The official Debian GNU/Linux distribution now ships on 7 to 8 binary DVDs or 44 to 53 binary CDs (depending on the architecture) and 6 source DVDs or 33 source CDs. Additionally, there is a multi-arch DVD, with a subset of the release for the amd64 and i386 architectures, along with the source code. Debian GNU/Linux is also released as Blu-ray (BD) images, 2 each for the amd64 and i386 architectures, or one for the source code. For size reasons, some very large packages are omitted from the CD builds; these packages fit better in the DVD and BD builds, so are still included there.

A new feature with squeeze is the addition of isohybrid support to the i386 and amd64 CDs, DVDs and BDs. To make a USB stick bootable with one of these images used to mean following some extra procedures after downloading the image; instead, now all that is required is to simply write the image directly to the USB stick. For more information please see the “Preparing Files for USB Memory Stick Booting” section in the Installation Guide.

Some drivers included in the Linux kernel used to contain non-free firmware blobs. Starting from squeeze this firmware has been moved to separate packages in the non-free section of the archive, such as firmware-linux. If such packages are installed, the firmware will be loaded automatically when required.

The preferred program for interactive package management from a terminal is aptitude. For a non-interactive command line interface for package management, it is recommended to use apt-get. apt-get is also the preferred tool for upgrades between major releases. If you are still using dselect, you should switch to aptitude as the official front-end for package management.

For squeeze APT automatically installs recommended packages by default^[2]. This can be changed by adding the following line in /etc/apt/apt.conf:

APT::Install-Recommends "false";

An important improvement in the Debian GNU/Linux boot system is the introduction of dependency-based boot sequencing and parallel boot. This feature is enabled by default in new installs and it will be enabled for upgrades from lenny, if possible.

This feature is enabled through the use of insserv by sysv-rc to order init.d scripts based on their declared dependencies^[3]. It has been possible after a sustained effort to adapt all the boot scripts of packages provided in the distribution as well as the boot system itself.

With dependency-based boot sequencing it is also now possible to run the boot system scripts in parallel which can, under most circumstances, improve the speed of the boot process. This feature is enabled by default, in new systems and upgrades, whenever possible. To disable it specify

CONCURRENCY=none

in /etc/default/rcS. For more information on this feature refer to the information available in /usr/share/doc/insserv/README.Debian.

In this new release, the settings for the keyboard have been unified so that both the console and the Xorg server use the same settings. The keyboard settings are now defined in the /etc/default/keyboard configuration file which overrides the keyboard defined in Xorg's configuration file.

The console-setup package now handles the keyboard for both environments as well as the font configuration for the console. You can reconfigure the keyboard layout and related settings by executing dpkg-reconfigure keyboard-configuration or by manually editing the /etc/default/keyboard configuration file.

Graphics mode setting code for the most common desktop chipsets (from Intel, ATI/AMD and NVIDIA) has moved from the respective Xorg drivers to the Linux kernel. This provides a number of advantages, such as:

More details are in Section 5.7, “Graphics stack changes” and in the Debian wiki.

This Debian release comes with several options for implementing client-side authentication using LDAP. Users of the libnss-ldap and libpam-ldap packages should consider upgrading to libnss-ldapd and libpam-ldapd.

These newer packages delegate the LDAP queries to a central unprivileged daemon (nslcd) that provides separation between the process using the LDAP information and the daemon performing LDAP queries. This simplifies handling of secured LDAP connections, LDAP authentication credentials, provides a simpler mechanism to perform connection fail-over and debugging and avoids loading LDAP and related libraries into most applications.

Upgrading to libnss-ldapd and libpam-ldapd should be easy as existing configuration information will be mostly reused. Only for advanced configuration should any manual reconfiguration be necessary.

These packages however currently lack support for nested groups and only support password change using the LDAP password modify EXOP operation.

Some packages from proposed-updates may also be made available via the squeeze-updates mechanism. This path will be used for updates which many users may wish to install on their systems before the next point release is made, such as updates to virus scanners and timezone data. All packages from squeeze-updates will be included in point releases.

Note that this replaces the functionality previously provided by the volatile.debian.org archive.

In order to use packages from squeeze-updates, you can add an entry to your sources.list:

deb     http://mirrors.kernel.org/debian squeeze-updates main contrib
deb-src http://mirrors.kernel.org/debian squeeze-updates main contrib

The next time you run apt-get update, the system will become aware of the packages in the squeeze-updates section and will consider them when looking for packages to upgrade.

Note that if APT::Default-Release is set in your /etc/apt/apt.conf (or in any of /etc/apt/apt.conf.d/*), then, in order for automatic upgrades to work, it is necessary to add the following configuration block into /etc/apt/preferences (see apt_preferences(5) for more information):

Package: *
Pin: release o=Debian GNU/Linux,n=squeeze-updates
Pin-Priority: 990

When a new package is made available via squeeze-updates, this will be announced on the debian-stable-announce mailing list.

The service provided by the backports.org repositories has been integrated in Debian infrastructure and is now an official Debian service, hosted at backports.debian.org.