magic(5)							File Formats Manual							  magic(5)

Name
       magic - magic file for the file command

Syntax
       /usr/lib/file/magic

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

       The file is formatted as follows:

       Byte offset
	    The byte offset is where information is found in the file. This is the number of bytes from the beginning of the  file  to	the  first
	    byte of the magic number or string. This may, optionally,  be preceded by a right angle bracket (>) to indicate a continuation line to
	    supply extra information in the printed message.

       Value type
	    The value type is the type of the information to be found at the specified byte offset.  The file data is interpreted as the following
	    valid types:

		 byte	  Unsigned char type
		 short	  Unsigned short type
		 long	  Long type
		 string   Character (byte) string

       Optional operator
	    Describes  how  the  value	specified  here should be compared with the data at the desired offset.  Valid operator characters are: an
	    equal sign, a right angle bracket, and a left angle bracket (=, >, <).  If none is specified, = is assumed.

       Value
	    The value to match. Numeric values may be decimal, octal, or hexadecimal.  String values are defined as regular expressions here.  The
	    regular expressions used here are extended in two ways from regular expression definition in ed(1).

		 1.  Normally  unprintable characters may be escaped with a backslash ().  The special characters 
, , 
, and f are allowed.
		     An octal representation can also be used to insert any desired byte value, except 0.   Normally,  regular	expression  cannot
		     handle  such  character  values.	Because the backslash is used as an escape character while the regular expression is being
		     read in, normal occurrences of a backslash in a regular expression must be escaped with a second backslash. As an example, (
		     must be written as \( and . must be written as \.

		 2.  Text  found  in  a file can also be inserted in the printed string with the use of the \% delimiter.  All text found between
		     these delimiters is substituted into the print string.

		     This regular expression search never terminates until a match is explicitly found or rejected.  The special character 
 is a
		     valid character in the patterns.  Therefore, the pattern .*  should never be used here.

       major, minor type
	    The major and minor file type numbers are not used by the command.

       String to print
	    Any  desired  text string.	Data from the file can be included with the use of continuation lines beginning with a right angle bracket
	    (>).  Two types of continuation lines are possible, depending on the sign of the byte offset entry.

	    If the byte offset is positive, the specified data can be printed in the string when requested with an appropriate format.

	    If the offset is a negative number, an internal routine will be called to test if a particular string is  necessary  and,  if  so,	to
	    return it.

	    The  byte  offset number is an index to an internal table of routines available for use. Two such routines are currently defined, both
	    for a.out images:

	    Byte Offset    Returned String(s)

	    -1: 	   ["old version 7 style symbol table"]
	    -2: 	   ["setuid "]["setgid "]["sticky "]

Examples
       The following is an example of a script.  The second line adds setuid, setgid text, if appropriate:
       0   string ^#![ ]*\%[^ 0*\%  7,4   %s
       >-2 long   0			7,4   %sscript
       The following is an example of an executable image:
       >-1 long   0		  12,3	 %s
       0   short  0413		  12,4	 demand paged pure
       >2  short  02		  12,4	 POSIX
       >2  short  01		  12,4	 SVID
       >-2 long   0		  12,4	 %sexecutable
       >16 long   >0		  12,4	 not stripped
       The following is an example of a text file:
       0   string ^ 1h[0-9][0-9][0-9][0-9][0-9]  7,1  sccsfile

Files
See Also
       file(1)

																	  magic(5)