$ echo %pathext%
.COM;.EXE;.BAT;.CMD;.PL

$ which -a foo
D:/junk/foo.COM
D:/junk/foo.COM
D:/junk/foo.EXE
D:/junk/foo.EXE
D:/junk/foo.BAT
D:/junk/foo.BAT
D:/junk/foo.PL
D:/junk/foo.PL