Debian Package of the Day (static archived copy)

Article submitted by Maurizio Pedraglio. We are running out of articles! Please help DPOTD and submit good articles about software you like!

Clusterssh is a graphical utility that allows you to open several ssh connections and execute commands simultaneously in all of them. I find it powerful in many cases, for example when I’ve to perform a dist-upgrade on many different servers.

It provides a small window to control the sessions, and one xterm window for each one of them. Here are some screen shots using it on Ubuntu and Gnome 2.20.

You can open a ssh session simply clicking on “Host” and then “Add Host”.

Type user@server in the “Add Host” window and a new shell will appear in a new window.

You’ll be able to open n different ssh session versus n hosts. You should focus the input box in the controlling window to send commands to all the shells at once.

If you want to execute a command only in a single host, simply focus the right shell. The other shells won’t receive anything, and the command will take effect only on the selected host.

If you want to detach a shell from the parallel command execution, simple uncheck it in the “Host” menu. In the case below commands will be executed on host 192.168.15.104 and localhost1 but not on localhost

Others commands available: use “Toggle active state“ to uncheck all host; “Retile” allows you to reorganise windows in the desktop. Clusterssh can also be launched from the command line, just type in a shell:

cssh serverA serverB … serverN

Clusterssh has been available both in Debian and Ubuntu since a long time ago

Article submitted by Tomas Pospisek. Please help DPOTD by submitting good articles about software you like!

VirtualBox is a piece of software that uses virtualisation to simulate a PC. With it you can run Windows, Open BSD or even Linux from your Debian system. Since it also runs on Windows and Mac OS, you can use it to run Debian from that other non-free OS. Note however that it only works on x86 and x86_64 hosts.

You can use it if you want to test or have a look at a live CD distribution or to help the KDE project test the new KDE4 without messing up your current desktop.

You can do all this in a nice and hassle free GUI, driven by menus or application wizards. Here you can see the mentioned "KDE Four Live" CD booted up and ready within VirtualBox.

VirtualBox requires to load its own set of kernel modules and won’t start without them. There is a package providing pre-built modules for the stock kernels in testing, you will need to manually install the correct version for your kernel. If those packages doesn’t suit you, you will need to compile them; the standard Debian way to do this would be:

$ sudo apt-get install virtualbox-ose virtualbox-ose-sources module-assistant
$ sudo module-assistant prepare virtualbox-ose
$ sudo module-assistant auto-install virtualbox-ose
$ ls /usr/src/virtualbox-ose-modules-*
$ sudo dpkg -i /usr/src/virtualbox-ose-modules-*.deb

That last line will need to be re-written to pick the virtualbox-ose-modules package that corresponds to your kernel.

You’ll also need to add the users that should be allowed to run VirtualBox to the vboxusers group. I’m adding the current user here:

$ sudo adduser `whoami` vboxusers

Now you have to re-login so that your process context picks up the fact that you now belong to then vboxusers group. You can do that by "su"ing into yourself:

$ su `whoami` -

And here you go:

$ virtualbox

Note for those who like to know how it works: VirtualBox tries to run native code whenever possible, when it’s necessary it uses dynamic recompilation as QEMU does. It also moves guest code intended to run on ring 0 to ring 1, and because of this it doesn’t use the VMX features from the processor too much. See the technical documentation for details.

The virtualbox-ose package is available in Debian testing and unstable, and in Ubuntu since Gutsy (if you’re thinking of upgrading to testing, be sure you are aware of the implications, before doing so!). There’s also a backport to the currently stable Debian "etch" release.