ThinkFirst, BlinkSecond

On the server, download apt-cacher-ng:

sudo apt-get install apt-cacher-ng

edit /etc/apt-cacher-ng/acng.conf and change the BindAddress to:

0.0.0.0

Now restart the service:

/etc/init.d/apt-cacher-ng restart

On the clients:

create /etc/apt/apt.conf.d/03proxy and add:

Acquire::http { Proxy "http://serveriP:3142"; };

now run:

sudo apt-get update

Then browse to:

http://serverIP:3142/acng-report.html

You should see something like:

Here’s how to automate that response:

apt-get -o DPkg::options="--force-confdef" -o DPkg::options::="--force-confold" dist-upgrade

or add the following to /etc/apt/apt.conf.d/ (could be any filename)

DKpg::Options { "--force-confdef"; "--force-confold"; }

Here’s the error:

dpkg: warning: overriding problem because –force enabled:
Package is in a very bad inconsistent state – you should
reinstall it before attempting a removal.
(Reading database … 50584 files and directories currently installed.)
Removing mcollective-plugins-facts-facter …
sed: -e expression #1, char 52: unknown option to `s’
dpkg: error processing mcollective-plugins-facts-facter (–remove):
subprocess installed post-removal script returned error exit status 1
Errors were encountered while processing:
mcollective-plugins-facts-facter

here’s the fix that worked for me:

 cd /var/lib/dpkg/info 

 rm -rf mcollective-plugins-facts-facter.* 

 dpkg --remove --force-remove-reinstreq mcollective-plugins-facts-facter 

That’s it!

 pdsh -w ptaylor@10.40.160.54 hostname 

* this command tries to connect to 10.40.160.54 and get the hostname

This would fail with:

 pdsh@ubuntu: 10.40.160.54: rcmd: socket: Permission denied 

Not very helpful.

Turns out it is looking for a file in /etc/pdsh:

 /etc/pdsh/rcmd_default 

I found this out by looking at /usr/bin/pdsh (bash script).

Once you’ve created the rcmd_dafault file, just add “ssh” to it.

 echo "ssh" | sudo tee -a /etc/pdsh/rcmd_default 

Now if you try running pdsh again, it should work just fine:

% pdsh -w ptaylor@10.40.160.54 hostname
10.40.160.54: ubuntuserver2

I’ve seen this multiple times and I still keep forgetting to make the necessary changes prior to running:

 sudo apt-get update 

Here’s a fix I found that works for me (I’m using 12.04LTS).

 echo "Acquire::http::Pipeline-Depth "0";" | sudo tee -a /etc/apt/apt.conf.d/90localsettings 

The bug is known at:

 https://code.google.com/p/chromium/issues/detail?id=93409 

check all databases

 mysqlcheck -c -u root -p --all-databases 

check specific database table

 mysqlcheck -c <dbname> <tablename> -u root -p 

Repairing table

 mysqlcheck -r <dbname> <tablename> -u root -p 

Check, optimize and repair all the tables

 mysqlcheck -uroot -p --auto-repair -c -o --all-databases 

Here’s the error:

*** REMOTE GEMS ***
/home/ptaylor/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’: cannot load such file — zlib (LoadError)

Here’s the fix:

 rvm pkg install zlib 

 rvm remove 1.9.3 

 rvm install 1.9.3 

# Let's say I have this array
a = %w[apple apple apple ubuntu ubuntu ubuntu ubuntu debian redhat]

def main(obj)
  # Set Hash to 0 so it counts
  counter = Hash.new(0)

  # iterate over the list
  obj.each { |x| counter[x] += 1 }

  # return the Hash
  return counter
end

# now run counters
puts main(a)

So now when you run the code, you’ll get an output like this:

String.methods.grep(/^wr/)

or

String.methods.grep /^wr/

Everyone has their format.

So with the above, you can then say well since there’s no method that begins with “wr”, I can add one if I wanted.

class String
  def write_size
    self.size
  end
end

puts 'Hello'.write_size

 export TERM="xterm-256color" 

You might need ncurses-term.

 sudo apt-get install ncurses-term 

You can also check that you have 256 colors available by running:

 tput colors