There is a new way to quickly search and access menu and indicator actions, called the "HUD" (Heads-Up Display). Tap the Alt key and enter some letters and words, and it will show the corresponding entries, including some fuzzy matching; then press enter to execute the action. The search will include all menu entries of the currently focused application, as well as all indicator facilities (like managing emails, sound list, or logging out of the session). It learns from your previous choices to make the search more and more accurate for you.
System Settings has several new "options" to customize Unity's look and behavior.
Nautilus quicklist support has been added to Unity launcher.
ClickPad devices are trackpads where the physical button is integrated into the trackpad surface. Ubuntu 12.04 now has enhanced support for these devices. When the button is pressed on a ClickPad device, a second finger may be used to drag the cursor.
ClickPad support requires extra handling that conflicts with "Click Action" support. Click Actions allow for separate actions when multiple fingers are active on a trackpad. The default Ubuntu settings enable right button behavior when two fingers are in contact with the trackpad surface and the physical trackpad button is pressed. Because of conflicting behavior, ClickPad devices do not support Click Actions in this release.
Most Synaptics brand ClickPads are recognized out of the box. Apple MacBook trackpads are recognized as well. Support for Apple Magic Trackpads and more Synaptics brand ClickPads will follow in the next release.
Network Manager now uses dnsmasq for improved DNS reliability and support for split-DNS on VPN links. You can learn more here.
IPv6 and IPv4 are now equally supported in Network Manager: an IPv4 address is no longer required for a connection to be considered as working.
The default music player has been switched to Rhythmbox, which again includes the Ubuntu One music store.
LibreOffice has been updated to 3.5.2.
GNOME has been updated to 3.4.1. Read the GNOME 3.4 Release Notes to learn what's new and improved. A few highlights include:
-- Files (Nautilus) now has undo support.
-- Several games have been modernized with useful help, simplified menus, and a less cluttered interface.
Remmina with FreeRDP is the new standard remote desktop client, replacing Vinagre and rdesktop.
The IcedTea Java plugin is no longer installed as part of the ubuntu-restricted-addons package but it is still available for install (889171)
When installing new software through software-center, corresponding language support packages (translations, spell check modules particulat to that software, help files, etc.) are now installed alongside automatically. This removes the need to open "Language Support" after installing new software.
The user can opt-in into personalized recommendations. This will show global, category and per-application recommendations to the user.
Payment support for PayPal.
Web Directory to share applications with your friends.
Support for multiple screenshots and videos is now available.
Startup time and overall responsiveness was improved.
Improved support for installing multiple versions via the ubuntu-backports project.
The all new Control Panel now provides an installer, setup wizard, ability to add/remove folders to sync, and more.
Proxy support is now fully functional.
Ubuntu One contacts sync in Evolution is not supported any more and has been removed.
Up until Ubuntu 11.10, administrator access using the sudo tool was granted via the "admin" Unix group. In Ubuntu 12.04, administrator access will be granted via the "sudo" group. This makes Ubuntu more consistent with the upstream implementation and Debian. For compatibility purposes, the "admin" group will continue to provide sudo/administrator access in 12.04.
Hibernate (suspend to disk) has been disabled by default, as it was found to be unreliable, very slow and confusing to have two suspend modes. See bug 812394 for details. If you want to re-enable it, please follow this recipe.
pm-utils now has two new scripts to power down USB and various PCI devices in battery mode. A number of desktop packages were fixed to wake up less often. Both of these reduce power consumption and thus improve battery lifetime.
resolvconf is now used to manage /etc/resolv.conf on all Ubuntu systems. You can learn more here
Backports are now more easily accessible --- to enable users to more easily receive new versions of software, the Ubuntu Backports repository is now enabled by default. Packages from backports will not be installed by default — they must explicitly be selected in package management software. However, once installed, packages from backports will automatically be upgraded to newer versions.
DVD Images --- the DVD images have been cleaned up significantly reducing their size to around 1.5GB to ease consumption. The remaining software remains available via download.
Linux v3.2.14 Kernel
Ubuntu 12.04 LTS ships with an updated kernel moving from the mainline v3.0 series to the mainline v3.2 series. At release we are shipping with the Ubuntu 3.2.0-23.36 kernel which is based on the v3.2.14 upstream stable Linux kernel. The mainline v3.0 to v3.2 stable series update brings a number of new features. Some highlights include:
ext4 gains support for larger base block sizes
btrfs has more work addressing data integrity issues
device mapper gains thin provisioning and recursive snapshots
more work to improve performance under high writeback load
networking improvements for congested networks
ext3 moves to using filesystem barriers
memory allocator improvements
VFS scalability improvements
a new iSCSI implementation
software wait gains bad block management
Key changes in the Ubuntu kernel since the 3.0.0-12.20 Ubuntu kernel as shipped in the 11.10 Ubuntu release include:
Rebase to upstream stable Linux kernel v3.2.14.
The amd64 -generic and -server kernel flavors have been merged into a single -generic kernel flavor for Ubuntu 12.04. Given the few differences that existed between the two flavors, it only made sense to merge the two and reduce the overall maintenance burden over the life of this LTS release.
Support for a new armhf kernel flavor has been introduced.
The non-smp PowerPC kernel flavor has been removed. All hardware currently supported by the non-smp PowerPC kernel flavor should also be supported by the smp PowerPC kernel flavor.
RC6 is enabled by default for Sandy Bridge systems. RC6 is a technology which allows the GPU to go into a very low power consumption state when the GPU is idle (down to 0W). It results in considerable power savings when this stage is activated. When comparing under idle loads with machine state where RC6 is disabled, improved power usage of around 40-60% has been witnessed.
An improved set of jack detection patches has been backported from the upstream v3.3 Linux kernel.
An updated AppArmor patch set has been included to better align with what is landing upstream.
Applied and enabled the seccomp filters feature which uses the packet filtering machinery (BPF) to restrict access to system calls.
A set of kexec fixes for arm from v3.3-rc1 has also been backported.
We've also conducted an extensive review of Ubuntu kernel configs and made numerous config changes as a result.
Upstart has been updated to version 1.5. More details are available in the Upstart Technical Overview.
Ubuntu 12.04 is distributed with a default toolchain that includes: GCC 4.6.3 (and changes from Linaro GCC 4.6-2012.02), binutils 2.22, eglibc 2.15, and Linaro gdb 7.4-2012.04.
Compared to the 11.10 release the toolchain did see only incremental changes and bug fixes; comparing to the 10.04 LTS release, GCC updates include
Updated frontends for better standards support (Ada 2012, Objective-C 2.0, improved experimental support for the upcoming C++0x ISO C++ standard, Fortran 2003 and 2008 improvements, new Go frontend)
Improved optimizations, including better inter-procedural optimizations, and link time optimization (LTO).
Further information can be found upstream (GCC-4.6, GCC-4.5, binutils, gas, ld, gdb).
Ubuntu 12.04 includes Python 2.7.3 and Python 3.2.3 Python 2.6 is no longer available for install.
There is expanded support for Python 3 in this release, with Python 3 ports of python-dbus, python-feedparser, germinate, lazr.ui, wadllib, python-defer, python-keyring, and python-qt4 now included, among others.
The default run time for Java is OpenJDK 6b24 (IcedTea 1.11.1). OpenJDK 7u3 (IcedTea 2.1) is available in the archive as well.