Ubuntu / Centos - Linux - Check Hyperthreading is enabled or not

Check Hyperthreading status :

Run command :
cat /proc/cpuinfo

If the number of siblings is equal to the number of cores then you have CPUs which are not hyperthreading or hyperthreading is switched off, If the number of siblings is 2x the number of cores then you have a hyperthreading CPU with hyperthreading switched on.

ssh-add - Add keys permanent

Keys are removed after reboot, Add ssh keys permanent

If you add private keys or .pem files using ssh-add and reboot your system, they are disappeared.

To add the keys permanently, here is the solution.

Suppose your key file is filename.pem and it is in Documents. In this case, Add the following command in your .bashrc file.

ssh-add /root/Documents/filename.pem 2>/dev/null
 
Now this key will be added permanently in your listing.

You can add as many keys you want.

Make xubuntu desktop classic

Remove Unity theme from xubuntu and install classic desktop


Install :
sudo apt-get install xubuntu-desktop gksu leafpad synaptic