Last time we saw how bash can help us in handling default values out of the box using parameter expansion. This time we will see how basic string operations (nonetheless common and useful) can also be achieved using bash.

There is many ways to do string manipulation with bash, like finding a filename extension using expr, separating the directory part from a filename using dirname and basename…. or even more sophisticated ones based on regex, sed….

Why using a sledgehammer to crack a nut when you could use bash builtin functionalities!

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Bash is a sh-compatible command language interpreter that executes commands read from the standard input or from a file.
There is much more to bash than running a sequence of commands, one of the features bundled with bash is parameter expansion.

Any shell user has most likely used shell variables, be it $1 or $myvar, to save values… but there is more to it. This tutorial will cover a subset of shell parameter expansion that can become really handy and save you a lot of time.

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OpenVPN is a SSL based VPN software that runs on most OS. It is simple to install and run.

In this tutorial, I will go over the steps needed to configure OpenVPN on Debian Squeeze to provide a full VPN tunnel, this is particularly useful when you want to access internet from non-trusted networks such as free hotspots…

There are many ways of setting up OpenVPN, a common one is to use a unique certificate for each users. Another one is to have each user authenticate with a username/password.

In this article, we will be setting OpenVPN to authenticate users using PAM.

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I already spoke about Terminator a while back. Since then,, quite some time has passed and lots of features were added…

In the last 7+ months, cmsj as worked a lot on getting the whole architecture re-implemented in a more object-like architecture which makes the different component of Terminator interact together more naturally.

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There is a few software that will use the editor command to find out what text editor to use. Example commands will be dch to add a new .deb changelog entry, revision control softwares when prompting for a commit message …

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Lately, I have been experiencing a funny network issue when using VMware Workstation VMs with NAT interface. Roughly, the IP network was working fine, but DNS resolution was not anymore. It happened intermittently, but I could see that this mainly happened when I was suspending my laptop, going to another location and resuming.

Forcing the VM to use a public DNS would solve the issue.

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3. Setting BGP

As told earlier on, vyatta-bgp1 will advertise AS 1 with network 1.1.1.0/24 to its neighbor vyatta-bgp2 handling AS 2
and
vyatta-bgp2 will advertise AS 2 with network 2.2.2.0/24 to its neighbor vyatta-bgp1 handling AS 1

They will use a common password for this communication, which is BGPtutorial.

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2. Setting the network interfaces

During this part, we are going to set up the 2 Border Gateway routers’network interfaces. In vyatta world, you need to enter the interactive configuration shell by typing:

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Vyatta is a Linux based distro that ease the set up of VPN, Routers, antivirus…. It has a really small footprint on your system as it only requires something like 800M to be installed and is based on Debian. On the top of that, it offers configuration wrappers to facilitate service settings.

This tutorial will explain how to set up 2 Border Gateway Protocol (BGP) boxes to route the traffic from one Autonomous System (AS) to the other using Vyatta.
Vyatta Community Edition 4.1.4 was used during this set up.

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Bazaar (bzr) is a distributed version control system (VCS) sponsored by Canonical and thus bzr is widely used by the Ubuntu community.

Like any vcs, bzr will let you track the different version of your code locally and let you push the changes to a remote server.

One cool feature of bzr is that you can maintain a remote copy of your code history without having a bzr server running, nor having a copy of bzr on the remote server running and simply by using ssh to transport the data.

This tutorial will not explain how bzr works, but will show the couple few step to create your local repository, add a few files, commit the changes, push them to a remote server and copy the branch newly created to another machine.

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