Thursday, August 2. 2007
Xnest is a nested X server: a display that runs in a window within another display. It's useful for testing GUI applications as a different user, trying out several desktop environments at the same time, or getting screenshots of the login process.
If you're using the default Fedora display manager (graphical login screen), Gdm, then you can start an Xnest session using gdmflexiserver:
$ gdmflexiserver -nThis instructs Gdm to present a login prompt on an Xnest display. Using the Option or You can adjust the appearance of this display using gdmsetup.
Alternately, you can run Xnest with an XDMCP query or broadcast request (you'll need to configure the display manager to respond to XDMCP):
$ Xnest -query loginserver :20 # Requests a session prompt from loginserverOr you can start Xnest with a particular client or desktop environment:
$ Xnest -ac :20 -nolisten tcp & xterm -display :20Xnest uses the underlying X server's processing capabilities--it doesn't draw the nested image, it simply proxies the X requests to the parent server. It hasn't been actively updated in a few years, though, so it does not handle newer extensions such as RENDER.
Watch for coverage of Xephyr, an alternative nested X server, next Thursday.
Installing from the command line: yum install xorg-x11-server-Xnest
Installing using the graphical installer: Base System > X Window System > xorg-x11-server-Xnest
Menu location after installation: (None)
Command: /usr/bin/Xnest (note the uppercase letter X)
Upstream website: http://x.org/
Thursday, July 26. 2007
Seamonkey is maintained by a dedicated group of Mozilla volunteers who incorporate code from the main Mozilla projects such as Firefox and Thunderbird. I do almost all of my browsing in Firefox, but my daughters use Seamonkey Composer to create personal web pages.
Installing from the command line: yum install seamonkey
Thursday, July 19. 2007
Hwbrowser is a very simple tool that provides read-only access to hardware information. Although the same information is available in more detailed form using command-line tools such as fdisk, lsusb, and lspci, it can be handy to have this information available in a point-and-click format, especially if you are supporting an inexperienced user remotely over the telephone.
This package was suggested by Ahsan. If you'd like to suggest a package, please form on the right side of the front page.
Installing from the command line: yum install hwbrowser
Thursday, July 12. 2007
Logical Volume Management is a powerful way of managing disk data. LVM enables you to move data between disks, add or remove disks, change volume sizes, and make frozen snapshots of data while your system is running. Any Fedora system administrator should be learn the command-line tools used to administer LVM, because they're essential if you need to perform system recovery work or remote storage adminisitration.
System-config-lvm provides a graphical interface to the LVM tools (and related utilities, including fsck and resize2fs) which is good for non-emergency storage administration. It enables you to manage your logical volume and filesystem configuration with a few mouse clicks, and it prevents potentially-disasterous command-line mistakes such as reducing a logical volume size before reducing the filesystem contained within that volume.
(One word of warning: system-config-lvm does not recognize RAID elements as being in use, and therefore lists them as "Unitnitialized Entities". If you are using a LVM-on-RAID configuration, system-config-lvm will let you wipe out RAID elements by making them into PVs. Be careful!)
Installing from the command line: yum install system-config-lvm
Thursday, July 5. 2007
The GNOME project has often eschewed customizability, ostensibly favoring usability. This has led to endless discussion with many arguments put forth both for and against extensive customizability of the user interface.
Installing from the command line: yum install gtweakui
Thursday, June 28. 2007
VNC is a cross-platform, lightweight remote display protocol originally developed and released under the GPL by Oracle & Olivetti Research Labs in Cambridge, England. The labs were sold to AT&T and eventually closed. Some of the original developers formed RealVNC Ltd to promote and commercialize the technology, and other developers created TightVNC as a friendly competing implementation. There are nearly 100 open-source projects available that use VNC technology (including VNCsharp, a C# implementation created by my colleague David Humphrey at Seneca College).
On a Windows or Mac platform, VNC is usually used to share the single GUI desktop with other users. In a Linux (or Unix) environment such as Fedora, VNC can be used to do much more -- there are literally dozens of possible ways to use VNC because the platform is inherently multiuser.
Fedora includes vino (Gnome) and krfb (KDE) which are tools for sharing the Fedora desktop like a Windows or Mac system would share the desktop: the local user and the remote user see the same image and can both interact with the display. These programs have the advantage of being user-configurable (they are on the menus and don't require root access to set up) and you can disconnect from a session and reconnect to it later. However, since they are started after login, they can only be used if someone is already logged in on the local X server display.
The Fedora vnc-server package provides a special X server (Xvnc) that does not draw onto a video card, but instead draws only on to a remote VNC display. The included vncserver script uses this to create a session in addition to the one displayed on the local screen, enabling remote GUI access that does not affect or interfere with the local GUI desktop.
The vnc-server also package includes an interesting module which can be loaded into the X.org server permitting simultaneous local and remote display; since this is started when the X server starts, you can use it to remotely login to a system as any valid user.
But perhaps more importantly, Xvnc has an inetd mode, which can be configured to work with the xinetd and gdm servers to provide on-demand remote desktops. If no one is connected to the VNC service, no Xvnc servers are started; if five people connect, then five servers are started.
Thursday, June 21. 2007
Editing cascading style sheet files (CSS) can be a huge chore. Cssed is a text editor for CSS files. It includes on-line references, syntax highlighting, and auto-completion.
So far, that sounds like any programmer's editor -- but what sets Cssed apart is the built-in CSS validator, CSS value and property insertion, and wizards to aid in determining selectors, setting colours, and developing box properties.
Cssed provides a unique and convenient environment for editing CSS files.
Installing from the command line: yum install cssed
Thursday, May 24. 2007
Beagle is a desktop search tool integrated into many different parts of Fedora. It indexes your e-mail, recently viewed web pages, documents, spreadsheets, and even your instant messages for rapid searching. On the GNOME desktop, the Places menu's Search option opens a Beagle search window.
For KDE users, the optional Kerry Beagle package provides a front end to Beagle, integrated with other KDE tools such as the system tray and Konqueror. When you start KDE after installing Kerry, you will see an icon in your system tray that looks like a beagle wearing a kerchief; clicking on this icon will display the beagle search window shown in today's screenshot. From there you can easily search your desktop using the same search conventions used by most web search engines (and you can also configure Beagle indexing using the Configure button).
Installing from the command line: yum install kerry
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