Sharing files between VirtualBox host OS and and guest OS

How to share files between host OS and guest OS in VirtualBox.
Host OS: Windows 7
Guest OS: Linux version Ubuntu

Create Shared Folder. Settings -> Shared Folders. Click on add icon, specify Folder Path and Folder Name, check Auto-mount. Folder Path is path on Host OS to be shared. Folder Name is a reference used by guest OS.
VirtualBox will create folder sf-[Folder Name] under /media .
There is a pitfall here. This directory is not accessible. Access permission to this directory is  not given by default to the user who install VirtualBox and set up Shared Folder.
Here is instruction of how to grant the access permission to this directory (see )

1. Open a terminal.
2. Enter "su -" (without quotes), hit Enter.
3. Enter the root password, hit Enter.
4. Type in "usermod -a -G vboxsf username", without quotes, replacing username with the user you want to add to the group, hit Enter.
5. You may have to reboot to remount the share, the easiest way to do this is probably to reboot the VM.

Permutation algorithms

Find out all possible permutation of set of string.

We assume that a given set is lexicographical sorted set.

Algorithm of finding next permutation (we start with original element)
step 1 find left atom
step 2 find right element
step 3 swap
step 4 reverse the order of tail of index of left element (before swapping)


Find left atom. Start with next to the last atom. Move left until the current atom is less then next to it atom. This atom will be left atom.
Find right atom. Start with the last atom. Move left until the current element is great found  left element.

Example. Next to the element { "1" "3" "5" "4" "2" "0" }
                                                       |            |
1 step - left is "3", atoms[1] (current atom "5" less then "3")
2 step - right is "4", atoms[3] (atom "4" is great then "3")
3 step - "1" "4" "5" "3" "2" "0"
4 step - "1" "4" "0" "2" "3" "5" (reverse tail of atoms[1] )

Example.  A B C

1. left = B right = C.
    A C B -> A C B
2. left = A right = B
    B C A -> B A C
3. left = A right = C
    B C A -> B C A
5. left = B right = C
    C B A =>C A B
6. left = A right=B
    C B A => C B A

Code

public StringPerm Successor()
{
  StringPerm result = new StringPerm(this.element);
  int left, right;

  // Step #1 - Find left value 
  left = result.order - 2;  
  while ((result.element[left].CompareTo(result.element[left + 1])) >= 0
         && (left >= 1))
  {
    --left;
  }
  if ((left == 0) &&
      (this.element[left].CompareTo(this.element[left + 1])) >= 0)
  {
    return null;
  }

  // Step #2 - find right; first value > left
  right = result.order - 1;
  while (result.element[left].CompareTo(result.element[right]) >= 0)
  {
    --right;
  }

  // Step #3 - swap [left] and [right]
  string temp = result.element[left];
  result.element[left] = result.element[right];
  result.element[right] = temp;

  // Step #4 - reverse order the tail
  int i = left + 1;        
  int j = result.order - 1;
  while (i < j)
  {
    temp = result.element[i];
    result.element[i++] = result.element[j];
    result.element[j--] = temp;
  }

  return result;
}

Use recursion to get all permutation.

Here is a good article
   

How to get SID of Windows user group

Use utility psgetsid.exe. It is part  of PSTools package.

Ex. psgetsid.exe Adminitrator

Useful command

1. Run as
runas /user:mkalai [executable]

2. Start and stop remote service from command line

sc \\machine stop <service>

sc \\machine start <service>

Example
C:>net  start "Ariel Document Mailing Dispatch Services"
Y:\>sc \\cm-pp-mts01 start "Ariel Document Mailing Dispatch Services"
Y:\>sc \\cm-pp-mts01 stop "Ariel Document Mailing Dispatch Services"

3. Finding info about your PC
systeminfo

Tips for Launching WCF Test Client

When you create WCF Service Library project the command Debug gets set as follows
Start Action: Start Project
Start Options
      Command line arguments:  /client:"WcfTestClient.exe"

When you want to launch your own client set specify your executable for /client switch and set Working directory to where the executable resides