Klaus Knopper answers your Linux questions

Ask Klaus

Article from Issue 177/2015
Author(s):

Klaus addresses problems with Wheezy updates, Adobe Flash, dial-up settings, and mountpoint dates.

Wheezing Wheezy

Hi Klaus: In Knoppix 7.5.0, all of a sudden there is an error message that appears every time I want to install or update a software package:

sudo apt-get update
sudo apt-get install <packagename>
Reading package lists... Done
E: The value 'wheezy' is invalid for
  APT::Default-Release as such a
  release is not available in the
  sources

How can I fix this?

Knoppix is based on Debian GNU/Linux. Shortly after the release of Knoppix 7.5.0, Debian released the new "Jessie" version and dropped the name "Wheezy" for the previous "stable" release. To avoid problems with upgrades, I had explicitly written "Wheezy" as the repository branch for Knoppix version 7.5.0 in the config file for software manager apt-get, which is now causing the error message because of the disappeared software branch.

It's easy to repair: Just edit /etc/apt/apt.conf.d/00knoppix:

sudo leafpad /etc/apt/apt.conf.d/00knoppix

and change the line

APT::Default-Release "wheezy";

to one of the following:

APT::Default-Release "jessie";
APT::Default-Release "stable";

Save the file, then rerun the software catalog update,

sudo apt-get update

and the problem should be gone.

Flashback

Dear Sir, I installed Knoppix 7.5 from the Linux Magazine April 2015 DVD to a USB dongle. My PC with Windows 8.1 is an Intel NUC. Knoppix works very well – Windows 8.1 is terrible; unfortunately, I need it for some things I will use with the NUC.

I hope to use Knoppix to surf the Internet. Unfortunately, many times (e.g., in Facebook), you meet with videos that need Adobe Flash. Even if I use the Chromium browser, the videos do not work.

The Knoppix 7.5 published in Linux Magazine seems to be very difficult to get running with Adobe Flash or something like that. Could you please tell me how to solve that problem? Or is there some forum or mailing list where I could present this question?

Yours sincerely,

Heikki Pesonen, Oulu, Finland

For installing the proprietary Flash player browser plugin, the Debian package flashplugin-nonfree is needed. During installation, it downloads an archive containing the plugin from the vendor's website and extracts the software to the system-wide plugin repository. Installation of the flashplugin-nonfree package can be triggered by selecting Knoppix | install components. You'll see the Flash package listed in the Install Software dialog (Figure 1).

Figure 1: The Flash package is listed in the Install Software dialog.

With Knoppix 7.5, you may have hit the problem mentioned in the previous question that Debian just released "Jessie" as the "stable" branch, and the "Wheezy" branch that Knoppix used as its former base is now gone. You will see this when trying to install the plugin manually by

sudo apt-get update
sudo apt-get install flashplugin-nonfree

Using the install components menu item (Figure 2) will tell you that the Flash installation failed for the same reason. The recipe in the previous question – setting the default base to "Jessie" or "stable" – will fix that problem.

Figure 2: Flash installation.

Personally, I try to get along without the proprietary Flash plugin, and most videos today are playable with the standard HTML5 embedded video formats (VP8/WebM), which most browsers can play without additional plugins. The proprietary Flash plugin has a bad history of being vulnerable and unstable, potentially compromising the browser's security. In Knoppix, the NoScript plugin will let you chose to activate the plugin only for specific websites and ask for permission to do so as an additional layer of security. Watch out for the corresponding browser messages: The NoScript logo near the address field lets you change the settings at any time.

Dial-Up Setup

Dear Sir: While I do not have WiFi at home, I can access WiFi wherever it is offered. I currently use DSL or dial-up at home. I am wondering how to set up either with Knoppix 7.5.

Also, I have disks from previous issues that contain programs that I would like to use. Programs such as RawTherapee, FlightGear, Gramps, and so on. What is the best way of taking them from the disk or downloading from the Internet and making them usable with Knoppix 7.5?

Thanks, Gary

DSL and dial-up setups are somewhat more complicated than DHCP with WiFi or LAN. Additionally, how well they are supported and how configurable may depend on the manufacturer's specifications for your network device. When plugging in the device, check the NetworkManager menu for settings options. If the device doesn't appear, it might not be supported.

Some DSL boxes can be set to handle authentication and autoconnect on their own, and they can handle connected computers just like DHCP clients, as in a LAN network. If your DSL router has that option, it may be the easiest way to get connected: Just activate the settings in the router's web interface. You can find some hints about DSL and dial-up setups for Ubuntu at the Debian Admin site [1], but using the New connection dialog in NetworkManager may help you find the adapter for configuration (right mouse button over the Connection applet).

About program installations: Assuming you have already transferred Knoppix to a USB flash disk successfully and your computer has Internet access, you can update the software database, search for programs and install packages with the commands in Table 1, prefixed by sudo so you have write access to system directories.

Table 1

Package Installation Commands

Command

Effect

apt-get update

Update software package database

apt-cache search <keyword>

Search for packages matching given keywords

apt-cache show <packagename>

Show details of package

apt-get install <packagename>

Install or update package and dependencies

apt-get install -t unstable <packagename>

Install or update package and its dependencies from the "unstable" Debian branch, which may contain newer versions

apt-get --purge remove <packagename>

Remove package, including its configuration files and data

The procedure of installing the FlightGear simulator would be

sudo apt-get update
sudo apt-get install -t unstable flightgear

which will download 1GB of compressed software packages (37 packages with dependencies; I counted), which will decompress to 2GB, so you will need a minimum of 3GB free space on the second (Linux-formatted) partition of your Knoppix USB flash disk. After installation, you can free up the Apt tool's download cache by doing

sudo apt-get clean

to get 1GB back.

Of course, you can also use the graphical Synaptic tool for this instead of the Apt command-line interface.

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