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Create a program that returns a truthy value when run on Microsoft Windows (for simplicity we'll stick with Windows 7, 8.1 and 10) and a falsey value when run on any other operating system (OSX, FreeBSD, Linux).
I'm labelling this as code-golf, so lowest score wins, but I'm also very interested in seeing creative solutions to this problem.
ispc
From the documentation:
tf = ispcreturns logical 1 (true) if the version of MATLAB® software is for the Microsoft® Windows® platform. Otherwise, it returns logical 0 (false).
There are also the functions ismac and isunix. I'll leave it to the reader to figure out what those functions do. Mego kindly asked for diagrams explaining ismac and isunix so I've tried to illustrate it here:
It was not asked for a diagram of ispc but I can reveal that the behaviour is pretty similar, except substitute OSX and Unix with Windows.
Second approach:
Here's a second approach with getenv using 23 bytes that should be bullet proof, unless there's another operating system starting with W:
x=getenv('OS');x(1)==87
getenv 'name'searches the underlying operating system environment list for text of the formname=value, wherenameis the input character vector. If found, MATLAB® returns the character vector value. If the specified name cannot be found, an empty matrix is returned.
<C-a>1
On Windows, <C-a> (ctrl+a) is mapped by default to Select All. If you type a 1 in select mode in Windows, it replaces the selection with what you typed (1) leaving a 1 in the buffer.
On other operating systems, <C-a> by default is mapped to Increment number. Because there's no number to increment, it's a no-op, and then the 1 increases the count but in terms of the buffer is a no-op.
1 is truthy in Vim, and an empty string is falsy
Ctrl + a, 1. If it were Ctrl + a + 1 it'd be counted as 1 keystroke.
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Jan 9, 2017 at 21:34
import os
0/('['>os.sep)
Thanks to FlipTack for 3 bytes
This program takes advantage of the fact that Windows is the only OS to use \ as a path separator. Normally this is frustrating and bad, but for once it is actually an advantage. On Windows, '['>os.sep is false, and thus 0/0 is computed, causing a ZeroDivisionError and exiting with a non-zero exit code. On non-Windows platforms, '['>os.sep is true, making the expression 0/1, which does nothing, and the program exits with exit code 0.
31 DB 89 D8 40 CD 80
Or
xor ebx, ebx
mov eax, ebx
inc eax
int 0x80
First of all, we'll set eax to 1 (the system call number for exit(int val) for Linux, FreeBSD and OSX).
Then, we'll call the interrupt gate 0x80 which is the system call gate for Linux, FreeBSD and OSX. That would cause the program to exit with status of ebx which is 0 (false).
On Windows int 0x80 is an invalid gate (It uses 2e as a syscall gate) and would crash the program, causing it to end with a positive exit code (true).
Edit: Would not work on OSX since it has a different argument-passing convention on 32 bit (by the stack).
FreeBSD - System Calls: Information about system calls in FreeBSD.System calls in the Linux kernel. Part 2.: A great article about Linux's system calls.Linux Syscall Reference: a system call numbers reference for Linux.Windows Syscall Shellcode : An article about directly calling system calls in windows from assembly.Making system calls from Assembly in Mac OS X: An article about system calls on OSX.
xor eax, eax in there?
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Jan 9, 2017 at 22:13
false exits with code 1 whilst true exits with code 0).
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eax and ebx are cleared to zero on program start (on non-Windows), which is not guaranteed if I remember correctly. It also explicitly assumes that the syscall argument-passing convention for Linux matches that for FreeBSD and OSX, which would be very surprising indeed.
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mov eax, 1 would be translated to \xB8\x01\x00\x00\x00, which is a lot longer that just moving register and calling inc.
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Jan 13, 2017 at 12:48
`<?=PATH_SEPARATOR>":";`
prints 1 if the path separator is semicolon (colon or empty for all other OSs except for DOS and OS/2), else nothing.
also 22 bytes, but not that safe:
<?=strpos(__FILE__,92);
prints a positive integer if the file path contains a backslash; else nothing.
A safe alternative with 27 bytes: <?=DIRECTORY_SEPARATOR>"/"; prints 1 or nothing.
A strange find: <?=__FILE__[1]==":"; (20 bytes) should be, not safe either, but ok.
But although __FILE__ pretends to be a string (I tried var_dump and gettype), indexing it throws an error, unless you copy it somewhere else (concatenation also works) or use it as a function parameter.
Edit:
<?=(__FILE__)[1]==":"; (also 22 bytes) works in PHP 7; but that´s because the parentheses copy the constant´s value to a temporary variable.
27 bytes: <?=stripos(PHP_OS,win)===0;
tests if predefined PHP_OS constant starts with win (case insensitive; Windows,WIN32,WINNT, but not CYGWIN or Darwin); prints 1 for Windows, else nothing.
17/18 bytes:
<?=strlen("
")-1;
prints 1 if it was stored with Windows linebreak (also on DOS, OS/2 and Atari TOS - although I doubt that anyone ever compiled PHP for TOS), else 0.
You could also check the constant PHP_EOL.
more options:
PHP_SHLIB_SUFFIX is dll on Windows, but not necessarily only there.
php_uname() returns info on the operating system and more; starts with Windows for Windows.
$_SERVER['HTTP_USER_AGENT'] will contain Windows when called in a browser on Windows.
<?=defined(PHP_WINDOWS_VERSION_BUILD); (38 bytes) works in PHP>=5.3
conclusion
The only failsafe way to tell if it´s really Windows, not anything looking like it, seems to be a check on the OS name. For PHP: php_os() may be disabled for security reasons; but PHP_OS will probably always contain the desired info.
<?=class_exists(COM);. The class COM is only available under Windows, as far as I know. That should save you one byte.
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Jan 8, 2017 at 22:28
Thanks to @Downgoat for a byte! crossed out 44 is still regular 44
Thanks to @Neil for two bytes!
f(){return
#ifdef WIN32
!
#endif
0;}
0 out of the ifdef and changing the 1 to !, but I think _WIN32+0 works even better still.
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return 1; inside the ifdef and remove the else, since main without return in c99 must return 0.
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#if WIN32. On non-windows, since WIN32 is not defined, the preprocessor is required to treat it as 0.
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6y2%!.@
This works by querying the system path separator, which is \ on Windows and / on other operating systems.
6y System information query: #6 returns the path separator.
2% Test the low bit - this will be 1 for '/' and 0 for '\'.
! Not the value, so it becomes 0 for '/' and 1 for '\'.
.@ Output the result and exit.
$OperatingSystem=="Windows"&
&, it won't print anything (and it's then also not a callable function, but merely a snippet/expression).
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Jan 8, 2017 at 19:04
Out[1]= False output from this: ~/opt/Mathematica/11.0/Executables/math <<< '$OperatingSystem=="Windows"'
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Special thanks to Olivier Grégoire for suggesting separatorChar, and Kritixi Lithos for -1 byte!
This is a lambda expression which returns a boolean. This can be assigned to Supplier<Boolean> f = ...; and called with f.get().
()->java.io.File.separatorChar>90
Try it online! - the server isn't windows, so this prints false. However, in my windows machine, the same code prints true.
What this code does is get the System's file seperator, and check whether its codepoint is larger than the character [. This true for Windows, as it uses \ as the seperator - but every other OS uses /, which has a lower code in the ASCII table.
()->java.io.File.separatorChar>'['!
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1. When assigning it to a variable, the assignment is a statement and therefore requires the semicolon, like int i = 1; - but the lambda itself doesn't need the semicolon.
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.Platform$O>"v"
Thanks to plannapus for the suggestion to use partial matching for list element extraction.
.Platform is a list with some details of the platform under which R was built. There is an element OS.type (the only element with name starting with "O") which is character string, giving the Operating System (family) of the computer. One of "unix" or "windows".
So "unix" is less then "v", but "windows" is greater then "v". Other valid 15 bytes answers are
.Platform$O>"V"
.Platform$O>"w"
.Platform$O>"W"
R is being developed for the Unix-like, Windows and Mac families of operating systems. Other OS families are not supported.
6=9!:12
This is a verb (similar to a function) that uses the builtin foreign conjunction 9!:12 to acquire the system type where 5 is Unix and 6 is Windows32.
40 39 04 24 75 02 CD 80 C3
Compiled from:
inc eax ; set eax to 1
cmp [esp], eax ; check if [esp] == 1 (linux)
jne windows ; jump over "int 0x80" if on windows
int 0x80 ; exit with exit code 0 (ebx)
windows:
ret ; exit with exit code 1 (eax)
inc eax and int 0x80, I think it should fail on windows and terminate the process.
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Jan 9, 2017 at 15:00
print$^O=~MS
^O should be replaced by a literal Control-O.
Outputs 1 on windows, nothing on another OS.
Note that I'm not using say as it adds a trailing newline, which is truthy in Perl.
-2 bytes thanks to primo. (and fixed potential issues)
-1 bytes thanks to ais523.
^O.
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$^O=~W, although, I would probably match against MS. Alternatively, you could also match $^X=~':'.
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W in it so I assumed checking for a W for fine.. any reasons why you suggest MS instead?
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is_windows
A function that returns true for windows
()=>(int)System.Environment.OSVersion.Platform<4
Saved 13 bytes thanks to TheLethalCoder
Or a full program at 83 bytes:
class P{static int Main(){return(int)System.Environment.OSVersion.Platform<4?1:0;}}
Various Windows variants use enum values 0 to 3 in the Microsoft .NET implementation. 4 is Unix, 5 is Xbox [360] (which I won't consider "Windows"), 6 is MacOSX. Mono uses the same values, adding 128 for Unix/Linux in earlier versions.
Therefore, anything < 4 is Windows, and everything else is not Windows.
int?
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CS0019 Operator '<' cannot be applied to operands of type 'PlatformID' and 'int' -- basically, C#'s typing rules says I can't compare a PlatformID and int directly, and there's no implicit cast from PlatformID to int. But there is an explicit cast from all enums to their values, which I take advantage of here...
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System.Environment.OSVersion at all. If you're going to take issue with that, then you should also delete every other non-UWP answer. It also turns out that you can't (currently) run UWP apps on non-Windows platforms, so you can go delete all those too. Which leaves you with 0 answers, and an unanswerable question.
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Action<bool> in the first example for 48 bytes (I haven't tested it but believe it will work) _=>(int)System.Environment.OSVersion.Platform<4; It might need to be ()=>... for 49 bytes though
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Jan 11, 2017 at 12:58
Funcs and Actions are used all the time here. I believe it's in the golfing tips page and I use them almost all the time. Also anonymous functions are used in other languages a lot so I think it is safe to use them here
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Jan 11, 2017 at 14:23
console.log((
//Begin
_=>navigator.oscpu[0]>'V'
//End
)())Tested with Firefox. (Chrome doesn't have the oscpu property.)
Since lowercase letters have a higher character code than uppercase letters, this depends on the first letter of navigator.oscpu being uppercase and not being W, X, Y or Z on any platform that Firefox supports (other than Windows, of course). According to this post, that is the case.
oscpu is probably the shortest navigator property that you can use. Also, testing a regexp will probably work out shorter, but I haven't measured it.
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!=-1 and add a ~ right after the fat arrow, saving 3 bytes.
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console.log the regex test? Also would navigator.oscpu[0]=='W' work or is there another OS that also starts with W.
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@if %OS%==Windows_NT if not exist Z:\bin\sh echo 1
Edit: Fixed to ignore DOS instead of claiming that it's Windows.
The only other way I know of running Batch outside of Windows is to use WINE which by default will map Z: to /. Therefore if Z:\bin\sh exists, chances are that it's /bin/sh, so not MS Windows.
I don't know what WINE sets %OS% to, but if it's not Windows_NT then I could save 23 bytes.
?INSTR(ENVIRON$("COMSPEC"),"W")
Prints non-zero under Windows, 0 under everything else.
COMSPEC is an environment variable unique to Microsoft OSs. It points to the command interpreter, typically command.com or cmd.exe. Under Windows, the command interpreter sits somewhere in the Windows directory; under MS-DOS, it sits in the DOS directory or on the root of the disk, and under any other OS, it doesn't exist.
By checking to see if the value of COMSPEC contains a "W", we can tell the difference between Windows and not-Windows.
COMSPEC isn't reserved to mean anything in particular under Linux (meaning it's under user control by default), so isn't it possible that the user's set it to a value that they're using for their own purposes (and happens to contain a W)? Admittedly, that's a bit of an edge case.
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Thanks to @Patrick, who shaved 12 bytes off my solution using Node's REPL:
_=>os.EOL>`
`
Original solution:
_=>require('path').sep!='/'
Node.js REPL, you can save 16 bytes by just using _=>path.sep!='/'
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Jan 10, 2017 at 9:44
node on the console. From there, all the system node modules are available without the need to require() them.
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Jan 10, 2017 at 9:48
!= to > since the ASCII index for \ is 92 and / is 47.
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Jan 13, 2017 at 9:13
Immediate windows function that returns true if the system's OS code starts is longer than length 3, because the info is restricted to output either else mac or pcdos this returns true only on windows pcs
?[Len(Info("SYSTEM"))>3]
Previous Versions
''# Ignore the second `"` that follows every `\` - its only there for highlighting
?Left(Environ("OS"),1)="W" # 24 Bytes
?InStr(ThisWorkbook.Path,"\"") # 29 Bytes
?Mid(ThisWorkbook.Path,3,1)="\"" # 30 Bytes, Restricted to local Files
?Application.PathSeparator="\"" # 30 Bytes
?Left(Application.OperatingSystem,1)="W" # 40 Bytes
Changes
-1 Thanks to Neil for using Left(...,1) over Mid(...,1,1)
-10 Thanks to ChrisH for pointing out @Mego's Path Separator Trick
-1 For Checking the WorkbookPath for "\" rather than using Application.Path Separator
-4 For switching to Environ()
-2 For switching to [Len(Info(...
Novel Solution, 51 bytes
Novel subroutine that outputs, to the VBE immediates window, a 1 (truthy) under windows and 0 (falsey) under mac by method of conditional compilation.
Sub a
i=1
#If Mac Then
i=0
#End If
Debug.?i
End Sub
?Application.PathSeparator)="\" would be 32 as it's a single char)
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put $*DISTRO.is-win
put ?($*CWD~~/\\/)
Both output True or False depending on the system it is run on.
rm $0
Also works in most other POSIXy shells. (Note that Windows ports of bash and rm exist; even though they're only normally used with more heavily POSIXy operating systems, this isn't an entirely vacuous entry.) Outputs via exit code (0 = false, 1 = true). Can be counted as 4 bytes if you're allowed to assume a filename (e.g. rm a). Note that this can potentially fail in the case of very weird filenames (which rm will interpret as arguments due to the lack of quoting, and possibly delete files you care about, so I'd advise against running this program from a file with a weird name).
Note: deletes the program from disk as a side effect, or at least tries to. In the case where we're running on Windows, the OS will fail to delete the running file (an operation that Windows disallows either by default or full stop), and thus rm will error out. bash catches the error and converts it into an exit code (thus the program as a whole terminates normally). Most of the other entries here are using 0 for falsey and 1 for truthy in exit codes, so this does the same; note that bash's if statement doesn't accept integers at all (rather, it accepts commands and branches based on whether they run successfully, and arithmetic tests are done via the means of programs like test that intentionally report a "crash" on a failed comparison), so this is on shakier ground in terms of legality than programs that output via exit code in languages where 0 is valid in an if statement test and sends the program to the else branch.
'W'∊∊#⎕WG'APLVersion'
#⎕WG'APLVersion' Root (#) Window Get property APL Version
∊ enlist (flatten)
'W'∊ is W a member? (no non-Windows return values contain a capital W)
America is great.
This program, if run on windows, will print:
The big problem this country has is being PC
This is considered a truthy value.
Empty output and the following value are falsy:
Boycott all Apple products until such time as Apple gives cellphone info to authorities regarding radical Islamic terrorist couple from Cal
The empty output will occur on any linux system (for this program), the long apple response obviously occurs on Mac (for any program). On TIO, the backend (I'm assuming) is a Unix operating system, so you can only get the falsy value; on my computer I get the PC message.
Not 100% sure if this counts as an error message (which would invalidate the answer), but if you didn't know about this it was probably worth a laugh for you.
expr [lsearch $tcl_platform windows]>0
The following will output 1 if windows and nothing if anything else. Ignoring notices of string convertion.
<?=PHP_OS==WINNT;
Try online Online tests for linux because the sandbox is linux for PoC.
>V might work too.
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Jan 9, 2017 at 10:18
()->System.getenv().get("OS").contains("Windows")
Longer than the other Java answer, but takes a different approach.
This lambda fits in a Supplier<Boolean> and can be tested with the following program:
public class DetectMSWindows {
public static void main(String[] args) {
System.out.println(f(() -> System.getenv().get("OS").contains("Windows")));
}
private static boolean f(java.util.function.Supplier<Boolean> s) {
return s.get();
}
}
import System.Info
f=os!!0=='m'
I check for the first letter output of "m", which should be "mingw" for windows. As far as I could tell, there is no other OS which starts with M. The information comes from https://github.com/ghc/ghc/blob/master/compiler/utils/Platform.hs
os gives "mingw32".
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os 1- not .
Prints true on Windows, false on Linux and macOS. Other platforms supported by 8th are Android, iOS and Raspberry Pi, but I am not able to test on them.
Ungolfed version (with comments)
G:os \ Return a number n indicating the operating system
\ 0 for Linux
\ 1 for Windows
\ 2 for macOS
\ 3 for Android
\ 4 for iOS
\ 5 for Raspberry Pi
n:1- \ Subtract 1
G:not \ If Windows --> true, otherwise --> false
. \ Print result
import winreg
Returns with exit code zero (generally true in shells) if on windows, and with a non-zero exit code otherwise.
If you prefer it the other way round, there is a 12 bytes solution: import posix.
winreg.py in the same directory.
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