The /etc/magic file is used by commands such as the following to determine the type of a given file:
Entering the following command would result in a printed message describing the file type of the FileName parameter:
file FileName
If FileName contains a byte pattern corresponding to an executable file, the pattern would match a stanza in the /etc/magic file and the executable message would be displayed. If the FileName is a data file, a data message is displayed, and so on.
The fields of the magic file are as follows:
Numeric values may be decimal, octal, or hexadecimal. Strings can be entered as hexadecimal values by preceding them with '0x'.
The last string can have one printf format specification.
The > (greater than) symbol in occasional column 1s is magic; it forces commands to continue scanning and matching additional lines. The first line not marked with the > sign terminates the search.
0 short 2345 this is a dummy type file
0 long 0x1234 this is a different dummy type file
>12 long >0 another possible type
0 short 7895 last type of file
The file command, more or page command.