Posts Tagged ‘boot’

Remove old unused kernels and cleanup orphaned packages on CentOS / RHEL/ Fedora and Debian Linux

Friday, October 23rd, 2020

Reading Time: 4minutes


If you administer CentOS 7 / CentOS  8 bunch of servers it is very likely after one of the scheduled Patch days every 6 months or so, you end up with a multiple Linux OS kernels installed on the system.
In normal situation on a freshly installed CentOS machine only one rpm package is installed on the system with the kernel release shipped with CentOS / RHEL / Fedora distro:
The reason to remove the old unused kernels is very simple, you don't want to have a messy installation and after some of the updates to boot up in a revert back old kernel or if you're pedantic to simply save few megas of space.
Some people choose to have more than one kernel just to make sure, if the new installed one doesn't boot, after a restart from ILO / IDRAC remote console interface you can select to boot the proper kernel. I agree having the old kernel before the system *kernel* upgrade as backup recovery is a good thing but this is a good thing to the point the system gets booted after reboot (you know we sysadmins usually after each major system package upgrade), we like to reboot the system warmly praying and hoping it will boot up next time 🙂

1. Remove CentOS last XX kernels from the OS

Of course removal of old kernels could be managed by a simple

yum remove kernel


One more than one kernel is present you can hence leave only lets say the last 2 installed kernel on the CentOS host (some people prefer to have only one) but just for the sake of having a backup kernel I like more to have last two kernels installed present, to do so run package-cleanup which is contained in yum-utils rpm package CentOS – this is CentOS / Redhat ( RHEL) specific command.

[root@centos ~ ]:#package-cleanup –oldkernels –count=2


–count=number argument – tells how many from the  latest version kernels to get removed.

Note if you don't have the package-cleanup command install yum-utils package:

[root@centos ~ :]#  yum install -y yum-utils


2. RemoveOld kernels from Fedora Linux – leave only the latest 3 installed

This is done with dnf by setting the –-latest-limit arg to negative value to how many last kernels want to keep

[root@fedora ~ ]:# dnf remove $(dnf repoquery –installonly –latest-limit=-3 -q)


3. Set how many kernels you want to be present on system all the time after package upgrades

It is possible to tell CentOS / RHEL / Fedora's on how many kernels show be kept installed on the system, the default configured on Operating system install time is to keep the last 5 installed kernel on the OS. This is controlled from installonly_limit=5 value that is usually as of year 2020 RPM based distributions found under /etc/yum.conf (on CentOS / RHEL) and in /etc/dnf/dnf.conf (in Fedora) configuration file and sets the desired number of kernels present on system after issuing commands yum upgrade / dnf upgrade –refresh etc.
The minimum number to give to  installonly_limit is 2.

4. Remove orphan rpm packages from server

The next thing to do is to check the installed orphan packages to see if we can safely remove them; by orphaned packages we mean all packages which no longer serve a purpose of package dependencies.
Orphan packages are packages who left over from some old dependencies that are no longer needed on the system but just take up space and impose a possible security risk as some of them might end up with time with a public well known and hacked CVE vulnearbility.

Let me try to explain this concept with a quick example: package A is depended on package B, thus, in order to install package A the package B must also be installed. Once the package A is removed the package B might still be installed, hence the package B is now orphaned package.
Here’s how we can safely see the orphan packages we do have on our system:

[root@centos ~ :]# package-cleanup –quiet –leaves –exclude-bin

And here’s how we can delete them:

[root@centos ~ :]# package-cleanup –quiet –leaves –exclude-bin | xargs yum remove -y

The above commands should be launched multiple times, because the packages deleted with the first batch could create additional orphan packages, and so on: be sure to perform these tasks until no orphan packages appear anymore after the first package-cleanup command.


5. Delete Old Kernels and keep only last three ones on Debian / Ubuntu Linux

To do the same on a debian based distribution there is a command is provided by a deb package byobu, if you want to clean up old kernels on Debians :

$ sudo purge-old-kernels –keep 3

That's all folks enjoy ! 🙂


Upgrade Debian Linux 9 to 10 Stretch to Buster and Disable graphical service load boot on Debian 10 Linux / Debian Buster is out

Tuesday, July 9th, 2019

Reading Time: 5minutes


I've just took a time to upgrade my Debian 9 Stretch Linux to Debian Buster on my old school Laptop (that turned 11 years old) Lenovo Thinkpad R61 . The upgrade went more or less without severe issues except few things.

The overall procedure followed is described n a few websites out there already and comes up to;


0. Set the proper repository location in /etc/apt/sources.list

Before update the sources.list used are:

deb [arch=amd64,i386] buster main contrib non-free
deb-src [arch=amd64,i386] buster main contrib non-free


deb [arch=amd64,i386] buster/updates main contrib non-free
deb-src [arch=amd64,i386] buster/updates main contrib non-free

deb [arch=amd64,i386] buster-updates main contrib non-free
deb-src [arch=amd64,i386] buster-updates main contrib non-free

deb buster-backports main

For people that had stretch defined in /etc/apt/sources.list you should change them to buster or stable, easiest and quickest way to omit editting with vim / nano etc. is run as root or via sudo:

sed -i 's/stretch/buster/g' /etc/apt/sources.list
sed -i 's/stretch/buster/g' /etc/apt/sources.list.d/*.list

The minimum of config in sources.list afterthe modificationshould be

deb buster main
deb buster-updates main
deb buster/updates main

Or if you want to always be with latest stable packages (which is my practice for notebooks):

deb stable main
deb stable-updates main
deb stable/updates main


1. Getting list of hold packages if such exist and unholding them, e.g.


apt-mark showhold

Same could also be done via dpkg

dpkg –get-selections | grep hold

To unhold a package if such is found:

echo "package_name install"|sudo dpkg –set-selections

For those who don't know what hold package is this is usually package you want to keep at certain version all the time even though after running apt-get upgrade to get the latest package versions.

2. Use df -h and assure you have at least 5 – 10 GB free space on root directory / before proceed

df -h /

3. Update packages list to set new set repos as default

apt update


4. apt upgrade

apt upgrade

Here some 10 – 15 times you have to confirm what you want to do with configuration that has changed if you're unsure about the config (and it is not critical service) you're aware as such as Apache / MySQL / SMTP etc. it is best to install the latest maintainer version.

Hopefully here you will not get fatal errors that will interrupt it.

P.S. It is best to run apt-update either in VTTY (Virtual console session) with screen or tmux or via a physical tty (if this is not a remote server) as during the updates your GUI access to the gnome-terminal or konsole / xterm whatever console used might get cut. Thus it is best to do it with command:

screen apt upgrade


5. Run dist-upgrade to finalize the upgrade from Stertch to Buster


Once all is completed of the new installed packages, you will need to finally do, once again it is best to run via screen, if you don't have installed screen install it:


if [ $(which screen) ]; then echo 'Installed'; else apt-get install –yes screen ; fi

screen apt dist-upgrade

Here once again you should set whether old configuration to some e services has to stay or the new Debian maintainer package shipped one will overwrite the old and locally modified (due to some reason), here do wisely whatever you will otherwise some configured services might not boot as expected on next boot.


6. What if you get packages failed on update

If you get a certain package failed to configure after installed due to some reason, if it is a systemd service use:


journalctl -xe |head -n 50

or fully observer output of journalctl -xe and decide on yourself.

In most cases

dpkg-reconfigure failed-package-name

should do the trick or at least give you more hints on how to solve it.


Also if a package seems to be in inconsistent or broken state after upgrade  and simple dpkg-reconfigure doesn't help, a good command
that can help you is


dpkg-reconfigure -f package_name


or you can try to workaround a failed package setup with:

dpkg –configure -a

If dpkg-reconfigure doesn't help either as I experienced in prior of Debian from Debian 6 -> 7 an Debian 7 ->8 updates on some Computers, then a very useful thing to try is:

apt-get update –fix-missing 

apt-get install -f

At certain cases the only work around to be able to complete the package upgrade is to to remove the package with apt remove but due to config errors even that is not possible to work around this as final resort run:

dpkg –remove –force-remove-reinstreq


7. Clean up ununeeded packages


Some packages are left over due to package dependencies from Stretch and not needed in buster anymore to remove them.

apt autoremove


8. Reboot system once all upgrade is over




9. Verify your just upgraded Debian is in a good state


root@noah:~# uname -a;
Linux noah 4.19.0-5-rt-amd64 #1 SMP PREEMPT RT Debian 4.19.37-5 (2019-06-19) x86_64 GNU/Linux


root@noah:~# cat /etc/
Debian GNU/Linux 10


root@noah:~# lsb_release -a
No LSB modules are available.
Distributor ID:    Debian
Description:    Debian GNU/Linux 10 (buster)
Release:    10
Codename:    buster


root@noah:~# hostnamectl
   Static hostname: noah
         Icon name: computer-laptop
           Chassis: laptop
        Machine ID: 4759d9c2f20265938692146351a07929
           Boot ID: 256eb64ffa5e413b8f959f7ef43d919f
  Operating System: Debian GNU/Linux 10 (buster)
            Kernel: Linux 4.19.0-5-rt-amd64
      Architecture: x86-64


10. Remove annoying picture short animation with debian logo looping



By default Debian 10 boots up with annoying screen hiding all the status of loaded services state .e.g. you cannot see the services that shows in [ FAILED ] state and  which do show as [ OK ] to revert back the old behavior I'm used to for historical reasons and as it shows a lot of good Boot time debugging info, in previous Debian distributions this was possible  by setting the right configuration options in /etc/default/grub

which so far in my config was like so

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash scsi_mod.use_blk_mq=y dm_mod.use_blk_mq=y zswap.enabled=1 text"

Note that zswap.enabled=1 passed option is because my notebook is pretty old machine from 2008 with 4GB of memory and zswapdoes accelerate performance when working with swap – especially helpful on Older PCs for more you can read more about zswap on ArchLinux wiki
After modifying this configuration to load the new config into grub the cmd is:


As this was not working and tried number of reboots finally I found that annoying animated gif like picture shown up is caused by plymouth below is excerpts from Plymouth's manual page:

       "The plymouth sends commands to a running plymouthd. This is used during the boot process to control the display of the graphical boot splash."

Plymouth has a set of themes one can set:


# plymouth-set-default-theme -l


I tried to change that theme to make the boot process as text boot as I'm used to historically with cmd:

update-alternatives –config text.plymouth

As after reboot I hoped the PC will start booting in text but this does not happened so the final fix to turn back to textmode service boot was to completely remove plymouth

apt-get remove –yes plymouth

Migrate VMWare Linux Virtual Machine to Virtualbox – Convert VMware .VMX to .OVF (Open Virtual Format)

Monday, June 2nd, 2014

Reading Time: 4minutes


VMWare Virtual Machines are usually stored in OVA Format  which is bundle of OVF(Open Virtualization Format) and in multiple *.VMDK files.
Though other Virtual Machines are supposed to also support these "open virtualization format", different VM vendors implement and support it differently, therefore though in theory VirtualBox and QEMU are said to support OVA Format. Attempts to import such usually will fail. In this little article I will explain how VMWare stored (exported) VirtualMachine machine can be succesfully imported to VirtualBox.

1. Locate where is Virtualbox .vmx files from Window search or via dir command

I'm a console guy, so I prefer looking for VMWare's .vmx from command line:

C:\Users\GGEORGI7> cd c:\ C:\> dir /s *.vmx


Volume in drive C is PC COE
Volume Serial Number is XXXX-XXXX

Directory of C:\Users\ggeorgi7\Documents\Virtual Machines\Debian 7

06/02/14 11:06 AM 2,687 Debian 7.vmx
05/28/14 15:44 PM 370 Debian 7.vmxf
2 File(s) 3,057 bytes

2. Switch to wherever the VMWare virtualmachine .vmx file is located


C:\> cd \Users\ggeorgi7\Documents\Virtual Machines\Debian 7

N.B. !Make sure the VMWare Virtualmachine is Shutdown (if it is Suspended converted file will not be properly implemented inside VirtualBox!). Whether the migrated virtualhost is suspended, launch VMWare, restore its state and Shut it down properly before starting migration with ovftool.

3. Remove Vmware-tools, Reset Display settings and Input D (before exporting to OVF) in VMWare

a) Remove vmware-tools

Vmware-tools kernel modules and stuff compiled specific for VMWare are no longer needed and might pose issues, thus it is always a good idea if previously installed in VMWare to wipe them out with cmd:

b) Reset Display Device and Input Devices

Inside VMWare virtual machine Linux host, before shutting it down run:

mv /etc/X11/xorg.conf /etc/X11/xorg.conf.vmware

c) Remove Incomptable devices

To prevent issues with sound – its necessary to remove VMWare device created for soundcard, in order to let VirtualBox create its soundcard device on 1st boot after migration. To do so click on Virtual Machine and from context menu click Settings then in  Hardware tab select Sound Card and Remove:

Settings-> Hardware -> Sound Card (Click Remove)


4. Make a Clone (Backup) of Virtual Machine

Its always a good idea to create backup of VMWare VM to be migrated just in case something goes wrong during migration, so you have a way to step back to the already working one. Once files are copied it might be a good idea to use use some archiver like PeaZip or 7-Zip to save some disk space.

mkdir SomeFolder
copy Path_To_Virtual_Machine Folder_for_Backup_Virtual_Machine


In my case this was



mkdir \Temp\VMWare-machine-backup
C:\>copy "C:\Users\ggeorgi7\Documents\Virtual Machines\Debian 7"\ c:\Temp\VM

Restoring later VMWare VirtualMachines in case of some failure is done by simply copying backuped files to VMWare Working Directory folder

In case if Wondering

Where is stored VMWare Virtual Machines?


Check in:

VM -> Settings -> Options


5. Use VMWare ovftool.exe to convert .VMX to Open Virtualization Format (.OVF)


Though export from .VMX to .OVF it can be also done from VMWare GUI from:

File -> Export to OVF

Anyways I think it is better to do it via OVFTool console tool:

The most common location for  VMWare Workstation is:

C:\Program Files (x86)\Vmware\Vmware Workstation\OVFTool

For VMware Player it is:

C:\Program Files (x86)\Vmware\Vmware Player\OVFTool

Very important thing to mention here is you have to be cautious, Never to run together VMWare and VirtualBox.
!! Before proceeding to next OVTool .vmx to .ovf migration Shutdown the VirtualMachine and as a best practice close VMware completely.

cd Location-directory-ofOVFTool
ovftool.exe Path-folder-to_VMVM_file.vmx Path-folder_to_VM_exportVM_file_export.ovf

C:\> cd "\Program Files (x86)\VMware\VMware Workstation"\OVFTool
C:\Program Files (x86)\VMware\VMware Workstation\OVFTool>ovftool.exe "\Users\ggeorgi7\Documents\Virtual Machines\Debian 7\Debian 7.vmx" C:\Users\ggeorg i7\vmware-debian-export.ovf



Convertion will take about 30 minutes on a normal computer hardware lets say (Dual Core PC 2Ghz with 4 Gb of RAM).
If you get a “failed to open disk” error during convertion, its likely that the virtual machine is still running or wasn’t shut down properly – boot the virtual machine and perform a shut down.

6. Launch VirtualBox, Install Guest Additions to enable Copy / Paste and USB support in Virtual Machine

After the process completes, you can boot the virtual machine. If you haven't earlier uninstalled vmware-tools  uninstall VMware Tools, and install VirtualBox’s Guest Additions (in order to allow Copy / Paste between VirtualBox and guess OS).

7. Launch VirtualBox and Import exported .OVF

Once Virtual Machine is exported, to import it into VirtualBox, launch VirtualBox and choose:

File -> Import Appliance

virtualbox-import-vmware-old-virtual-machine-to-new-linux import vmware appliance

virtualbox-import-vmware-previously-installed-virtual-machine-linux import appliance virtualbox

How to delete “Temporary Internet Files”/Content.IE5 with DEL and RD commands on Windows 7 / 8 folder contents – Clean Up Temporary files and folders to speed up and free disk space

Tuesday, February 3rd, 2015

Reading Time: 5minutes

've been called urgently today by miss Jenia Pencheva who is the president of Christian Air Ticket Agency GoodFaithAir, her personal computer caused her quite a lot of headache, I've previously fixed it once and she was happy with that thus when she experienced problems she give me a call for remote IT support :).

She explahed her PC was unable to boot normally and in order to have some Windows she ended in Safe-Mode with Networkingstate. This problems caused her business losses as during PC in Safe mode the screen resolution even though with networking and she couldn't use the flight ticket ordering systems  to purchase her customers new tickets.  I've earlier installed TeamViewr on her PC so after Logging on the PC, I've immediately realized the Hard Disk was almost full (less than 1Giga free on C: Drive – where Windows install lived)

After a thorough investigation on which directory is occupying most of disk space (110GB) with a nice program called SpaceSniffer which is perfect for finding lost space on your hard disks, I've found System for ticket reservation Amadeus CRS (Computer Reservation System) was causing the disk full-full troubles.


I've found troubling directory  was:

C:UsersgoodfaithairAppDataLocalMicrosoftWindowsTemporary Internet FilesContent.IE5

To solve it I first tried to Clean up Internet Explorer Cache (I've checked ticks Temporary Internet files, Cookies, History, Download History, Form Data, InPrivate Filtering Data).


Then I used Microsoft Windows embedded clean manager (cleanmgr.exe) to run disk clean up, however Desk Clean Up managed to clear up only about 1Giga and on the computer HDD which is 150Gb still on Windows installation drive C: only 1.5GB were free.
Besides that the system was having a second trouble as there were some failed updates (Computer was not shutdown properly but shutdown during Windows Update) and this was making the machine to enter Safe-Mode, I was fixing the system over TeamViewer session so after restart I had no way to see if Windows boots Normal or Safe-Mode after restart, thus to find out whether Windows was in Safe-Mode after another restart I've used below PowerShell one-liner script:


PS C:> gwmi win32_computersystem | select BootupState

Fail-safe with network boot

Note that possible return results from above command are:

Normal boot
Fail-safe boot
Fail-safe with network boot

I've been struggling for a while (had to restart it multiple times) until finally I managed to make it boot in normal mode. Because PC was failing to apply some Windows Update, thus dropping by in Safe-Mode each time. To solve that I had to go and Delete two of the last Applied updates (KB2979xxxx files).

Control Panel ->  Program and Features -> View Installed Updates

I've restarted and since I couldn't see the screen on Windows boot-time, I don't know what really happened but the PC booted again in Safe-Mode, and I thought the classical way to fix PC booting in Safe-Mode with SFC command will help:

C:> sfc /scannow

but for my surprise this helped not as the system continuously booted in Safe-Mode, to fix the Windows PC always booting to Safe-Mode, I had to change it running msconfig and untickingSafe Mode field

C:> msconfig


Then I tried to delete Temporary Internet Files with below DEL cmd line

C:>del "C:UsersMyNameAppDataLocalMicrosoftWindowsTemporary Internet Files*.*"

To finally succeeding in manually deletehuge Temporary Internet FilesContent.IE5 folder, I had to use good old RD (Remove Directory) command.


C:> RD "C:UsersusernameAppDataLocalMicrosoftWindowsTemporary Internet FilesContent.IE5" /Q /S

I used also following dels command to delete other common locations where Windows stores temporary files

For those who like to batch DeletingTemporary Internet Files and most common Temp locations to be cleaned on Windows boot I recommend you schedule a start of (clean-temporary-internet-files-content_ie5_folder.bat) on every PC boot.

To Clean-up other common Temporary file locations that could take you disk space the command line way run in new Administarator privileged command prompt:

cleanmgr /sageset:99
del /F /S /Q "%systemroot%temp*.*"
del /F /S /Q "%systemroot%Prefetch*.*"
del /F /S /Q "C:Documents and SettingsDefault UserLocal SettingsTemporary Internet FilesContent.IE5*.*"
del /F /S /Q "C:Documents and SettingsDefault UserLocal SettingsTemp*.*"
del /F /S /Q "C:Documents and SettingsDefault UserLocal SettingsHistory*.*"
del /F /S /Q "C:Documents and Settings%UserName%Local SettingsTemporary Internet FilesContent.IE5*.*"
del /F /S /Q "C:Documents and Settings%UserName%Local SettingsTemp*.*"
del /F /S /Q "C:Documents and Settings%UserName%Local SettingsHistory*.*"
del /F /S /Q "C:Documents and Settings%UserName%Local SettingsApplication DataTemp*.*"
del /F /S /Q "C:Documents and Settings%UserName%Local SettingsApplication DataTemporary Internet FilesContent.IE5
del /F /S /Q "C:AppDataLocalMicrosoftWindowsHistory*. *"
del /F /S /Q "C:AppDataLocalMicrosoftWindowsTemporary Internet FilesContent.IE5*.*"
del /F /S /Q "C:AppDataLocalMicrosoftWindowsTemporary Internet FilesLowContent.IE5*.*"
del /F /S /Q "C:AppDataLocalMicrosoftWindowsTemporary Internet FilesTemporary Internet FilesContent.IE5*.*"
del /F /S /Q "C:AppDataLocalMicrosoftWindowsTemporary Internet FilesTemporary Internet FilesLowContent.IE5*.*"
del /F /S /Q "C:Users%UserName%AppDataLocalTemp*.*"
del /F /S /Q "C:Temp*.*"
del /F /S /Q "C:Users%UserName%AppDataLocalMicrosoftW indo wsTemporary Internet FilesLowContent.IE5*.*
del /F /S /Q "C:Users%UserName%AppDataLocalMicrosoftW indo wsHistory*.*
::Rem: No need to duplicate the following section for each registered User
del /F /S /Q "%homepath%Cookies*.*"
del /F /S /Q "%homepath%recent*.*"
del /F /S /Q "%homepath%Local Settingscookies*.*"
del /F /S /Q "%homepath%Local SettingsHistory*.*"
del /F /S /Q "%homepath%Local SettingsTemp*.*"
del /F /S /Q "%homepath%Local SettingsTemporary Internet FilesContent.IE5*.*"
cleanmgr /sagerun:99

Note that in some cases running above commands might left you loose some sensitive data and in case where Internet is slow cleaning temporary files, might have impact on surfing also you will loose your history so be sure you know what you're doing as you might loose sensitive data.

Finally I've run MalwareBytes to clean up the PC slowness caused by Spyware and other left Malware I've run MalwareBytes, RogueKiller, AdwCleaner, RKill, TDSSKiller in order and I found and removed few Malwares as well.

That's all, hope you learned something new. Enjoy!

How to disable IPv6 on Debian / Ubuntu / CentOS and RHEL Linux

Friday, December 9th, 2011

Reading Time: 1minute
I have few servers, which have automatically enabled IPv6 protocols (IPv6 gets automatically enabled on Debian), as well as on most latest Linux distribituions nowdays.

Disabling IPv6 network protocol on Linux if not used has 2 reasons:

1. Security (It’s well known security practice to disable anything not used on a server)
Besides that IPv6 has been known for few criticil security vulnerabilities, which has historically affected the Linux kernel.
2. Performance (Sometimes disabling IPv6 could have positive impact on IPv4 especially on heavy traffic network servers).
I’ve red people claiming disabling IPv6 improves the DNS performance, however since this is not rumors and did not check it personally I cannot positively confirm this.

Disabling IPv6 on all GNU / Linuces can be achieved by changing the kernel sysctl settings net.ipv6.conf.all.disable_ipv6 by default net.ipv6.conf.all.disable_ipv6 equals 1 which means IPv6 is enabled, hence to disable IPv6 I issued:

server:~# sysctl net.ipv6.conf.all.disable_ipv6=0

To set it permanently on system boot I put the setting also in /etc/sysctl.conf :

server:~# echo 'net.ipv6.conf.all.disable = 1 >> /etc/sysctl.conf

The aforedescribed methods should be working on most Linux kernels version > 2.6.27 in that number it should work 100% on recent versions of Fedora, CentOS, Debian and Ubuntu.

To disable IPv6 protocol on Debian Lenny its necessery to blackist the ipv6 module in /etc/modprobe.d/blacklist by issuing:

echo 'blacklist ipv6' >> /etc/modprobe.d/blacklist

On Fedora / CentOS there is a another universal “Redhat” way disable IPv6.

On them disabling IPv6 is done by editting /etc/sysconfig/network and adding:


I would be happy to hear how people achieved disabling the IPv6, since on earlier and (various by distro) Linuxes the way to disable the IPv6 is probably different.

Alto to stop Iptables IPV6 on CentOS / Fedora and RHEL issue:

# service ip6tables stop

# service ip6tables off

How to store username and password permanently in Weblogic Application server –

Tuesday, January 14th, 2014

Reading Time: < 1minute

oracle weblogic proprietary webserver logo make server user and password permanent

I'm following a training intensive 5 days course for Oracle WebLogic. Some of exercises included stopping / starting Weblogic App server for security reasons Weblogic is designed to always propmpt for password. I remember similar behavior in Apache configured to use SSL certificate.
Whether a new Weblogic server is configured and a frequent restart of server is needed having to write the password each and everyime is mostly annoying. Thanksfully there is a file called in which username / password can be hardcoded and later red on Weblogic start. As contains security credentials its very important to keep the file as secured as possible. files can be set-up for each different configured separate Weblogic server instance.

For my training sessiion is in locations:



cat /home/oracle/wls11g_advadm/work/domains/MedRecDomain/servers/MedRecSvr2/security/

Depending on how Oracle Weblogic is configured its possible values in (username / password) to be encrypted after first server boot-up.

Raspberry Pi – Cheap portable credit-card sized single board Linux computer box

Thursday, November 7th, 2013

Reading Time: 3minutes

RaspberryPi tiny-computer running Linux and free software Logo

Not of a the latest thing out there but I believe a must know for every geek is existence of Raspberry Pimini computer Linux board. It is a geek credit-card sized mini PC on extremely cheap price between 25$ and 35$ bucks (e.g. Raspberry Pi model A and Raspberry Pi Model B).

Raspberry Pi hardware you get for this ultra low price is as follows:

  • Broadcom BCM2835 system on chip
  • ARM Mobile processor model ARM1176JZF running at 700 Mhz(overlocking up to 1Ghz is possible – overclocked RP is called Turbo 🙂 )!
  • VideoCore IV GPU with 512 MBytes of ram
  • No Build hard disk or solid-state drive but instead designed to use SD-Card as a Storage
  • two video outputs
  • composite RCA and an HDMI port
  • 3.5mm audio output
  • 2 or 1SD/MMC/SDIO card slot (depending on device model A or model B)
  • Micro USB adapter power charger 500mA  (2.5 watts) – Model and 700mA (3.5 watts)

Raspberry PI mini computer hardware running Linux explained picture

The idea of whole device is to make cheap affordable device for pupils and people from third countries who can't afford to pay big money for a full-featured computer. Achievement is unique all you need to Raspberry Pi credit card sized device is external keyboard a mouse, SD-card and a monitor, this makes a 700Mhz featured almost fully functional computer for less than lets say 80$ whether used with a second hand monitor / mouse and kbd :). A fully functional computer or full functional thin client for as less as 80$ yes that's what RaspberryPi is!

It is recommendable that SD-Card storage on which it is installed is at least 4GB as this is part of its minimum requirement, however it is best if you can get an SD-Card of 32GByteswhether you plan to use its whole graphic functionalities.

Raspberry Pi Hardware is not too powerful to run a version of Windows as well as there is no free version of MS-Windows for ARM Processor, so basicly device is planned to run free software OSes GNU / Linux. 5 operating systems are working fine with the mini-board device as time of writting;

  • Raspbian – Debian "Wheezy" Linux port
  • Pidora – Fedora mixed version ported to run on Raspberry Pi
  • Risk OS port
  • Arch Linux port for ARM devices
  • Slackware Arm
    FreeBSD / NetBSD
  • QtonPi

Recommended and probably best distro port is for Debian Squeeze

To boot an OS into raspberry PI dowbnload respective image from

– Use application for copying and extracting image to SD-Card like Win32 Disk Imager – whether on Windows platform

Win32DiskImager burning raspberry PI mini Linux card board computer box image

– Or from Linux format SD-Card with gparted (N!B! format disk to be in FAT32 filesystem), extrat files and copy them to SD-CARD.

Once Raspberry Pi loads up it will drop you into Linux console, so further configuration will have to be done manually with invoking plenty of apt-get commands (which I will not talk about here as there are plenty of manuals already) – you will have to manually install your Desktop … Default shipped Web browser in Debian is Midori and due to lack of ported version of flash player for ARM streaming video websites like / does not work in browser. There is a Google Chrome for Raspberry Pi port but just like with Midori heavy object loaded websites works very slow and thus not very suitable for multimedia.

raspberry pi cheaest portable linux powered computer sized of a credit card

Raspberry Pi device is very suitable for ThinClient use there is a special separate project – Raspberry ThinClient Project – using which a hobbyist can save 400$ for buying proprietary ThinClient.

RaspberryPI linux as a free software hardware thinclient picture


How to disable PC Speaker on FreeBSD / Mute PC-Speaker on BSD kernels

Wednesday, May 16th, 2012

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old school personal computer pc speaker / freebsd disable Pc-Speaker picture

After finding out How PC Speaker is muted on Linux , I've decided to also disable the annoying beeps on BSD. This is in tandem with the minimalistic philosophy I try to apply to every server I manage.

Also on BSD Desktop machines it is quite annoying especially if csh (C Shell) is used, everytime you press TAB you get the beep sound. On BSD beep sound produced on tab completion is louder than in Linux and that makes it even more annoying …

Disabling pc-speaker beeps on BSDs is done via a sysctl kernel variable:

freebsd# sysctl hw.syscons.bell=0
hw.syscons.bell: 0 -> 0

To further permanently disable on system boot add hw.syscons.bell=0 to /etc/sysctl.conf, e.g.:

freebsd# echo 'hw.syscons.bell=0' >> /etc/sysctl.conf


Well that's it no more mind drilling beeps :)


How to install GNOME server on Ubuntu 10.04.2 LTS Lucid

Wednesday, April 20th, 2011

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After some upgrades of Ubuntu from 9.10 to Ubuntu 10.04.2, I faced problems during apt-get upgrade && apt-get dist-upgrade

I had to fix it up with apt-get upgrade -f , however the “fix” which was targetting a fix up to the apt-get dist-upgrade removed about 260 packages, among which were the grub boot loader , xorg-server and even gnome

As in order to fix the package mishap the apt-get update -f was my only possible solution I went by and confirmed that I would like to wipe out all the packages.

Logically afterwards it was required that I install my missing xorg-server and gnome in order to make the Ubuntu desktop work again.

Here is how:

ubuntu:~# apt-get update && apt-get xorg-server ubuntu-desktop

The ubuntu-desktop is a meta package which installs the GNOME environment.