MySQL Gem Installation Under RedHat Enterprise Linux

Posted by Tres Mon, 03 Nov 2008 09:34:00 GMT

Installing the mysql Gem under RHEL/CentOS requires you to specify where MySQL is installed. Just point Gem to the mysql-config bin & you’re good to go:

gem install mysql -- --with-mysql-config=/usr/bin/mysql_config

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gem update One-Liner To Update Everything

Posted by Tres Wed, 14 May 2008 01:44:00 GMT

Here’s an easy one-liner to get ruby gem and all installed gems up to the latest available version:

gem update -y --system --include-dependencies && gem update -y --include-dependencies

Newer versions of gem include dependency installs and are not interactive, so you don’t need to use the flags outlined above. Just use:

gem update --system && gem update

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Ruby Script For Checking Memory Usage in domU From dom0 in Xen

Posted by Tres Sun, 20 Apr 2008 00:36:00 GMT

Here’s a little ruby hackery to do convert the output we got here into something like this:

MB total: 2432.0
MB used: 479.6953125
MB free: 1952.3046875


#!/usr/bin/env ruby

require 'optparse'

options = {}
outprint = {}
ot = String
opts = OptionParser.new do |opts|
        opts.on("-p X", "--path X", String, "path to partition for host") do |path|
                options[:path] = path
        end
end

opts.parse!(ARGV)

output = `dumpe2fs -h #{options[:path]}`
output.squeeze!(" ")
output.each do | line |
        line.grep(/Block count:/) { | total | outprint[:total_label] ,outprint[:total_data] = total.chomp.split(/\s*\:\s*/) }
        line.grep( /Free blocks:/) { | free | outprint[:free_label], outprint[:free_data] = free.chomp.split(/\s*\:\s*/) }
        line.grep(/Block size:/) { | size | outprint[:block_size_label], outprint[:block_size_data] = size.chomp.split(/\s*\:\s*/) }
        line.grep(/Reserved block count:/) { | reserved | outprint[:reserved_label], outprint[:reserved_data] = reserved.chomp.split(/\s*\:\s*/) }

end

mb_available = ( outprint[:block_size_data].to_f / 1048576 * outprint[:total_data].to_f )
mb_free = ( outprint[:block_size_data].to_f / 1048576 * outprint[:free_data].to_f )
mb_used = ( mb_available.to_f - mb_free.to_f )
puts "MB total: #{mb_available}"
puts "MB used: #{mb_used}"
puts "MB free: #{mb_free}"

The ruby script takes a single argument, the path to the device that is going to be looked at. It can be passed with either a -p or –path.

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