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NAME    [Toc]    [Back]

       magic - Magic file for the file command

SYNOPSIS    [Toc]    [Back]


DESCRIPTION    [Toc]    [Back]

       The  magic  file  is  used by the file command to identify
       files that have some sort of magic number.  A magic number
       is any numeric or string constant that identifies the file
       containing the constant.

       The format for the magic file is as follows:

            offset   type   operator,value   string

       The fields should be separated by tabs.  Each record  must
       be contained on one line.

       The fields contain the following data: This field contains
       the number of bytes from the  beginning  of  the  file  on
       which  you  are running the file command to the first byte
       of the magic number of character string you want to  identify.
  Use a right angle bracket (>) to indicate a continuation
 line that supplies additional information  describing
  the  file.  This field contains information about the
       data type of the magic number or character string  at  the
       specified  byte  offset.   Valid data types for this field
       are: Unsigned character type Unsigned short type Long type
       Character  (byte)  string This field contains instructions
       for the file command on how to compare the value read from
       the  file being checked with the value stored in the Value
       Type field of the magic file.  The valid comparison operators
 are: The two values are equal.  The value in the file
       being checked is greater than the value in the magic file.
       The value in the file being checked is less than the value
       in the magic file.  All the bits in the magic  file  value
       must be set in the value from the file being checked.

              Note   that   the   Comparison  Operator  field  is
              optional.  If you do not specify the operator,  the
              values  are  expected to be equal.  This field contains
 the value used to compare what is  read  from
              the  file  being  checked by the file command.  You
              can use decimal, hex,  or  octal  numbers  in  this
              field  or  character strings in the form of regular

              Precede all hex numbers with  the  characters  zero
              and x (for example, 0x80). To specify an octal number,
 precede it with a zero  (for  example,  0200).
              Decimal  numbers  require no special representation
              and should be written  as  integers  (for  example,

              The  rules  for specifying character strings follow
              those of the ed  editor  (see  ed(1))  for  regular
              expressions, with two extensions: You use the backslash
 (\) to escape an unprintable character.   The
              string  can  contain  all special character such as
              \n, \b, \r, and \f. If a backslash appears  in  the
              string,  it must be escaped with a second backslash
              (\\).  You can use octal representation to  specify
              any  byte value other than zero (0).  Text found in
              the file can be inserted into the printed string if
              it is preceded and followed by \\% delimiters.  All
              text found between these delimiters is displayed as
              the print string.

              This  regular  expression  search  never terminates
              until a match is explicitly found or rejected.  The
              special  character  \n  is a valid character in the
              patterns.  Therefore, the pattern .*  should  never
              be  used  here.   This field contains the string to
              print. The string provides  information  about  the
              file. The string can include text found in the file
              when requested with an appropriate printf() format.

EXAMPLES    [Toc]    [Back]

       The  following  is  an  example  of  a script: string ^#!{
       }*\\%[^ \n]*\\%     %s

       The  following  are  examples  of  executable  images:  >2
       short    02                      POSIX >2       short   01
       SVID >16      long    >0                     not stripped

       The following are examples  of  text  and  data  files:  0
       string     ^\01h[0-9][0-9][0-9][0-9][0-9]     sccsfile   0
       string   ^#ifndef                          c   program   0
       string     ^070707                            ASCII   cpio

FILES    [Toc]    [Back]



       Commands:  file(1) delim off

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