文件头魔数
小于 1 分钟
文件头魔数
很多类型的文件，其起始的几个字节的内容是固定的（或是有意填充，或是本就如此）。
根据这几个字节的内容就可以确定文件类型，因此这几个字节的内容被称为魔数 (magic number)。
| file type | suffix | magic |
|---|---|---|
| JPEG | jpg;jpeg | 0xFFD8FF |
| PNG | png | 0x89504E470D0A1A0A |
| GIF | gif | GIF8 |
| TIFF | tif;tiff | 0x49492A00 |
| TIFF | tif;tiff | 0x4D4D002A |
| AOL ART | art | 0x4A47040E000000 |
| AOL ART | art | 0x4A47030E000000 |
| PC Paintbrush | pcx | 0x0A050108 |
| Graphics Metafile | wmf | 0xD7CDC69A |
| Graphics Metafile | wmf | 0x01000900 |
| Graphics Metafile | wmf | 0x02000900 |
| Enhanced Metafile | emf | 0x0100000058000000 |
| CAD | dwg | 0x41433130 |
| Outlook Express | dbx | 0xCFAD12FE |
| MS Office/OLE2 | doc;xls;dot;ppt;xla;ppa;pps;pot;msi;sdw;db | 0xD0CF11E0A1B11AE1 |
| WordPerfect | wpd | 0xFF575043 |
| Quicken | qdf | 0xAC9EBD8F |
| QuickBooks Backup | qbb | 0x458600000600 |
| Sage | sly.or.srt.or.slt;sly;srt;slt | 0x53520100 |
| Lotus WordPro v9 | lwp | 0x576F726450726F |
| Lotus 123 v9 | 123 | 0x00001A00051004 |
| Lotus 123 v5 | wk4 | 0x00001A0002100400 |
| Lotus 123 v3 | wk3 | 0x00001A0000100400 |
| Lotus 123 v1 | wk1 | 0x2000604060 |
| Windows Password | pwl | 0xE3828596 |
| ZIP Archive | zip;jar | 0x504B0304 |
| ZIP Archive (outdated) | zip | 0x504B3030 |
| GZ Archive | gz;tgz | 0x1F8B08 |
| ARJ Archive | arj | 0x60EA |
| MPEG | mpg;mpeg | 0x000001BA |
| MPEG | mpg;mpeg | 0x000001B3 |
| Windows Media | asf | 0x3026B2758E66CF11 |
| ELF Executable | elf;; | 0x7F454C4601010100 |
| Java-Class | class | 0xCAFEBASE |