1# @(#)README 1.1 98/06/16 joerg 2 3Find file types by using a modified "magic" file 4 5Based on file v3.22 by Ian F. Darwin (see libfile/LEGAL.NOTICE and 6libfile/README.dist - File v3.22 can be found at many archive sites) 7 8For each entry in the magic file, the "message" for the initial offset MUST 9be 4 characters for the CREATOR and 4 characters for the TYPE - white space is 10optional between them. Any other characters on this line are ignored. 11Continuation lines (starting with a '>') are also ignored i.e. only the initial 12offset lines are used. 13 14e.g magic entry for a GIF file: 15 16# off type test message 17# 18# GIF image 190 string GIF8 8BIM GIFf 20>4 string 7a \b, version 8%s, 21>4 string 9a \b, version 8%s, 22>6 leshort >0 %hd x 23>8 leshort >0 %hd, 24#>10 byte &0x80 color mapped, 25#>10 byte&0x07 =0x00 2 colors 26#>10 byte&0x07 =0x01 4 colors 27#>10 byte&0x07 =0x02 8 colors 28#>10 byte&0x07 =0x03 16 colors 29#>10 byte&0x07 =0x04 32 colors 30#>10 byte&0x07 =0x05 64 colors 31#>10 byte&0x07 =0x06 128 colors 32#>10 byte&0x07 =0x07 256 colors 33 34Just the "8BIM" "GIFf" will be used whatever the type of GIF file it is. 35The continuation lines are used by the "file" command, but ignored by 36mkhybrid. They could be left out completely. 37 38The complete format of the magic file is given in the magic man page (magic.5). 39 40See the file "magic" for other examples 41 42Use with the -magic magic_file option, where magic_file is a file 43described above. 44 45The magic file can be used with the mapping file (option -map) - the order 46these options appear on the command line is important. mkhybrid will try to 47detect if the file is one of the Unix/Mac files (e.g. a CAP or Netatalk 48file) first. If that fails, it will then use the magic and/or mapping 49file e.g: 50 51mkhybrid -o output.raw -map mapping -magic magic src_dir 52 53The above will check filename extensions first, if that fails to set the 54CREATOR/TYPE, the magic file will be used. To check the magic file 55before the filename extensions, use: 56 57mkhybrid -o output.raw -magic magic -map mapping src_dir 58 59 60Using just a magic file - filename extensions will not be checked e.g: 61 62mkhybrid -o output.raw -magic magic src_dir 63 64For the magic method to work, each file must be opened and read twice 65(once to find it's CREATOR/TYPE, and a second time to actually copy the 66file to the CD image). Therefore the -magic option may significantly 67increase processing time. 68 69If a file's CREATOR/TYPE is not set via the magic and mapping matches, 70then the file is given the default CREATOR/TYPE. 71