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Getting Rid of Posix in Windows 2000/XP
~~Vic Ferri, WinTips and Tricks

For security reasons, you should disable POSIX if it is present on your system. Posix stands for "Portable Operating System Interface" and, for the majority of users, is a useless subsystem that allows Unix commands to be run on your computer.  In other words, by having Posix running on your system, you allow hackers access to your computer.  Additionally, you are just wasting system resources by allowing Windows to load a subsystem you do not use or need.

To see if you have Posix on your system, search your hard drive for a file named psxss.exe.  The default location would be in your Windows\System32 folder.  If you do have it and want to disable it, follow these steps:

Click Start>Run and type regedt32 (NOT regedit)

Make your way to the SubSystems key which is here:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\SubSystems

You will notice the name of these two string values in the right hand pane:

1. Optional - with Posix as the Data
2. Posix - with the path of the Posix executable, which by default is "%SystemRoot%\system32\psxss.exe", as the Data.

If you do have Posix, here is how to disable it from being used against you:

1. Double click the Optional value and delete the Posix data value so it is empty. Click OK.
2. Right click the Posix string value and choose Delete.
3. Now delete the actual posix file from your computer. As you saw it is named psxss.exe and by default is located in your System32 folder. A quick way to get there is by typing System32 in the Run box.
4. Once deleted, reboot.

Your computer is now a little more secure and a little more efficient.

*NOTE: If you are uncomfortable editing your Registry, I recommend Registry for Newbies which teaches all the basics you will need to know to safely get around in the Windows Registry.

Vic Ferri owns the very popular WinTips and Tricks and Registry Answers.  Subscribe to either and receive free Windows and Registry Tips.  He is also in charge of the Printing Tips  pages at Linda's Computer Stop.  Vic has also created a program which allows you to Lock & Hide desktop folders in Windows 9X/ME.  Read more and get the free demo here.  And, he now offers a service to convert PowerPoint presentations to .exe files which can be viewed on computers which do not have PowerPoint installed.