> shutdown /?
> Usage: shutdown [/i | /l | /s | /r | /g | /a | /p | /h | /e | /o] [/hybrid] [/f]

The windows cmd.exe command shutdown only documents forward slash / switches, but it accepts dash - switches as well. For instance, both work:

shutdown /s /t 0
shutdown -s -t 0

When was this added and why?

closed as not constructive by GrandmasterB, BЈовић, Walter, EL Yusubov, StuperUser Oct 31 '12 at 12:38

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  • 6
    Slashes: Windows's original option syntax. Dashes: To make it more POSIX like – Thomas Eding Oct 30 '12 at 17:22
  • @ThomasEding, not quite "original", it is an RSX-11 (and other similar DEC systems) legacy (through CP/M) – SK-logic Oct 30 '12 at 18:18
  • And (MS|PC)-DOS, which preceded Windows. – Blrfl Oct 30 '12 at 19:06
  • @Blrfl: MS-DOS followed CP/M. – kevin cline Oct 30 '12 at 19:54
  • @kevincline: Windows, having originally been built atop MS-DOS, got its option signifier there. MS-DOS, which started life as Seattle Computer Products' 86-DOS, was a CP/M clone for the 8086. Just filling in the historical gap between CP/M and Windows. – Blrfl Oct 30 '12 at 20:15

I would venture that multiple escape characters are supported for switches so that users that are used to a particular escape character can still use the application from the command-line.


Slashes are Windows's original option syntax and not all windows commands accept the dash-options.

With Dir /? you the list of the options for dir.

But with

Dir -?

you get a file not found-message (tested with Windows XP) (Same with dir -w...).

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