Most important change here is the way how network printing works. Formerly, a CUPS-specific mechanism was used. The server broadcasted information about the printers it shares and the clients listen to these broadcasts making the printers available on the client side, looking like local print queues for the applications.
Recently, the Printer Working Group (PWG), an association of printer and software industry for developing standards related to digital printing, has created a standard for broadcasting information about shared printers. This standard is broadcasting the information via Bonjour, a protocol also used for many other network services, like shared files systems, screens, music/video servers, …
CUPS has adopted this standard in 1.6.x, but only broadcasts and does not listen to broadcasts of CUPS daemons (or generally print servers using Bonjour) on other machines, letting remote printers not automatically get available locally. CUPS also dropped the old broadcasting protocol without transition period.
To overcome the problems and keeping network printing as easy as before (this is why 10 years ago the distros switched to CUPS) the cups-filters project ofOpenPrinting introduced cups-browsed, an extra daemon which by default listens to Bonjour broadcasts of remote CUPS daemons (of IPP printers coming soon) and automatically creates local print queues pointing to the shared printers making pure CUPS 1.6.x networks working out-of-the-box.
If your network still contains machines running CUPS 1.5.x and older, cups-browsed also has legacy support for the old CUPS broadcasting, browsing (listening), and BrowsePoll. Please see the comments in /etc/cups/cups-browsed.conf, edit the file appropriately, and restart cups-browsed (“sudo restart cups-browsed”) or reboot. When upgrading to Raring, BrowsePoll directives are overtaken from CUPS to cups-browsed automatically.
For everyone developing embedded or mobile systems based on Ubuntu, the CUPS package is split up into more binary packages to get a minimum client-only printing stack, of the packages cups-daemon, libcups2, and cups-browsed, occupying only ~1 MB. This only listens for Bonjour broadcasts (legacy CUPS broadcasts and BrowsePoll optional) of remote CUPS servers and makes the printers available locally. No drivers and filters for locally connected printers are available then.
Another thing to mention which was available before but never told about in release notes: When sharing local printers they are automatically available also for Apple’s iOS devices (iPhone, iPad, iPod touch).
We eventually intend to ship only Python 3 with the Ubuntu desktop image, not Python 2. The Ubuntu 13.04 image continues this process, although we will not be able to convert everything to Python 3 for Ubuntu 13.04 final image.
If you have your own programs based on Python 2, fear not! Python 2 will continue to be available (as the python package) for the foreseeable future. However, to best support future versions of Ubuntu you should consider porting your code to Python 3. Python/3 has some advice and resources on this.
Automatic Apport crash reporting has been enabled by default again to catch problems early on. It now checks for duplicates on the client side, which will avoid uploading debug data and creating Launchpad bug reports unnecessarily in many cases now.
Software Updater in 13.04 has a simplified details panel that most prominently shows applications and manually-installed packages. Libraries and packages that belong to the base system are collected under a single item.
Upstart User Sessions (technology preview)
This Ubuntu release includes a “tech preview” of Upstart User Sessions, which allow Upstart to supervise a user’s desktop session. This feature is disabled by default for Ubuntu 13.04, but can be manually enabled for testing.
To enable Upstart User Sessions for all users:
- Uncomment “ubuntu” in file /etc/upstart-xsessions.
- Logout of any desktop sessions.
- Login to the default Unity session.
To disable, simply comment out “ubuntu“, logout and log back in again.
Social networking for 13.04 is now handled by the Friends service, which replaces the backend Gwibber provided in previous Ubuntu releases. There is no transition required, if you have social networking accounts setup in Ubuntu Online Accounts, the Friends service will just work. The Gwibber lens in Unity has been replaced with a Friends lens and works in much the same way. The Gwibber client application is no longer included by default, for similar functionality friends-app can be installed from Software Center.