Go to the Citrix Web site, look for the XenApp Linux client and download it. Copy the downloaded file into your chroot system. In your chrooted session, untar the Citrix client file. After decompression, you should have a new folder named linuxx86 and a few extra files, including the install script called setupwfc. To install, as root, execute ./setupwfc, and answer the text wizard questions. You may have to fill in some dependencies for your distro, but after a few moments, your LTSP image will be Citrix-enabled.
The Citrix server configuration is beyond the scope of this article. You should start with a working Citrix XenApp Server. The good news is that you don't even need to be one of the Citrix server administrators at your company, you just need to have the user name and password for an account with published applications on the server. In other words, if you already have access to a desktop or an application via Citrix, you can set up that connection as one of the screens on your multisession terminal server. Simply log in to your Citrix session as a regular user and download the session definition ICA file (Figure 5). ICA files are actually text files that contain the information and settings to establish a connection to a XenApp server. The easiest way to download this file is to right-click on one of the icons displayed on your Citrix server Web interface and select Save link as.
Once you have your ICA file, copy it to the Citrix client install directory on your chroot session:
$ cp my-ica-file.ica /usr/lib/ICAClient/desktop.ica
Now, let's create the screen script for the Citrix session in /usr/share/ltsp/screen.d. We'll call this script citrix1:
#!/bin/sh # Copy the ica file to a temp file because # wfica deletes the file on execution. cp /usr/lib/ICAClient/desktop.ica \ /usr/lib/ICAClient/temp-file-desktop.ica sudo xinit /usr/lib/ICAClient/wfica \ /usr/lib/ICAClient/temp-file-desktop.ica
Notice that XenApp is the new name for the Citrix presentation server, so any Citrix server XenApp or presentation server will work.
Finally, exit your chroot session and add the new screen parameter for the citrix1 script in your lts.conf file. It should look like this:
[default] ... SCREEN_05 = citrix1
Now you can rebuild your LTSP image with the ltsp-update-image command, and test the Citrix session on your PXE boot client when you press Ctrl-Alt-F5.
The rdesktop client and script are included in the LTSP install package, so you won't have to create scripts or install new packages. All you need to do is include their screen parameters in the lts.conf file. Your final file should look like this:
[default] VNC_OPTIONS = "-FullColor -passwd /usr/share/ltsp/vnc-passwd" VNC_SERVER = your.mac.ip.address RDP_OPTIONS = "-a 16" RDP_SERVER = your.windowsTS.ip.address SCREEN_01 = shell SCREEN_02 = rdesktop SCREEN_03 = ldm SCREEN_04 = vnc1 SCREEN_05 = citrix
This time, you don't need to run ltsp-update-image. When you use the /var/lib/tftpboot/ltsp/i386/lts.conf file, it's read directly from the server and not from the ltsp-image. Be aware that there is another lts.conf file inside the chroot directory; avoid using that one.
If you've tested each step of your progress, you surely know by now that sometimes different “screens” suddenly take over the monitor output. They seem to be fighting each other to be top dog. This is not a bug. It happens when a remote session login screen timeouts. Windows and Citrix wait patiently for your login credentials, but after some inactivity time, they drop your connection. When this happens, X dies. Then your LTSP terminal restarts X and restarts the connection. This pulls the visible screen to the newly started X screen, taking over the monitor output.
To avoid this effect, you need to log in to all of your available sessions. Logged-in sessions also have timeouts, but they are much longer.
The simplest solution is based on an idea I found in an older version (from LTSP 3.0) of the rdesktop script. The script included a “read” statement just before the xinit call. That way, users had to press a key to start their rdesktop session. You can use that same approach. It's not fancy, but it works.
A more stylish solution is to use zgv to show a picture just before the session start line. zgv closes when users press the Enter or Esc key. Remember to add a “Press Enter to start” banner to your image.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide