Perl script to quiz you for ARRL Ham radio exam

I've been studying for the Technician class amateur radio license. The ARRL sells a book that includes a CD with some nice software for practicing tests. However, if you don't have the book and/or CD, you might want to practice the test questions anyway. So I wrote a perl script that reads the text version of the question pool ( 2010 version or 2014 version), then asks you questions from it. example run:

# study.pl ~/Downloads/question_pool.txt

enter question # (blank for random question) or Ctrl-C to exit :

T6B07
What does the abbreviation "LED" stand for?
A. Low Emission Diode
B. Light Emitting Diode
C. Liquid Emission Detector
D. Long Echo Delay


answer? A
*** WRONG!      correct answer is (B)

enter question # (blank for random question) or Ctrl-C to exit :

T7A07
If figure T5 represents a transceiver in which block 1 is the transmitter portion and block 3 is the receiver portion, what is the function of block 2?
A. A balanced modulator
B. A transmit-receive switch
C. A power amplifier
D. A high-pass filter


answer? b
CORRECT!

Download the script

Automating the VMware vSphere Perl SDK install with expect:

I couldn't find any other postings on the net about this, so here's my solution for automating the installation for the VMware vSphere Perl SDK on RHEL6 (this assumes you already have all the prerequisites installed.).  It probably works on any Linux OS but I only tested it on RHEL6.4.

Save this expect script (requires expect to be installed, duh!) in the same directory as the extracted tarball for the SDK (probably vmware-vsphere-cli-distrib/):

#!/usr/bin/expect

set timeout 120

spawn "./vmware-install.pl"

expect "Press enter to display " { send "\r" }
expect "vSphere Software Development Kit License Agreement" { send "q" }
expect "Do you accept" { send "yes\r" }
expect "Do you want to install precompiled Perl modules for RHEL" { send "\r" }
expect "In which directory do you want to install the executable files" { send "\r" }
# Wait for installation to finish
expect EOF

This accepts the defaults ("yes" to installing precompiled perl modules, "/usr/bin" for the installation directory) If you don't like that, edit the script!

SSH tunnel to multiple vSphere/ESXi hosts

An SSH tunnel to a single host is easy; reference: http://www.virtuallifestyle.nl/2010/03/tunneling-a-vsphere-client-connection-over-ssh/

However, if you want to open the vSphere client multiple times for simultaneous connections to multiple ESXi/vCenter hosts, then you have to get a little creative. Basically you follow the same instructions as above, except you don't need to edit the hosts file. Just use a single address in the loopback network (127.0.0.2 - 127.255.255.254 ) for each remote ESXi host.  e.g.:

ESXi host	Tunnel Source	Tunnel Destination
host1	127.0.0.2:443	esxhost1:443
host1	127.0.0.2:902	esxhost1:902
host1	127.0.0.2:903	esxhost1:903
host2	127.0.0.3:443	esxhost2:443
host2	127.0.0.3:902	esxhost2:902
host2	127.0.0.3:903	esxhost2:903

Then simply connect vSphere client to one of the loopback addresses you used.  In the example above, to connect to esxhost1, you connect vSphere Client to 127.0.0.2.  For esxhost2, 127.0.0.3.

You should be able to make up to ~16 million tunnels this way!

See this entry if you need to open a console on one of your guests

NOTE: When using an SSH tunnel, the vSphere Client will not show the "Hardware" tab for your hosts.