$ file Map Map: RIFF (little-endian) data
The file program indicated that the file I downloaded, which was a campus
map, was in the
Resource Interchange File Format (RIFF), a file
container format that was introduced by Microsoft and IBM
in 1991; it was the default format for
Microsoft
Windows 3.1 multimedia files. The format is based on the
Interchange File Format (IFF) introduced by
Electronic Arts for the
Commodore Amiga Amiga in 1985. However, whereas
multi-byte
integers are stored in
big-endian format, which is a format native to the 68k processor series
used in Amiga and Apple Macintosh computers, RIFF files use the
little-endian
format, which is why the file utility reports "RIFF
(little-endian) data".
How does the file utility recognize it as a RIFF file? When the file program examines the first 4 bytes of the file, it sees the hexadecimal values 46 46 49 52, which identifies the file as a RIFF file - see The Dr. Agon WAV File Format Page for a full discussion of the format.
I can see that by using the od command.
$ od -t x -N 4 Map 0000000 46464952 0000004 $
The -t x option instructs the od utility to display its
output in hexadecimal and the -N 4 option tells it to display
only the first 4 bytes of the file. Note: if you choose to display the
data as hexadecimal shorts, instead, you will see the first 4 bytes listed as
49 52 46 46, but if you choose to display as hexadecimal ints, as above, you
will see them displayed as 46464952.
-H, -X Output hexadecimal ints. Equivalent to -t x4.
-h, -x Output hexadecimal shorts. Equivalent to -t x2.I.e.:
$ od -H -N 4 Map 0000000 46464952 0000004 GSSLA15122293:convert-riff jmcamer1$ od -h -N 4 Map 0000000 4952 4646 0000004
Since the RIFF file format is a container file format, I looked at the
first 16 bytes to determine the type of image stored in the file. I used
the -t a and -t c options for displaying the data
this time to see the ASCII representation of the data in the file this time.
-t type Specify the output format. type is a string containing one
or more of the following kinds of type specifiers:
a Named characters (ASCII). Control characters are
displayed using the following names:
000 NUL 001 SOH 002 STX 003 ETX 004 EOT 005 ENQ
006 ACK 007 BEL 008 BS 009 HT 00a NL 00b VT
00c FF 00d CR 00e SO 00f SI 010 DLE 011 DC1
012 DC2 013 DC3 014 DC4 015 NAK 016 SYN 017 ETB
018 CAN 019 EM 01a SUB 01b ESC 01c FS 01d GS
01e RS 01f US 020 SP 0ff DEL
c Characters in the default character set. Non-print-
ing characters are represented as 3-digit octal char-
acter codes, except the following characters, which
are represented as C escapes:
NUL \0
alert \a
backspace \b
newline \n
carriage-return \r
tab \t
vertical tab \v
Multi-byte characters are displayed in the area cor-
responding to the first byte of the character. The
remaining bytes are shown as `**'.That showed me that the file was a RIFF file with an image within it of WEBPVP8, which is a format used by Google.
$ od -t c -N 16 Map 0000000 R I F F 320 p 002 \0 W E B P V P 8 0000020 GSSLA15122293:convert-riff jmcamer1$ od -t a -N 16 Map 0000000 R I F F ? p stx nul W E B P V P 8 sp 0000020
Note the "R" in "RIFF" is represented by the hexadecimal value 52 in the ASCII encoding standard wile "I" is represented by hex 49 and "F" by 46.
I was able to view the file by opening it in the Google Chrome browser on the system by clicking on File from its menu bar, selecting Open File and then selecting the Map file.
References: