Recompile virtual box kernel modules after kernel update

If Virtualbox or guest aditions are not starting ater a kernel update, just recompile the kernel modules:


o On a Virtualbox server

    /etc/init.d/vboxdrv setup

o On a Virtualbox guest

    /etc/init.d/vboxadd setup

Grub2: Set default boot option

o Get the string of the menu entry you desire to be default

  fgrep menuentry /boot/grub/grub.cfg
  ...
  menuentry "Some OS" {
  ...
 
o Add menu entry to /etc/default/grub
  
  vi /etc/default/grub 
  GRUB_DEFAULT="Some OS"

o Update grub

  update-grub

Enhance Adobe flash player performance in Linux

These settings will slightly improve the performance of the adobe flash
plugin:

o Customize /etc/X11/xorg.conf

     

  Section "Extensions"
    # for 3D, alpha desktop effects
    Option "Composite" "Enable"
  EndSection

  Section "DRI"
    # helps flash performance
    Mode 0666
  EndSection

o Override GPU Validation

   - Sytem wide

    sudo mkdir /etc/adobe
    echo "OverrideGPUValidation=true" > /etc/adobe/mms.cfg

- Or user wide

    echo OverrideGPUValidation=true > ~/.adobe/mms.cfg

Get SOAP communication using tcpdump

Assume you have a Tomcat running on localhost on port 8080 and want see the content of the SOAP messages of the communication:

tcpdump -i lo0 -A -s 1024 -l 'dst host localhost and port 8080'

Drop Oracle Database

Since 10g, It is possible to drop a database in Oracle 10g with the new SQL statement drop database.

The command gets rid of datafiles online redo log files, controlfiles and spfile:

sqlplus / as sysdba

shutdown abort;

startup mount exclusive restrict;

drop database;

exit