Single quote in awk

awk '{ print ",", foo$1foo }' foo="'"  file

Delimiter in awk -F, and the last column $NF
cat /etc/passwd | awk -F: ‘{print $5}’ | awk -F, ‘{print $NF}’

Field separator

awk '{ FS = "\t"; print $3 }' file

Line number: NR

Sum the number in a column, say column 1

awk '{ sum+=$1 } END {print sum}' file


Here are the three steps that I run VNC at my home.

1. Your Linux system might already have the software installed (type “which vncpasswd” to tell). If not, download the software from, and install it on your Linux and windows, respectively.

2. Launch from the server side (Linux)
$ vncpasswd
$ vncserver

3. Lanuch from the client (windows)
when prompted the server name, type linux_host_name:1, where linux_host_name is your linux box name and 1 is the port number for the vncserver, which could be a different port number sometime (you can tell it from the “vncserver” output at the previous step).

4. set kde

$ vi .vnc/xstartup

twm &
startkde &


1) make sure ssh and rsync are installed on both computers

2) at the visitor machine’s shell window, type the following command
$ cd /root/.ssh
$ ssh-keygen -t dsa -b 1024 -f visitor_machine_key

enter a BLANK passphrase

3) generate a file called “config” in the visitor machine under /root/.ssh/ with options like these
Host remote_host_machine
User root
Compression yes
Protocol 2
RSAAuthentication yes
StrictHostKeyChecking no
ForwardAgent yes
ForwardX11 yes
IdentityFile /root/.ssh/visitor_machine_key

4) Copy the /root/.ssh/ file and paste the file in or
at the end of the remote host machine’s file /root/.ssh/authorized_keys2