Update Notifier Applet

Latest news: project has moved

Today (June 14 2016) I decided to move un-applet from sourceforge.
I did so because the recent changes to sourceforge's services rendered un-applet's debian repository virtually unusable, presumably because of a bug in current versions of apt, that stops apt from handling http(s) redirections implemented by sourceforge correctly, causing "apt-get update" to fail with somewhat odd (and probably misleading) error messages (see also below).

The good news is that the friendly folks from TuxFamily accepted to host the project, so you can reach the project's home page now at unapplet.tuxfamily.org , the new download area is located at download.tuxfamily.org/unapplet .

If you want to use un-applet's debian repository, you can get the gpg-key with:

# wget -O - http://download.tuxfamily.org/unapplet/debian/key/deb.gpg.key | apt-key add -

resp. on systems without root login:

$ sudo wget -O - http://download.tuxfamily.org/unapplet/debian/key/deb.gpg.key | apt-key add -

and then add the following line to /etc/apt/sources.list (or use your favourite package management application to add the repository):

deb http://download.tuxfamily.org/unapplet/debian debian main

For now I will also keep the files here on sourceforge, but there will of course be no more updates to this site, so please update your bookmarks.

I am sorry for the inconvenience.

Thanks to the people at sourceforge for the free hosting and their excellent service, and good-bye!

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Description

UN-Applet provides a simple applet for the system tray that informs the user about available software updates on Debian linux based systems, as Ubuntu, Linux Mint and of course Debian.
The main goal of un-applet is to provide an easy way to help users to keep their system up to date without getting in the user's way while keeping software dependencies at a minimum.
It should work with any panel-like application that conforms to the freedesktop.org system tray specifications; it has been tested with IceWm, Lxde, xfce4, KDE and Gnome, most likely other desktop environment's panels should be fine, too.
KDE or Gnome libraries are not required to run un-applet.

Dependencies

un-applet requires the following packages to be installed:

• Python and Tkinter (package python-tk)
• wget
• the Tktray extension to Tcl/Tk (package tk-tktray)
• gettext
• gksu
• one of xvt, rxvt-unicode (a.k.a. urxvt) or mlterm (MultiLingualTerminal) as terminal emulator program
• for older systems that still use Tcl/Tk-8.5, as Debian Wheezy, the tk image library is needed (package libtk-img)
• and of course a desktop environment with a working system tray

News

June 13 2016: un-applet_1.0 released!

I am glad to finally announce the stable version 1.0 of un-applet!
This version features a number of major improvements plus a (presumably unpleasant) change affecting the supported terminal emulator programs:

• As a consequence of the bug in konsole described in the "News" entry below I decided that un-applet now supports only three different terminal emulator programs that have thoroughly been tested to work flawlessly together with the applet:
  • xvt: a really old-fashioned terminal with a minimal footprint (only about 40 kB download size, less than 80 kB installed size), which is still a fully working solution for users with english locale or some european locales that do not use many non-latin1 characters. Xvt does not support unicode, however and so it is likely to be a poor choice for asian, african or even some european locales (as greek, russian etc.).
  • rxvt-unicode (urxvt): a very advanced xterm alternative with excellent unicode support. urxvt is a very good choice for most locales. It is about 750 kB to download and 3000 kB installed size.
    There are also a slightly smaller package named rxvt-unicode-lite and a rxvt-unicode-256color version which are also supported.
  • mlterm (the Multi-Lingual-Terminal): this is a terminal with very sophisticated unicode support that should hopefully be able to handle any possible locale. If you experience problems with urxvt you might want to give mlterm a try. However, mlterm is about 2 MB to download and about 10 MB installed size. There is also a slightly smaller mlterm-tiny variant which is also supported.
  • The default dependency, if none of these is already installed, is rxvt-unicode.
    The appearance of the terminal emulator window can now be adjusted from un-applet's Preferences dialog.
  I am sorry for the inconvenience, but as mentioned earlier, the situation with KDE / konsole is truly embarrassing, and so I did not want to risk another surprise of that kind.
• A new option DIST_UPGRADE in /etc/un-applet/un-applet.conf now allows to choose how the upgrade process will be performed. If set to "1" (default) apt-get dist-upgrade will be used, if set to "0", apt-get upgrade will be used instead. The latter may especially be desired on potentially "unstable" distributions like debian testing.
• The automatic search for pending updates now uses a random delay from 0 to 3000 sec. (0-50 min.) to avoid problems caused by too many users trying to connect to mirror servers at the same time.
• Eye candy: besides the default 22x22 px tray icons I added two more icon themes borrowed from Gnome and Linux Mint in various sizes from 16 - 48 px, so hopefully everyone will find a tray icon theme that suits their taste.
• Besides this there is a number of smaller bugs that have been fixed plus some improvements to the UI.

Repository bug
Unfortunately sourceforge decided to apply some changes to their service that renders un-applet's package repository virtually useless. This seems to have something to do with the way https redirection is implemented and a failure of apt to handle this correctly. Oddly enough the repo still seems to work with an outdated version of LMDE (which is basically Debian Jessie at testing stage without any updates for the last two years or so), but it fails with current versions of apt as found today in Jessie, Stretch, Ubuntu Trusty and so on. In any case now sourceforge only supports https, so the respective line in your /etc/apt/sources.list file needs to be changed into

deb https://sourceforge.net/projects/un-applet/files/debian debian main

You will also need to have the package apt-transport-https installed in order to use the repo.
Still, depending on the distro in use, a subsequent apt-get update will probably fail with on or other error message. See here for details about this problem.
I apologize for the inconvenience, but I am afraid this is not in my hands.
I am working on a solution for this, which might well end in moving the project to a different hosting service, so please stay tuned.

IceWM problems
There is a bug in older versions of IceWM (i.e. for example the version 1.3.8-2 from Debian Jessie, as well as the "official" 1.3.8 from IceWM's sourceforge page) that causes uncontrollable "zombie" windows to appear on the screen if any application that requests the system tray is launched too early during window manager startup. To work around this, earlier versions of un-applet had a hard-coded two second time-out before the applet actually started. This time-out can now be increased from the preferences dialog, if necessary (for users of other desktop environments it should be safe to set this to 0).
This bug has apparently been fixed in the latest versions of IceWM (currently 1.3.8+githubmod+20150914+fa3fdef-2), however unfortunately for the worse, because a new bug was introduced that stops TkTray icons from being displayed properly in the IceWm system tray.
A bug report on this issue has been acknowledged as valid by debian's IceWM maintainers, so there may be hope that this will be resolved in subsequent releases (see here for details).

Aug. 25 2015:

A nasty bug in the KDE terminal application konsole has been reported to render un-applet virtually unusable when konsole is used as terminal emulator program, which will probably be the case for the majority of KDE users.
Please see for example this forum thread for a more detailed description of the bug.
Apparently the problem lies deep in the internals of KDE's underlying Qt-library.
At least on Ubuntu Trusty with KDE-4.13 the bug is still present.
Unfortunately the only solution for un-applet I can offer is to use a different terminal emulator program.
In case you have no other terminal programs installed you might want to try one of several light-weight alternatives as for example xvt or, in case you need utf-8 support, rxvt-unicode
I am currently trying to figure out how to best work around this issue, which might very well result in hard-coding the use of one or other terminal program.

Aug. 24 2015:

I finally set up a debian repository for un-applet!
If you would like to be notified about new releases now all you have to do is to add my gpg-key to you keyring by running (as root) on debian systems:

# wget -O - http://sourceforge.net/projects/un-applet/files/debian/key/deb.gpg.key | apt-key add -

resp. on Ubuntu (or other systems without root login):

$ sudo wget -O - http://sourceforge.net/projects/un-applet/files/debian/key/deb.gpg.key | apt-key add -

Then add the following line to /etc/apt/sources.list or use your favourite package management application to add the repository:

deb http://sourceforge.net/projects/un-applet/files/debian debian main

After the next update of the package database un-applet's repository will be active.
The repository currently only supports i386 and amd64 archtectures; if you miss your architecture please send me a note. Since it is the same package for any architecture anyway, it would be easy to add if I know that someone actually needs it.

Aug. 05 2015: un-applet_0.4

This release fixes a bug that could have caused false negative results when the package database was locked by another process while the cron script tried to check for available updates. Now the script tests if /var/lib/dpkg/status is locked before actually updating the package database. If it is, the call to apt-get update will be silently postponed until the script is called the next time.

July 19 2015: un-applet_0.3

Initial release.

Download

un-applet is available for download on its sourceforge site

License

un-applet is licensed under the terms of the Gnu General Public License.
The package includes several portions of third party code, please consult the file /usr/share/doc/un-applet/README.3rdParty for details and copyright notices.

Installation:

Please download the latest version from the sourceforge project page. To install the applet, simply install the .deb package with

    # dpkg -i un-applet_<version>_all.deb

or the graphical package installer of your choice. If you want to have a look at the files the package contains first, you can download the .tar.bz2 archive instead of the .deb package, extract its contents and view the files within the source tree. You may then build your own package from the sources with

    $ fakeroot dpkg -b un-applet_<version>_all

Usage:

Once the debian package is installed, you should find a main menu entry "Update Notifier Applet" under either "System" or "System" -> "Package Management", depending on the desktop environment in use. Of course you can also start the applet simply by calling

    $ un-applet

How it works:

The core functionality is in fact not provided by the applet itself, but by a simple script that is installed into /etc/cron.hourly and thus executed once an hour with root privilege.
This script (by default) first tries to determine if an applet process is actually active, if not it does nothing.
In the next step it checks if the pre-defined interval between updates of the package database (default three hrs.) is expired, if not, again it stops and does nothing.
Finally, if the above conditions are met, it calls a helper script un-applet-update-pkgdatabase in order to obtain information about pending updates.
This script (by default) first runs the un-applet-verify-mirrors script to check if all of the software mirrors defined in /etc/apt/sources.list and (if present) /etc/apt/sources.list.d/*.list can be reached. This is done to work around a bug in apt-get that has been observed when apt-pinning is used (which may well be the case if you never consciously decided to do so, for example if a debian-backports mirror is in use), that may lead to a considerable amount of packages accidentally selected for upgrade if one or more mirrors can not be accessed.
Next thing, it checks if the package database is locked by another process, and if yes, stops and does nothing, in order to avoid false negative results.
If everything is ok, it calls

    apt-get update

and creates a list of pending updates, if any.
Finally the script writes the number of available upgrades, the names of the upgradable packages and the time of its last execution into three files in /var/lib/un-applet.

The applet itself simply periodically checks the contents of these files and changes its color accordingly:

• green: no pending updates, system is up-to-date.
• orange: updates available.
• red: some kind of error (probably a temporarily locked package database or unreachable mirror server(s)) occured.

If updates are available, you can click on the icon and will be prompted with a yes/no dialog box that asks you if you want to perform the upgrade now. If you choose yes, a gksu prompt will show up, which starts up a terminal emulator that runs the un-applet-dist-upgrade script which basically calls

    apt-get (dist-)upgrade

to install the upgrades.
The icon has also a context menu which allows you to manually start the update of the package database or lets you open a list with information about pending updates (if any).

Configuration:

The behavior of the cron script and its helpers can be customized by editing the file /etc/un-applet/un-applet.conf . In particular the time interval between updates of the package database and the command to install pending updates (apt-get upgrade vs. apt-get dist-upgrade) might be things that you would want to change.
Please consult the comments in this file for more details.

As far as the applet itself is concerned, you can configure a few things through the applet's Preferences... dialog:

• Time interval for polling (default 10 min.):
  defines how often the applet checks the results of the cron script (and its helper scripts). This does not affect the time interval between updates of the package database. This check is done in a tiny fraction of a second, so there should be no need to increase the value.
• Startup delay (default 2 sec.):
  delay between program start and creation of the tray icon. This is (probably) only needed for older versions of IceWm (see above). For most users it should be safe to set this to 0.
• Graphical administrator login command (default: gksu):
  defines which command to use for administrator login. On systems without root-login (as a standard Ubuntu install) you would have to use gksudo instead of gksu. However, if everything is configured properly, gksu's smart internal logic will decide automagically which is the right thing to do. On misconfigured systems you might have to change this into "gksudo" to work around a spoiled gksu-configuration, though. If you want, you can of course try to use an altogether different administrator login program, probably the KDE variant or others will work, too (although I never tried it).
• Terminal emulator options:
  allows you to choose one of the supported terminal applications (if more than one is installed).
  There is also a number of hopefully self-explanatory appearance options for the terminal that can be adjusted.

Bugs

• The debian package does not list libtk-img as dependency, this may cause fatal errors on older OS versions unless libtk-img is manually installed with

      apt-get install libtk-img

  however I did not want to force users with current OS versions to install software they don't actually need.
  There also are no dependencies that make sure that there actually is a system tray avilable.
• After starting the applet for the first time you will get a red icon, indicating that some kind of error has occured. This is normal, because the cron script that updates the package database has not yet been running then, and thus the files it will create (and the applet will evaluate) are not yet present. If you do not want to wait for cron, you can make the icon happy by running "Update package database..." once from the context menu, and if all goes well you will get a green or orange icon, depending on the up-to-dateness of your system.
• Some people might find it annoying that the applet refuses to update the package database because one or more mirrors defined in their /etc/apt/sources.list resp. /etc/apt/sources.list.d/*.list files are temporarily or permanently not reachable, which however does not stop other programs from updating their systems.
  This is not a bug but intentional; in fact this is to work around a bug in apt-get that may cause packages accidentally to be selected for upgrade if one or more mirror servers can not be reached, in fact this may happen even if you do not have any network connection at all. In a worst case this might lead to hundreds of unwanted updates to be installed if you do not watch very closely what you are doing.
  This bug in apt-get has been observed when apt-pinning is used (which may be the case, even if you personally never consciously decided to do so, e.g. if you use a debian-backports mirror).
  To avoid this, the cron script by default checks if all of the mirrors defined in your sources.list file(s) are actually reachable before updating the package database. You can turn this feature off by setting VERIFY_MIRRORS="0" in /etc/un-applet/un-applet.conf , but this is not recommended. If one or more mirrors cause persisting problems you should seriously consider to replace or eliminate these from your configuration instead, please remember that a core part of your system is affected and that the fact that other programs silently ignore this does not necessarily mean that there is nothing wrong.

Contact

Any comments, bug reports and suggestions are highly welcome.
Please mailto:
Michael Lange <klappnase (at) users (dot) sourceforge (dot) net>

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