GnuWin32工具以及一系列其他Unix工具都有。

如果你能找到一个免费的Pascal编译器，你就可以编译它。至少它可以工作，并且显示了必要的算法。

program Whence (input, output);
  Uses Dos, my_funk;
  Const program_version = '1.00';
        program_date    = '17 March 1994';
  VAR   path_str          : string;
        command_name      : NameStr;
        command_extension : ExtStr;
        command_directory : DirStr;
        search_dir        : DirStr;
        result            : DirStr;


  procedure Check_for (file_name : string);
    { Check existence of the passed parameter. If exists, then state so   }
    { and exit.                                                           }
  begin
    if Fsearch(file_name, '') <> '' then
    begin
      WriteLn('DOS command = ', Fexpand(file_name));
      Halt(0);    { structured ? whaddayamean structured ? }
    end;
  end;

  function Get_next_dir : DirStr;
    { Returns the next directory from the path variable, truncating the   }
    { variable every time. Implicit input (but not passed as parameter)   }
    { is, therefore, path_str                                             }
    var  semic_pos : Byte;

  begin
      semic_pos := Pos(';', path_str);
      if (semic_pos = 0) then
      begin
        Get_next_dir := '';
        Exit;
      end;

      result := Copy(Path_str, 1, (semic_pos - 1));  { return result   }
      { Hmm! although *I* never reference a Root drive (my directory tree) }
      { is 1/2 way structured), some network logon software which I run    }
      { does (it adds Z:\ to the path). This means that I have to allow    }
      { path entries with & without a terminating backslash. I'll delete   }
      { anysuch here since I always add one in the main program below.     }
      if (Copy(result, (Length(result)), 1) = '\') then
         Delete(result, Length(result), 1);

      path_str := Copy(path_str,(semic_pos + 1),
                       (length(path_str) - semic_pos));
      Get_next_dir := result;
  end;  { Of function get_next_dir }

begin
  { The following is a kludge which makes the function Get_next_dir easier  }
  { to implement. By appending a semi-colon to the end of the path         }
  { Get_next_dir doesn't need to handle the special case of the last entry }
  { which normally doesn't have a semic afterwards. It may be a kludge,    }
  { but it's a documented kludge (you might even call it a refinement).    }
  path_str := GetEnv('Path') + ';';

  if (paramCount = 0) then
  begin
    WriteLn('Whence: V', program_version, ' from ', program_date);
    Writeln;
    WriteLn('Usage: WHENCE command[.extension]');
    WriteLn;
    WriteLn('Whence is a ''find file''type utility witha difference');
    Writeln('There are are already more than enough of those :-)');
    Write  ('Use Whence when you''re not sure where a command which you ');
    WriteLn('want to invoke');
    WriteLn('actually resides.');
    Write  ('If you intend to invoke the command with an extension e.g ');
    Writeln('"my_cmd.exe param"');
    Write  ('then invoke Whence with the same extension e.g ');
    WriteLn('"Whence my_cmd.exe"');
    Write  ('otherwise a simple "Whence my_cmd" will suffice; Whence will ');
    Write  ('then search the current directory and each directory in the ');
    Write  ('for My_cmd.com, then My_cmd.exe and lastly for my_cmd.bat, ');
    Write  ('just as DOS does');
    Halt(0);
  end;

  Fsplit(paramStr(1), command_directory, command_name, command_extension);
  if (command_directory <> '') then
  begin
WriteLn('directory detected *', command_directory, '*');
    Halt(0);
  end;

  if (command_extension <> '') then
  begin
    path_str := Fsearch(paramstr(1), '');    { Current directory }
    if   (path_str <> '') then WriteLn('Dos command = "', Fexpand(path_str), '"')
    else
    begin
      path_str := Fsearch(paramstr(1), GetEnv('path'));
      if (path_str <> '') then WriteLn('Dos command = "', Fexpand(path_str), '"')
                          else Writeln('command not found in path.');
    end;
  end
  else
  begin
    { O.K, the way it works, DOS looks for a command firstly in the current  }
    { directory, then in each directory in the Path. If no extension is      }
    { given and several commands of the same name exist, then .COM has       }
    { priority over .EXE, has priority over .BAT                             }

    Check_for(paramstr(1) + '.com');     { won't return if file is found }
    Check_for(paramstr(1) + '.exe');
    Check_for(paramstr(1) + '.bat');

    { Not in current directory, search through path ... }

    search_dir := Get_next_dir;

    while (search_dir <> '') do
    begin
       Check_for(search_dir + '\' + paramstr(1) + '.com');
       Check_for(search_dir + '\' + paramstr(1) + '.exe');
       Check_for(search_dir + '\' + paramstr(1) + '.bat');
       search_dir := Get_next_dir;
    end;

    WriteLn('DOS command not found: ', paramstr(1));
  end;
end.

我在互联网上找到的Unix Win32端口没有一个是令人满意的，因为它们都有一个或多个缺点：

不支持Windows PATHEXT变量。（它定义了在扫描路径之前隐式添加到每个命令的扩展列表，以及顺序。）（我使用了很多tcl脚本，没有公开可用的工具可以找到它们。）不支持cmd.exe代码页，这会使它们错误地显示带有非ascii字符的路径。（我对此非常敏感，我的名字中有一个ç：-）cmd.exe和PowerShell命令行中不支持不同的搜索规则。（没有公开可用的工具可以在PowerShell窗口中找到.ps1脚本，但在cmd窗口中找不到！）

所以我最终写了我自己的，这正确地支持了以上所有内容。

此处可用：http://jf.larvoire.free.fr/progs/which.exe

在Windows PowerShell中：

set-alias which where.exe

Windows Server 2003及更高版本（即Windows XP 32位之后的任何版本）提供了where.exe程序，该程序可以执行某些操作，尽管它匹配所有类型的文件，而不仅仅是可执行命令。（它与内置的shell命令（如cd）不匹配。）它甚至会接受通配符，因此nt*可以在%PATH%和当前目录中查找名称以nt开头的所有文件。

尝试在哪里/？寻求帮助。

请注意，Windows PowerShell将where定义为where-Object cmdlet的别名，因此如果需要where.exe，则需要键入全名，而不是省略.exe扩展名。或者，您可以为其设置别名：

Set-Alias which where.exe

更新：建议使用Get命令（别名：gcm），因为它是PS的本机命令，并将获取所有命令类型：别名、cmdlet、可执行文件和函数。例子：

gcm notepad*

对于Windows XP用户（他们没有内置where命令），我编写了一个“where like”命令作为一个名为whicher的rubygem。

要安装它，请安装Ruby。

Then

gem install whichr

运行方式如下：

C： >其中的命令