How to grant permission to users for a directory using command line in Windows?

How can I grant permissions to a user on a directory (Read, Write, Modify) using the Windows command line?

Solution

As of Vista, cacls is deprecated. Here's the first couple of help lines:

C:\>cacls
NOTE: Cacls is now deprecated, please use Icacls.

Displays or modifies access control lists (ACLs) of files

You should use icacls instead. This is how you grant John full control over D:\test folder and all its subfolders:

C:\>icacls "D:\test" /grant John:(OI)(CI)F /T

According do MS documentation:

F = Full Control
CI = Container Inherit - This flag indicates that subordinate containers will inherit this ACE.
OI = Object Inherit - This flag indicates that subordinate files will inherit the ACE.
/T = Apply recursively to existing files and sub-folders. (OI and CI only apply to new files and sub-folders). Credit: comment by @AlexSpence.

For complete documentation, you may run "icacls" with no arguments or see the Microsoft documentation here and here