2 Find file types by using a modified "magic" file
4 Based on file v3.22 by Ian F. Darwin (see libfile/LEGAL.NOTICE and
5 libfile/README.dist - File v3.22 can be found at many archive sites)
7 For each entry in the magic file, the "message" for the initial offset MUST
8 be 4 characters for the CREATOR and 4 characters for the TYPE - white space is
9 optional between them. Any other characters on this line are ignored.
10 Continuation lines (starting with a '>') are also ignored i.e. only the initial
11 offset lines are used.
13 e.g magic entry for a GIF file:
15 # off type test message
18 0 string GIF8 8BIM GIFf
19 >4 string 7a \b, version 8%s,
20 >4 string 9a \b, version 8%s,
23 #>10 byte &0x80 color mapped,
24 #>10 byte&0x07 =0x00 2 colors
25 #>10 byte&0x07 =0x01 4 colors
26 #>10 byte&0x07 =0x02 8 colors
27 #>10 byte&0x07 =0x03 16 colors
28 #>10 byte&0x07 =0x04 32 colors
29 #>10 byte&0x07 =0x05 64 colors
30 #>10 byte&0x07 =0x06 128 colors
31 #>10 byte&0x07 =0x07 256 colors
33 Just the "8BIM" "GIFf" will be used whatever the type of GIF file it is.
34 The continuation lines are used by the "file" command, but ignored by
35 mkhybrid. They could be left out completely.
37 The complete format of the magic file is given in the magic man page (magic.5).
39 See the file "magic" for other examples
41 Use with the -magic magic_file option, where magic_file is a file
44 The magic file can be used with the mapping file (option -map) - the order
45 these options appear on the command line is important. mkhybrid will try to
46 detect if the file is one of the Unix/Mac files (e.g. a CAP or Netatalk
47 file) first. If that fails, it will then use the magic and/or mapping
50 mkhybrid -o output.raw -map mapping -magic magic src_dir
52 The above will check filename extensions first, if that fails to set the
53 CREATOR/TYPE, the magic file will be used. To check the magic file
54 before the filename extensions, use:
56 mkhybrid -o output.raw -magic magic -map mapping src_dir
59 Using just a magic file - filename extensions will not be checked e.g:
61 mkhybrid -o output.raw -magic magic src_dir
63 For the magic method to work, each file must be opened and read twice
64 (once to find it's CREATOR/TYPE, and a second time to actually copy the
65 file to the CD image). Therefore the -magic option may significantly
66 increase processing time.
68 If a file's CREATOR/TYPE is not set via the magic and mapping matches,
69 then the file is given the default CREATOR/TYPE.