Basic Perl Scripting
Exercise 9
To be handed in (per email to kathrin@theochem.kth.se): Thursday 8th Nov. 

In this exercise we will monitor the state of computers in a computer
cluster. We have the following data:

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enewetak.priv
     state = free

eolie.priv
     state = offline
     jobs = 0/9889.omega.biotech.kth.se, 1/10835.omega.biotech.kth.se

elba.priv
     state = offline
     
etorofu.priv
     state = job-exclusive
     jobs = 0/15420.omega.biotech.kth.se, 1/8963.omega.biotech.kth.se
--------------------------------------------------------------------

The first line gives the computer name, the state it has (free
(meaning no jobs are running), job-exclusive (2 jobs are running) or
offline (if the machine is in offline state it cannot accept new jobs,
but it might still be running old jobs. In that case we refer to the
machine as 'blocked').

You are asked to write a script that will take the above as input and
return to you the computer names that have a given state. The state
you are interested in should be given as keyword to the script. We
will use 'free' or 'blocked'. In case no keyword is specified or an
unrelated one, the program should either die or return a warning. Here
is how it should look if you try to run the script (./ means execute
this script):

./exe9.pl
  Warning: Usage: Pass free or blocked as the argument.
# (then script exits)

./exe9.pl free
   enewetak is free

./exe9.pl blocked
   eolie is offline but still has jobs 9889, 10835 running.

./exe9.pl smile
I have no idea what you want from me.
 
The script itself should use subroutines. Here is a general form of
the script:
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#! /usr/bin/perl
die "Usage: Pass free or blocked as the argument.\n" if @ARGV == 0;
if($ARGV[0] eq 'free') {
    # call a subroutine that prints all free machines;
} elsif($ARGV[0] eq 'blocked') {
    # call a subroutine that prints all machines that are offline AND
    # still runs job(s);
} else {
    die "I have no idea what you want from me.\n";
}
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