GUI Thursday

The Linux filesystem permission model comes from Unix. It provides three permissions (read, write, and execute) for three communities (the user that owns the file, users in the group that owns the file, and all other users). The beauty of this model is its simplicity: it's easy to understand and compact to display. By creating various groups of users, this scheme can accommodate most use cases.

But sometimes the traditional model just isn't convenient, and having many different groups becomes a real pain to manage. Filesystem access control lists (ACLs) mend this pain by extending the traditional model to permit individual permissions to be set for any number of users and groups.

The setfacl and getfacl commands are used to manage ACLs from the command line, and ls -l will display a plus-sign beside the permission of any file which has an extended access control list:

$ ls -l ~/Desktop/lux-handout
-rw-rw-r--+ 1 chris chris 821 2008-05-03 15:21 /home/chris/Desktop/lux-handout

The Eiciel package provides a graphical user interface for managing ACLs. Although this package provides a stand-alone application, it really shines as a Nautilus extension -- if you're using Gnome, simply right-click on a file and select Properties, and you'll see an Access Control List tab with the Eiciel display.

Note: ACLs are only available on filesystem that support extended attributes. Fortunately, this includes ext2/ext3/ext4 (the default filesystems in Fedora), JFS, and ReiserFS. However, FAT, NTFS, NFS, and CIFS (Samba) do not support ACLs at this time.

Bug: The Eiciel display includes a checkbox labeled "Also show system participants". You will need to check this box to see users with a user ID below 1000. This control is intended to hide system accounts such as root and mysql, but on a Fedora system, regular user IDs start at 500, not 1000. See bug 445667 for details.

Installing from the command line: yum install eiciel
Installing using the graphical installer: Base System > System Tools > eiciel
Menu location after installation: Applications > System Tools > Eiciel or right-click on a file within Nautilus, select Properties, go to the Access Control List tab
Command: /usr/bin/eiciel
Upstream website: http://rofi.roger-ferrer.org/eiciel/

Fedora offers many tools for viewing detailed hardware information, including lsusb, lspci, hdparm, and direct access to the /proc and /sys filesystems. An alternative tool, lshw, combines this information and more into a single, unified listing -- but the output often exceeds 1000 lines.

lshw-gui provides a convenient graphical interface into this rich source of information, enabling you to easily drill down into the specific details of each subsystem and device. The display shows four panes of information -- three narrow panes on the left to navigate though the tree of device details, and a larger one on the right to view details of the selected node.

This program displays a lot more information than tools such as hwbrowser and does a good job of translating arcane device details into a very readable format.

Installing from the command line: yum install lshw-gui
Installing using the graphical installer: Not available in the Browse view; use the Search or List views to install lshw-gui
Menu location after installation: Applications > System Tools > Hardware Lister
Command: /usr/bin/lshw-gui
Upstream website: http://ezix.org/project/wiki/HardwareLiSter (lshw-gui is referred to as gtk-lshw on the upstream site)

HP printers and multifunction units are well supported in Fedora, thanks in large measure to HP's decision to open-source its driver software and utilities (hplip) in cooperation with related projects such as sane, ghostscript, and cups. The hplip-gui package provides a simple, convenient GUI front-end to these tools, making it easy to scan and print documents, access photo cards, and control copy and fax functions. hplip-gui also provides access to useful device information such as toner and ink levels.

The HP Device Manager displays a list of available devices and provides a point-and-click interface to the features of each model. External programs such as xsane are leveraged where appropriate, and other capabilities are provided directly by the device manager.

Installing from the command line: yum install hplip-gui
Installing using the graphical installer: not available through the Browse view; use the Search or List views to install hplip-gui
Menu location after installation: System>Administration>HP Device Manager
Command: /usr/bin/hp-toolbox
Upstream website: http://hplip.sourceforge.net/

For many years Unix and Linux systems have offered convenient online documentation in the form of manpages. These documents provide short, concise information about commands, applications, file formats, APIs, and interfaces. They use a simple markup and can be easily processed for display in a terminal or online help application, converted to PDF, printed using PostScript, or posted to the web as an HTML page.

ManEdit is a graphical editor intended to simplify the task of creating and maintaining manpages. Its user interface displays two panes: the left pane presents a list of the sections in the current manpage (right-click for options), and the right side provides a space for editing the title and text of a selected section. The syntax used is an XML variation of the traditional manpage markup, and controls are provided for inserting basic markup such as bold and underline tags. The Preview button will display a basic preview of the man page.

Although ManEdit is still a bit rough around the edges, it provides a convient way to quickly write a manpage, especially if you are unfamiliar with manpage markup.

Note: The current version of ManEdit crashes if the New button is pressed. Bug 356171 is open regarding this issue. As a work-around, open an existing manpage (from one of the directories in /usr/share/man), edit it, and save it into a new file.

Using manpages:
To view a manpage using a graphical viewer: Use the GNOME or KDE help viewers (yelp or khelpviewer), accessible using the bouy icon on your panel bar.
To view a manpage from a shell prompt: man command (to find out which commands might perform a certain task, try man -k keyword or apropos keyword)
To print a manpage: man -t command | lpr
To convert a manpage to PDF format: man -t command | ps2pdf - > outputfile.pdf
To prepare an html version of a manpage: gunzip <$(man --path command) | man2html >outputfile.html

Installing from the command line: yum install manedit
Installing using the graphical installer: Development > Development tools > manedit
Menu location after installation: Applications > Programming > ManEdit
Command: /usr/bin/manedit
Upstream website: http://wolfpack.twu.net/ManEdit/

Many current open source projects do not have manpages for their software. Please consider writing a manpage for your favorite program and submitting it to the program author!

The bible is a unique book: It's an all-time bestseller which has sparked controversy, been quoted in many different contexts, and had influence in language and culture in many parts of the world.

BibleTime is a tool for searching, reading, and studying the bible. It is a KDE application that builds on libraries from the Sword project, which also provides the bible texts, commentaries, concordances, and other modules that can be used with BibleTime. Features of the software include simultaneous access to multiple versions of the bible text, rapid searching, and easy access to cross-references and commentary.

Installing from the command line: yum install bibletime
Installing using the graphical installer: Not available in Browse mode; use the Search or List modes to install bibletime
Menu location after installation: > Applications > Accessories > BibleTime 1.6.3.b
Command: /usr/bin/bibletime
Upstream website: http://www.bibletime.info/

Fedora 8 is quickly approaching: the first test release is available, the second test release is scheduled to come out in less than two weeks, and with Live CD images, it's easier than ever to participate in testing. The preferred method for downloading Fedora installation images is BitTorrent via the tracker at http://torrent.fedoraproject.org/

There are quite a few BitTorrent clients available in the Fedora repositories. One of the newest is Transmission, which offers some of the most useful features of the highly-regarded Azureus client (including PEX - peer exchange of information traditionally sent through the tracker), but is a native binary and does not require Java. It is has a lightweight design and a sleek but informative user interface -- definitely worth checking out!

Installing from the command line: yum install transmission
Installing using the graphical installer: Applications > Graphical Internet > transmission
Menu location after installation: > Applications > Internet > Transmission
Command: /usr/bin/transmission-gtk
Upstream website: http://transmission.m0k.org/

If you're interested in monitoring your system's performance, but want to see more information than the GNOME System Monitor applet can display, GKrellM is the tool for you. It's the Swiss army knife of graphical monitoring tools, offering more than a dozen built-in monitors (which run in a single process) and supporting both plugins and themes.

Once installed, GKrellM is available on the System Tools submenu. Pressing the PgUp or PgDown keys while the GKrellM window is focused will cycle through available themes, and right-clicking on the GKrellM window will open the configuration window (as shown in the screenshot) with hundreds of options available for fine-tuning the information presented (you may need to experiment -- right-clicking on different parts of the window may open different configuration dialogs).

A number of GKrellM plugins are available from the Fedora repositories, including analog, sun, and moon clocks, a frequency monitor, hard disk temperature display, weather monitor, and more. The gkjrellm-themes package includes a number of additional themes for customizing the program's appearance.

Installing from the command line: yum install gkrellm
Installing using the graphical installer: Base System > System Tools > gkrellm
Menu location after installation: > Applications > System Tools > GKrellM System Monitor
Command: /usr/bin/gkrellm
Upstream website: http://members.dslextreme.com/users/billw/gkrellm/gkrellm.html

Xephyr is an alternative to the Xnest nested X server mentioned last week. Both of these programs provide a nested X display -- drawing into a window on a parent X server instead of drawing directly onto a hardware screen -- but they accomplish this in very different ways. Xnest proxies X requests to the parent server (not actually performing the operations itself), while Xephyr acts on each request and draws onto an X image, which is then displayed in a window on the parent server.

This means that Xephyr can handle requests which the parent server cannot handle. For example, it can offer the RENDER extension (enabling clients to quickly display anti-aliased text) even when the parent display does not have the RENDER extension.

Unfortunately, gdm does not know about Xephyr, so you can't use it with gdmflexiserver in the same way that you can use Xnest. However, if you have enabled XDMCP ("remote login"), you can start Xephyr manually and have it request a session login prompt from gdm:

$ Xephyr -query localhost -screen 800x600 :1

Where localhost is the XDMCP server, 800x600 is the desired screen resolution, and :1 is the display number (use any number which is not already in use).

Installing from the command line: yum install xorg-x11-server-Xephyr
Installing using the graphical installer: Not available in Browse mode; use the search or list modes to install xorg-x11-server-Xephyr
Menu location after installation: (None)
Command: /usr/bin/Xephyr (note the uppercase letter X)
Upstream website: http://x.org/