tar

Using tar

Some basic usage examples of tar.

Archive a set of files:

tar -cvf tarfile.tar /var/log/syslog /var/log/messages

Archive and compress (gzip) a set of files:

tar -cvzf file.tar.gz /var/log/syslog /var/log/messages

Archive and compress (bzip2) a set of files:

tar -cvjf file.tar.bz2 /var/log/syslog /var/log/messages

Extract a tar file:

tar -xvf file.tar
tar -xvzf file.tar.gz
tar -xvjf file.tar.bz2

Display the content of a tar file:

tar -tvf file.tar
tar -tvzf file.tar.gz
tar -tvjf file.tar.bz2

SquidGuard

SquidGuard is a URL redirector used to use blacklists with the proxysoftware Squid. There are two big advantages to squidguard: it is fast and it is free.
NCurses Disk Usage

A disk usage analyzer with an ncurses interface, aimed to be run on a remote server where you don't have an entire gaphical setup, but have to do with a simple SSH connection. ncdu aims to be fast, simple and easy to use, and should be able to run in any minimal POSIX-like environment with ncurses installed.
WPKG

WPKG is an automated software deployment, upgrade and removal program for Windows.

It can be used to push/pull software packages, such as Service Packs, hotfixes, or program installations from a central server (for example, Samba or Active Directory) to a number of workstations.

It can run as a service to install software in the background (silent install), without user interaction.

It can install MSI, InstallShield, PackagefortheWeb, Inno Setup, Nullsoft, other software installers or .exe packages, .bat and .cmd scripts and similar: no more repackaging to perform software installation.

WPKG is open source software.
opsi

opsi (Open PC Server Integration) the Open Source client management system
Vagrant

Vagrant is a tool for building complete development environments. With an easy-to-use workflow and focus on automation, Vagrant lowers development environment setup time, increases development/production parity, and makes the "works on my machine" excuse a relic of the past.