Category Archives: Operating Systems

Windows : How to remove license key and unregister

You may require sometimes to remove the license from a Windows installation, whatever this is to re-assign a license to another machine, or before publishing an appliance, etc. Follow this procedure to put back your Windows installation to the original installation state, license wise. The following commands need to be performed with the Command Prompt… Read More »

Linux : There is no screen to be resumed matching …

Using “screen” on Linux to perform your important work? Way to go, SysAdmin 🙂 Then you might at some point encountered the following behavior – while attempting to resume a session using “screen -r”, the following message occurred : There is a screen on: (25/08/18 08:25:36 PM) (Attached) There is no screen to be… Read More »

Linux : How to get hardware serial number

The easiest way to get hardware serial and related information is using “dmidecode“. The command below should give you exactly what you need :

The command above does not usually work with “clone” computers/servers. Alternatively, you may use the command below, which will output all parts serial number availables :


Windows : How to retrieve Fiber Channel interface WWNs

Here is a simple PowerShell command that will output the FC host adapter interface WWNs.

If your interface have two ports, both will be output in order. This command have been successfully tested with QLogic adapters on Windows 2012 and 2016.

Windows : How To get the members of a group in Active Directory using PowerShell

Here is some useful commands to list the members of a group in Active Directory using PowerShell. Get members of a group :

Get members of a group, recursively (to list all members of sub-groups members of that group) :

NOTE : Replace “Group Name” (keeping the double quotes) with the desired Group… Read More »

Linux : R1Soft The following signatures couldn’t be verified because the public key is not available

Getting this error from the R1Soft repo lately trying to run a “apt-get update” on Debian Linux? Ign stable Release W: GPG error: stable Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 39A4965166BD1D82 Simply do the following to import the new key and get rid of… Read More »

Windows : File Explorer don’t refresh

I had this strange issue on Windows 8/10 where changes such as file/folder renaming or deletion not appearing after a modification. A manual “Refresh” from the contextual menu (right click + Refresh) was required to show the last modification. It seem that some Windows core components were corrupted and needed to be repaired/restored. First of… Read More »