DESCRIPTION

       This  manual page documents the format of the magic file as used by the
       file(1) command, version 3.22. The file command identifies the type  of
       a  file  using,  among  other tests, a test for whether the file begins
       with a certain magic number.  The file  /usr/local/etc/magic  specifies
       what  magic  numbers  are  to be tested for, what message to print if a
       particular magic number is found, and additional information to extract
       from the file.

       Each  line  of  the file specifies a test to be performed.  A test com-
       pares the data starting at a particular  offset  in  the  file  with  a
       1-byte,  2-byte, or 4-byte numeric value or a string.  If the test suc-
       ceeds, a message is  printed.   The  line  consists  of  the  following
       fields:

       offset   A number specifying the offset, in bytes, into the file of the
                data which is to be tested.

       type     The type of the data to be tested.  The possible values are:

                byte     A one-byte value.

                short    A two-byte value (on most systems) in this  machine's
                         native byte order.

                long     A four-byte value (on most systems) in this machine's
                         native byte order.

                string   A string of bytes.

                date     A four-byte value interpreted as a unix date.

                beshort  A two-byte value (on most systems) in big-endian byte
                         order.

                belong   A  four-byte  value  (on  most systems) in big-endian
                         byte order.

                bedate   A four-byte value (on  most  systems)  in  big-endian
                         byte order, interpreted as a unix date.

                leshort  A  two-byte  value (on most systems) in little-endian
                         byte order.

                lelong   A four-byte value (on most systems) in  little-endian
                         byte order.

                ledate   A  four-byte value (on most systems) in little-endian
                         byte order, interpreted as a unix date.

       The numeric types may optionally be followed by & and a numeric  value,
       to specify that the value is to be AND'ed with the numeric value before
              from the file must have set all of the bits that are set in  the
              specified value, ^, to specify that the value from the file must
              have clear any of the bits that are set in the specified  value,
              or  x, to specify that any value will match. If the character is
              omitted, it is assumed to be =.

              Numeric values are specified in C form; e.g.  13 is decimal, 013
              is octal, and 0x13 is hexadecimal.

              For  string values, the byte string from the file must match the
              specified byte string.  The operators =, < and > (but not &) can
              be  applied to strings.  The length used for matching is that of
              the string argument in the magic file.  This means that  a  line
              can  match any string, and then presumably print that string, by
              doing >\0  (because  all  strings  are  greater  than  the  null
              string).

       message
              The  message  to  be printed if the comparison succeeds.  If the
              string contains a printf(3S)  format  specification,  the  value
              from  the file (with any specified masking performed) is printed
              using the message as the format string.

       Some file formats contain additional information which is to be printed
       along  with  the  file  type.  A line which begins with the character >
       indicates additional tests and messages to be printed.  The number of >
       on  the  line  indicates the level of the test; a line with no > at the
       beginning is considered to be at level 0.  Each line at  level  n+1  is
       under  the  control of the line at level n most closely preceding it in
       the magic file.  If the test on a line at level n succeeds,  the  tests
       specified  in  all the subsequent lines at level n+1 are performed, and
       the messages printed if the tests succeed.  The next line  at  level  n
       terminates  this.   If  the first character following the last > is a (
       then the string after the parenthesis is  interpreted  as  an  indirect
       offset.  That means that the number after the parenthesis is used as an
       offset in the file. The value at that offset is read, and is used again
       as   an  offset  in  the  file.  Indirect  offsets  are  of  the  form:
       ((x[.[bsl]][+-][y]).  The value of x is used as an offset in the  file.
       A  byte,  short  or  long is read at that offset depending on the [bsl]
       type specifier. To that number the value of y is added and  the  result
       is used as an offset in the file. The default type if one is not speci-
       fied is long.

       Sometimes you do not know the exact  offset  as  this  depends  on  the
       length  of  preceding fields. You can specify an offset relative to the
       end of the last uplevel field (of course this may only be done for sub-
       level  tests,  i.e.  test beginning with > ). Such a relative offset is
       specified using & as a prefix to the offset.

BUGS

       The formats  long,  belong,  lelong,  short,  beshort,  leshort,  date,
       bedate,  and ledate are system-dependent; perhaps they should be speci-