-f ffile] file...

/usr/bin/file -i [-bh] -f ffile

/usr/bin/file -c [-d] [-m mfile] [-M Mfile]

/usr/xpg4/bin/file [-bdh] [-m mfile] [-M Mfile] [-f ffile] file...

/usr/xpg4/bin/file [-bdh] [-m mfile] [-M Mfile] -f ffile

/usr/xpg4/bin/file -i [-bh] [-f ffile] file...

/usr/xpg4/bin/file -i [-bh] -f ffile

/usr/xpg4/bin/file -c [-d] [-m mfile] [-M Mfile]

DESCRIPTION

The file utility performs a series of tests on each file supplied by
file and, optionally, on each file listed in ffile in an attempt to
classify it. If the file is not a regular file, its file type is
identified. The file types directory, FIFO, block special, and
character special are identified as such. If the file is a regular
file and the file is zero-length, it is identified as an empty file.

If file appears to be a text file, file examines the first 512 bytes
and tries to determine its programming language. If file is a
symbolic link, by default the link is followed and file tests the
file to which the symbolic link refers.

If file is a relocatable object, executable, or shared object, file
prints out information about the file's execution requirements. This
information includes the machine class, byte-ordering, static/dynamic
linkage, and any software or hardware capability requirements. If
file is a runtime linking configuration file, file prints information
about the target platform, including the machine class and byte-
ordering.

By default, file will try to use the localized magic file
/usr/lib/locale/locale/LC_MESSAGES/magic, if it exists, to identify
files that have a magic number. For example, in the Japanese locale,
file will try to use /usr/lib/locale/ja/LC_MESSAGES/magic. If a
localized magic file does not exist, file will utilize /etc/magic. A
magic number is a numeric or string constant that indicates the file
type. See magic(5) for an explanation of the format of /etc/magic.

If file does not exist, cannot be read, or its file status could not
be determined, it is not considered an error that affects the exit
status. The output will indicate that the file was processed, but
that its type could not be determined.

OPTIONS

The following options are supported:

-b
Be brief, do not print leading filename.

-c
Checks the magic file for format errors. For reasons of
efficiency, this validation is normally not carried out.

-d
Applies any position-sensitive and context-sensitive
default system tests to the file.

-f ffile
ffile contains a list of the files to be examined.

-h
When a symbolic link is encountered, this option
identifies the file as a symbolic link. If -h is not
specified and file is a symbolic link that refers to a
non-existent file, the file utility identifies the file
as a symbolic link, as if -h had been specified.

-i
If a file is a regular file, this option does not attempt
to classify the type of file further, but identifies the
file as a "regular file".

-m mfile

/usr/bin/file
Uses mfile as an alternate magic
file, instead of /etc/magic.

/usr/xpg4/bin/file
Specifies the name of a file
containing position-sensitive tests
that are applied to a file in order
to classify it (see magic(5)). If
the -m option is specified without
specifying the -d option or the -M
option, position-sensitive default
system tests are applied after the
position-sensitive tests specified
by the -m option.

-M Mfile
Specifies the name of a file containing position-
sensitive tests that are applied to a file in order to
classify it (see magic(5)). No position-sensitive default
system tests nor context-sensitive default system tests
are applied unless the -d option is also specified.

If the -M option is specified with the -d option, the -m option, or
both, or if the -m option is specified with the -d option, the
concatenation of the position-sensitive tests specified by these
options is applied in the order specified by the appearance of these
options.

OPERANDS

The following operands are supported:

file
A path name of a file to be tested.

USAGE

See largefile(7) for the description of the behavior of file when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).

EXAMPLES

Example 1: Determining if an Argument is a Binary Executable Files

The following example determine if an argument is a binary executable
file:

file "$1" | grep -Fq executable &&
printf "%s is executable.\n" "$1"

ENVIRONMENT VARIABLES

See environ(7) for descriptions of the following environment
variables that affect the execution of file: LANG, LC_ALL, LC_CTYPE,
LC_MESSAGES, and NLSPATH.

EXIT STATUS

The following exit values are returned:

0
Successful completion.

>0
An error occurred.

FILES

/etc/magic
file's magic number file

ATTRIBUTES