In windows, how to mount folder as a drive

I have some folder, say C:\foo I want to mount as drive M:\

In linux I would do this with a bind mount.

You can use the subst command in Windows.

subst m: c:\foo

To make a persistent redirection, you can edit the registry. Add a string (REG_SZ) value to:

HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\DOS Devices

Set the name of the value to the drive letter (e.g. M:), then the data to:

\??\C:\foo\foosub

This method will work across logins and reboots. I tested this on Windows 2008, so it should also work on Vista, XP, 2003 and 2000.

Subst also works in Vista:

C:\Users\juan>subst /?
Associates a path with a drive letter.

SUBST [drive1: [drive2:]path]
SUBST drive1: /D

  drive1:        Specifies a virtual drive to which you want to assign a path.
  [drive2:]path  Specifies a physical drive and path you want to assign to
                 a virtual drive.
  /D             Deletes a substituted (virtual) drive.

Type SUBST with no parameters to display a list of current virtual drives

.

• Right-click on the folder and select Sharing and Security
• Select Share this folder
• Give it a share name (eg- myshare)
• hit Ok

Map a drive (M:) to \\yourcomputername\myshare

From the command line:

subst M: C:\foo

This works in Windows XP, haven't tested it in other versions.