EXE
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{{Infobox file format | name = Executable | extension = .exe | mime = | owner = | creatorcode = | genre = Binary, executable | containerfor = | containedby = | extendedfrom = | extendedto = }} EXE is the common filename extension for denoting an executable file (a program) in the MS-DOS, Microsoft Windows, and OS/2 operating systems. Generally, "exe" may be used as a noun to refer to such a file.
There are several main EXE file formats.
- DOS executable: These can only be identified by the ASCII string "MZ" or the hexadecimal 4D 5A at the beginning of the file (the "Magic number"). These executables are the least complex in DOS/Windows and can be run from both ("MZ" are the initials of Mark Zbikowski, one of the developers of MS-DOS).
- 16-bit New Executable: These can be identified by the "NE" in ASCII. These cannot be run by DOS but can be run by all Windows and OS/2 versions.
- Mixed 16/32-bit Linear Executable: These can be identified by the "LE" in ASCII. This format is not used for applications, but instead for VxD drivers under Windows 3.x and Windows 9x.
- 32-bit Linear Executable: These can be identified by the "LX" in ASCII. These can only be run by OS/2 2.0 and higher. They are also used by some DOS extenders.
- 32-bit Portable Executable: These are the most complex and can be identified by the "PE" in ASCII. These can be run by all versions of Windows NT, and also Windows 95 and higher. They are also used in BeOS R3, however they somewhat violate the PE specification as they don't specify a correct subsystem.
- 64-bit: These are similar to PE files, but make use of 64-bit extensions supported by the CPU. These can only be run by 64-bit editions of Microsoft Windows, such as Windows XP 64-Bit Edition or Windows Server 2003 64-Bit Edition.
Besides them, there are also many custom EXE formats, such as W3 (a collection of LE files, only used in WIN386.EXE), W4 (a compressed collection of LE files, only used in VMM32.VXD), DL, MP, P2, P3 (last three used by Phar Lap extenders), and probably more.
When a 16-bit or 32-bit executable is run by Windows, execution starts at either the NE or the PE. On the other hand, DOS cannot execute these files. To prevent DOS from crashing, all Windows executable files must start with a working DOS program. Normally this program simply displays a message that it cannot run in DOS mode, but some Windows programs (such as regedit) have a usable DOS section.