sudo apt-get install zerofree

If the package cannot be found, try enabling Multiverse repository (Software Sources).

Find out which drive you want to shrink

df

Run zerofree

sudo zerofree /dev/sda1

Once finished, shut down the Virtualbox machine and use Virtualbox to compact the hard disk image file

VBoxManage modifyvdi /path/to/the/image.vdi compact

Done.

After a brief research, I’ve decided to install Dovecot and getmail to accomplish the above.

First step was to install Dovecot:

sudo apt-get install dovecot-imapd

Then I followed instructions from Dovecot website, set the location of IMAP mail directories and configured it to use SSL connections only. I have also modified standard port in /etc/dovecot/dovecot.conf from 993 to a different one:

protocol imap {
ssl_listen = *:7777
}

Restarted Dovecot

sudo /etc/init.d/dovecot restart

and tested my first IMAP account using Thunderbird. As the SSL certificate I used on the server was self-signed, Thunderbird complained about it but that can be ignored and SSL certificate saved.

After that, I installed getmail:

sudo apt-get install getmail4

For each mailbox I wanted to download from a POP3 server, I defined a separate config file for getmail:

[retriever]
type = SimplePOP3Retriever
server = mailserver
username = user
password = pass

[destination]
type = Maildir
path = ~/Maildir/


Note that emails will be saved into Maildir directory within home directory of a particular user. Maildir is also the format in which emails will be saved. This configuration works nicely with Dovecot when serving emails.

The last step was to set up a cron job to fetch emails from POP3 and save them into IMAP folder:

crontab -e
* * * * * getmail -d >> getmail.log


where “-d” means it will delete messages from the server after downloading them.

getmail can also load multiple config files at once, so if you have more then one account to fetch:

getmail -d -r configfile1 -r configfile2

Conky is a free, light-weight system monitor for X, that displays any information on your desktop.

Here is a screenshot of my configuration:

To get the same:

$ sudo apt-get install conky
$ vi .conkyrc

paste the contents of this conky config:

… save the file, download and extract this archive into your home directory (cd ~) and run

$ conky

Please note that I have removed CPUs 2-4 from the config to make it more compatible with single processor systems. Full list of Conky variables.

If you wish to monitor a remote Ubuntu computer and display conky’s output on your desktop:

$ scp .conkyrc scp username@remoteserver:
$ ssh -X username@remoteserver
$ sudo apt-get install conky
$ conky

UPDATE: If your server doesn’t have Xorg installed (which most don’t), you can use {execi} to issue commands over ssh and grep the info you need. The below part of conkyrc is based on a Ubuntu Jaunty server, your distribution may vary in where some of the details are stored.
${voffset 30}
${execi 43200 ssh vds hostname} ${hr 2}
${voffset 2}${font OpenLogos:size=16}u${font}   Kernel:  ${alignr}${execi 43200 ssh vds uname -r}
${execi 43200 ssh vds less /proc/cpuinfo | head -n 5 | tail -n 1 | cut -d @ -f 2 | cut -c 2-} ${alignr}Load: ${execi 60 ssh vds uptime |cut -d , -f 4- | cut -c 17-}
${execibar 60 ssh vds bash ~/cpuload.sh}
${execigraph 60 ssh vds bash ~/cpuload.sh}
${font StyleBats:size=16}q${font}   Uptime: ${alignr}${execi 60 ssh vds uptime |cut -d , -f 1 | cut -c 2-}
${font StyleBats:size=16}q${font}   Users logged in: ${alignr}${execi 60 ssh vds w | head -n 1 | cut -d \  -f 7- | cut -d \, -f1}

HD ${hr 2}
${execi 600 ssh vds df -h | head -n2 | tail -n1 | cut -c 24-}
${voffset 4}${execibar 600 ssh vds df -h | head -n2 | tail -n1 | cut -c 41-42}

NETWORK ${hr 2}
${voffset 4}${font PizzaDude Bullets:size=14}N${font}   Download: ${alignr}${execi 600 ssh vds ifconfig | head -n 8 | tail -n 1 | cut -d \( -f 2 | cut -d \) -f 1}
${voffset 4}${font PizzaDude Bullets:size=14}T${font}   Upload: ${alignr}${execi 600 ssh vds ifconfig | head -n 8 | tail -n 1 | cut -d \( -f 3 | cut -d \) -f 1}
${voffset 4}${font PizzaDude Bullets:size=14}b${font}   Public IP: ${alignr}${execi 43200 ssh vds ifconfig | head -n 2 | tail -n 1 | cut -c 21- | cut -d \  -f 1}

TOP: ${hr 2}
${voffset 4}${execi 60 ssh vds ps -eo pcpu,pid,user,args | sort -k 1 -r | head -5}

Note that if you run both local and remote conky, you may need to amend conky’s position on the remote server in .conkyrc so they won’t overlap.

To start conky from a remote computer and have it displayed on yours, create this as a .sh script and run:

ssh -X username@remoteserver 'conky'

And finally, if you wish to start conky automatically after your log in, create a bash script with the following and add it into your Ubuntu start up programs:

#!/bin/bash
sleep 20 && conky;

Halting it for 20 seconds prevents compiz from applying border and drop down shadows etc. to conky’s window.

$ cd /etc/gdm/PostSession
$ sudo vi Default

add your commands before “exit 0″, for example:

...
sudo fusermount -u /home/juraj/shareA/
sudo fusermount -u /home/juraj/shareB/
exit 0

Save (:wq) and give it a go - restart or logoff. Tested in Ubuntu 8.10

compizconfig-settings-manager
This manager includes endless compiz configuration options including burning of windows on closing, Mac-like window effects and much more.

gnome-color-chooser
Allows to customise Gnome colours - panels, desktop, icons etc. Try these 220 Gnome colour schemes