Archive for March, 2010

SUID [Set User ID] – SGID – [Set Group ID]

SUID – [Set User ID]

SUID bit is set for files (mainly for scripts).
The SUID permission makes a script to run as the user who is the owner of the script, rather than the user who started it.

If “xarabas” is the owner of the script and “mandrake” tries to run the same script, the script runs with the ownership of “xarabas“.
If the root user wants to give permissions for some scripts to run by different users, he can set the SUID bit for that particular script.
So if any user on the system starts that script, it will run under the root ownership.

root user much be very carefull with this.


SGID – [ Set Group ID ]

If a file is SGID, it will run with the privileges of the files group owner, instead of the privileges of the person running the program.
This permission set also can make a similar impact. Here the script runs under the groups ownership.

You can also set SGID for directories.
Consider you have given 2777 permission for a directory.
Any files created by any users under this directory will come as follows.

-rw-rw-r– 1 mandrake LP1 0 Jun 11 17:30 1.txt

In the above example you can see that the owner of the file 1.txt is “mandrake” and the group owner is “LP1“.
So both “mandrake” and “LP1” will have access to the file 1.txt.

Now lets make this more intresting and complicated.
Create a directory “test“. Chmod it to 2777. Add sticky bit to it.

mkdir test
chmod 2777 test
chmod +t test

ls -al test
drwxrwsrwt 2 xarabas LP1 4096 Jun 13 2008 test

From the above permission set you can understand that SGID and sticky bit is set for the folder “test”.
Now any user can create files under the test directory.

drwxrwsrwt 2 xarabas LP1 4096 Jun 13 2008 .
-rw-rw-r– 1 mandrake LP1 0 Jun 11 17:30 1.txt
-rw-rw-r– 1 batman LP1 0 Jun 11 17:30 2.txt
-rw-rw-r– 1 joker LP1 0 Jun 11 17:30 3.txt

So all the “xarabas” user has access to all the files under the test directory.
He can edit, rename or remove the file.
mandrake” user has access to 1.txt only, “batman” has access to 2.txt only…

If sticky bit was not set for the test directory, any user can delete any files from the test directory, since the test directory has 777 permissions.
But now it not possible.

If “joker” tries to remove 1.txt
rm -f 1.txt
rm: cannot remove ‘1.txt’: Operation not permitted

Categories: Linux, Unix

Sticky bit

Sticky bit

The most common use of the sticky bit today is on directories.
When the sticky bit is set, only the item’s owner, the directory’s owner, or the superuser can rename or delete files. Without the sticky bit set, any user with write and execute permissions for the directory can rename or delete contained files, regardless of owner.
Typically this is set on the /tmp directory to prevent ordinary users from deleting or moving other users’ files

Consider you have a directory “/test“.
The chmod it to “777“, this command gives permissions for all the users to read, write and execute.
If you run chmod +t /test and now the /test directory content is the following:

Example: ls -al /test
drwxrwxrwt 2 xarabas LP1 4096 Jun 13 2008 .
-rw-rw-r– 1 xarabas LP1 0 Jun 11 17:30 1.txt
-rw-rw-r– 1 mandrake LP2 0 Jun 11 22:52 2.txt

From the above example “xarabas” is the owner of the test directory (see the first row). “xarabas” can delete or rename the files 1.txt and 2.txt. “mandrake” can delete or rename the file 2.txt only.

Concluding, if the sticky bit is set for a /test directory, only the owner of that directory or the owner of a file can delete or rename a file within that directory.

Categories: Linux, Unix



WinDirStat is a free diagnostic program designed to provide a clear graphical information on the state of distribution of space on hard drives. The program is very useful, it allows select the drives or folders to scan and then go to monitoring of files.
Just finished the analysis, all contents are represented graphically by a series of colored rectangles on the size related to the space occupied on your hard disk. These information provides an immediate visual perception of the whole, to explain better the gigabyte of our hard disk.
WinDirStat provides a valuable help to keep under control so precisely the used space on your personal computer, allowing to find what software is that maybe we had forgotten, that phagocyte megabytes.
The interesting features of WinDirStat are many, among them reveals the intuitive graphical interface that offers the possibility of delete files directly from the display window.

License: Freeware



How to change Microsoft Windows 7 product key

26 March 2010 1 comment

How to change Microsoft Windows 7 product key

Method 1: Manual

1. Right Click on My Computer and Select Properties.

2. Wait a second for windows activation details to get populated.

3. Click on Change Product key link after your Windows 7 activation details are populated.

4. Enter New Product Key and click on next to activate your windows 7

Method 2: Command Prompt

1. Click on start and type command (cmd) with run as administrator option or check how to open elevated command prompt

2. Now type following command

“slmgr.vbs -ipk <insert your new product key here>”

3. To activate windows after changing the key, run “slmgr.vbs -ato”

My Money Express

My Money Express
SlowBit solution for the management of their household budget and all types of accounts.
My Money Express, as well as innovative money management,  is proposed with features found only in software not free.
The Management through Methods and Operations creates a learning slight curve allows you to manage fully automatic movements including the automatic data value for credit card and ATM fees for withdrawals or credit card.
The Help Ask section will give you the answers for your questions of management and use of software.
Now also in portable version installable on USB key to take you data always with you

OS: Windows, Mac and Linux

License: Freeware



My Money Express 2.3.1:



CDBurnerXP is an easy to use and free application to burn CDs and DVDs, including Blu-Ray and HD-DVDs. It also includes the feature to burn and create ISOs, as well as a multilanguage interface. You can create data and audio CDs with or without gaps between tracks, burn and create ISO files, create bootable discs. It does however support Burn-Proof technology, multi-session disks, import of ISO images has bin/nrg – ISO converter, simple cover printing and much more. In addition to CD/DVD burning, you can also rip audio CDs, normalize WAV files, encode MP3 files, erase disks. Compatible with Windows 2000/XP/2003 Server/Vista/7 operating systems. Everyone, even companies, can use it for free. It does not include adware or similar malicious components.

Create Data-CDs/DVDs:

  • burn any Data on CD-R/CD-RW/DVD+R/DVD-R/DVD+RW/DVD-RW, including double layer mediums
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  • copy data discs (possible copy-protection is not bypassed)
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ISO features:

  • burn ISO files to CD
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  • save CDs/DVDs as ISO file to disc

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  • simple cover printing feature for data- and audio-discs
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SO: Windows All; .NET Framework 2.0 (or any higher version)

Size: 4.4MB

License: Freeware



LiberKey Ultimate

LiberKey Ultimate

Liberkey is a collection of portable apps in a variety of categories that can be run on your local PC or from any portable media. Take these important apps with you and use on any computer.

* 100% mobility with portable applications
* A rigorous selection among more than 1800 applications
* Updates of LiberKey directly by Internet
* You can temporarily associate files extensions (.avi, .jpg, doc.,…) with LiberKey applications
* And, it is free, without virus, spyware, adware, popup, etc.

LiberKey Ultimate includes 168 free programs in the following categories:
* Audio
* File Management
* Graphics
* Internet
* Network
* Office
* Security
* System Utils
* Video

The complete list of all programs available on LiberKey:

OS: Windows 2000/XP/Vista/7

Size: 209MB

License: Freeware


Download (english version):

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