ssh key exchange

1. ssh-keygen -t rsa
2. ssh-copy-id -i ~/.ssh/id_rsa.pub remote-host
3. ssh remote-host 'ls -ahl ./ssh/ ' : to check the permisison of authorized_keys file.

Truncate the last letter in VI

Sometimes when you copy a text file from windows, you may have annoying characters at the end of each line. To remove then

:%s/.$//g

Disabling GSSAPIAuthentication in SSH

vi ~/.ssh/config

add

GSSAPIAuthentication no

for loop in bash scripts

The most compatible fashion across all the bash version is : 

#!/bin/bash
        for i in `seq 1 10`;
        do
                echo $i
        done 

How does XenServer map vCPUs to physical processing contexts?

Please refer to http://support.citrix.com/article/ctx117960

They enumerate physical processing contexts in a depth-first manner. So, in default, vCPU0 and vCPU1 will be in the core 0.

Subtables

\usepackage{subfig}

and within
\begin{table}
\subfloat[caption1]
{
    \begin{tabular}
    \end{tabular}
}
\hspace{0.1cm}
\subfloat[caption2]
{
    \begin{tabular}
    \end{tabular}
}
\end{table}
.

Additionally, for resizing sub-tables,
\scalebox{0.7} {
    \begin{tabular}
    \end{tabular}
}
.

How to find my CPU uses Hyperthreads?

cat /proc/cpuinfo | grep ht

Even if your kernel supports hyperthread and your CPU provides hyperthread, your kernel may not recognize a hyperthread as a CPU when it is not enabled in BIOS.

How to change the bullet in itemize environment

\begin{itemize}[label= xx ]

\end{itemize}

For no bullet, [label=]

Section without numbering

Use
\section*{section title}.

How to find CPU affinity of vCPUs in XenServer/XenCenter

xe vm-param-get uuid=<uuid> Param-Names=VCPUs-Params
xe vm-param-set uuid=<uuid> Param-Names=VCPUs-Params:mask=1