Now that we’ve secured access to our Ubuntu Karmic slice we can update it and get it ready for the rest of the server install.
In part 1 of the Ubuntu 9.10 (Karmic Koala) setup, we completed the ssh configuration along with a basic iptables setup.
Now let’s run some checks and install some personal configuration files to make life easier. Once done, we can update the install and create a solid base for the ‘meat’ of the server.
OS check
First thing is to confirm what OS we’re using. We know we should be using Ubuntu Karmic but let’s see:
cat /etc/lsb-releaseYou should get an output similar to this:
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=9.10
DISTRIB_CODENAME=karmic
DISTRIB_DESCRIPTION="Ubuntu 9.10"Good.
Using free
Memory usage should be very low at this point but let’s check using ‘free -m’ (the -m suffix displays the result in MB’s which I find easier to read):
free -mIt’s nice to know what is going on so let’s look at that output:
. total used free shared buffers cached
Mem: 254 55 199 0 2 21
-/+ buffers/cache: 30 223
Swap: 511 0 511The line to take notice of is the second one as the first line includes cached memory – in this demo slice I have 254MB memory in total with 30MB actually used, 223MB free and no swap used. Nice.
.bashrc
Normally the “ls” command doesn’t list files that start with a period. Those are usually configuration files or directories, and ls hides them so they don’t clutter up your directory view. To see all of what’s there, run:
ls -a ~The “-a” option is what tells ls to list all files, not just the non-configuration files.
You’ll see several files, but let’s focus on “.bashrc” right now. This is ultimately where your user environment (the “shell”) will look for its settings. Go ahead and open it for editing:
nano ~/.bashrcInside you’ll see a lot of shell script commands — don’t worry if you don’t understand it all. Anything we add at the end of the file will override what came before. If you want to, say, change your prompt, you don’t necessarily need to figure out what all the “if” statements in there by default are for, and which line you need to edit. You can just add your own setting at the end.
Custom prompt
With that in mind, let’s look at how to change your prompt. At its simplest, the prompt’s format is set with the “PS1″ environment variable. It consists of some numbers that determine color and some codes that act as stand-ins for variables like the current working directory and your hostname. To set your prompt to just your hostname and working directory, both in different colors, you could add this line to the end of the .bashrc file:
PS1='\[\033[0;35m\]\h\[\033[0;33m\] \w\[\033[00m\]: 'The chunks like “0;35m” and “0;33m” are what control the colors – those are pink and brown, for example. Other colors you can substitute include “0;32m” for green and “0;36m” for blue — it’s just a matter of changing those numbers.
Other important parts of that jumbled collection of characters are “\h” and “\w”, which represent the hostname and working directory, respectively. If you wanted to include your username in the prompt you could add the “\u” code along with an “@” symbol, and it would look like this:
PS1='\[\033[0;35m\]\u@\h\[\033[0;33m\] \w\[\033[00m\]: 'Before we see what that will look like, however, let’s also look at another useful feature of your shell, aliases.
Alias
The “alias” keyword lets you set a shortcut for another command. Some examples to get you started, which can be added to the end of your .bashrc file:
alias free="free -m"
alias update="sudo aptitude update"
alias install="sudo aptitude install"
alias upgrade="sudo aptitude safe-upgrade"
alias remove="sudo aptitude remove"They’re pretty simple examples, and are just meant to save you a little typing. Notice that you can essentially replace a command with an alias, like we did by setting the alias “free” to be a shortcut for “free -m”. With that alias set, when you type “free” on the command line, behind the scenes the shell actually runs “free -m”, so you don’t have to type the extra characters to get the memory usage numbers in megabytes.
Similarly, those other aliases are shorthand for some aptitude commands to update or install packages. Since “sudo” is run behind the scenes you’ll still have to type your password, but at least before that you won’t have to type as much to run an update or install a package.
To activate the changes you’ve made to the .bashrc file, either log out and log back in or enter this command:
source ~/.bashrcIf you set a value for “PS1″ above, you’ll see your prompt change. Feel free to go back and change the colors or format of the prompt, or add your own aliases.
Set locale
You can check the current locale setting for your slice by running:
/usr/bin/localeIf the code doesn’t match what it should be for the localization you would like to use for your slice (or if it uses a generic locale like ‘POSIX’), run something like the following commands:
sudo /usr/sbin/locale-gen en_US.UTF-8
sudo /usr/sbin/update-locale LANG=en_US.UTF-8‘Something like’ because you may want to use a locale other than US English. If so, substitute the language code for ‘en’ and the region code for ‘US’ above. The locale ‘cy_GB.UTF-8′ would designate Welsh for the language and Great Britain for the region, for example. A complete list of language and region codes can be found here.
If you change the default locale for your slice you will need to log out and log back in to see the change when running ‘locale’ by itself again.
Package repositories
An Ubuntu Slice comes with a basic set of repositories.
Have a look at the enabled repositories by running:
sudo nano /etc/apt/sources.listYou should see something very much like:
deb http://archive.ubuntu.com/ubuntu/ karmic main restricted universe
deb-src http://archive.ubuntu.com/ubuntu/ karmic main restricted universe
deb http://archive.ubuntu.com/ubuntu/ karmic-updates main restricted universe
deb-src http://archive.ubuntu.com/ubuntu/ karmic-updates main restricted universe
deb http://security.ubuntu.com/ubuntu karmic-security main restricted universe
deb-src http://security.ubuntu.com/ubuntu karmic-security main restricted universeEach line specifies either a binary package repository (‘deb’) or a source package repository (‘deb-src’).
You can, of course, add more repositories whenever you want to but I would just give a word of caution: Some of the available repositories are not officially supported and may not receive any security updates should a flaw be discovered.
Keep in mind it is a server we are building and security and stability are paramount.
Update
Now we can update the package list that aptitude uses.
sudo aptitude updateNOTE: If you have used the .bashrc aliases shown above you just need to enter ‘update’ as the alias will use the entire command. I’ve put the whole thing here so you know what is happening.
Now we have set the locale and updated the sources.list repositories, let’s see if there are any upgraded packages available:
sudo aptitude safe-upgradeAs with all installs have a careful look at the list and, once happy, press ‘y’ to continue.
That’s really the basics done for the Slice.
Once any updates have been installed, we can move on to installing some essential packages.
Development Tools
Ubuntu has some handy meta-packages that include sets of pre-defined programs required for a single purpose.
So instead of installing a dozen different package names, you can install just one meta-package. One such package is called ‘build-essential’. Issue the command:
sudo aptitude install build-essentialNotice the programs that are to be installed include gcc, make, patch and so on. All these are needed for many other programs to install properly. A neat system indeed.
Enter ‘y’ and install them.
Now we have the necessary packages should we want to build an application from source.
Done
The console is now informative and less drab, locales have been configured and basic compile tools have been installed. Quite a lot happening here but now we have a more secured Slice with updated packages ready for the meat of the server to be put in place.
