What you're trying to do with the jar is actually very trivial . Here's an example script. Note: You can use the builtin $^O to get the operating system and the diamond "<>" operator for user input:

#!/usr/bin/perl

use strict;
use warnings;

print
"=======================================\n";
print
"List of Databases: \n",
"Oracle = 1\n",
"DB2 = 2\n",
"Some other db = 3\n",
"=======================================\n";
print "Your system is:  $^O\n",
      "Which database do you want to use: 1, 2, or 3?\n";
my $db = <>;
if ($db == 1) {
    print "You have chosen Oracle\n";
}
elsif ($db == 2) {
    print "You have chosen DB2\n";
}
elsif ($db == 3) {
    print "You have chosen some other stuff\n";
}
else {
    print "You have not chosen a database. We can't continue.\n";
}
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