illumos: 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