Some problems and their solutions

In the mysterious world of computers you will, every now and then, find problems which perhaps will not be very easy to solve. Below you will find some of those I have found myself using Ubuntu 12.04.

Mysql

Permission issues

This is a free database program which could be installed by using Ubuntu Software Center. The problem was how to start using it. First of all you have one "server" program called mysqld. This program is started automatically by default. Then there is a client program, called mysql, which communicates with mysqld. As a novice you will probably just try to use the command mysql but this just lead to a number of permission issues. It is possible to stop the server and restart it with the command, mysqld --skip-grant-tables, but so far I have not found out how to do this automatically. The proper solution, however, seems to be, to start mysql with the command, "mysql -u mysql". All of a sudden everything seems to work OK.

Stop a command

Sometimes when you write on the mysql command line mysql cannot understand what you are writing and gives you a > for completing things. If you do not know what to write, try the \c command in order to stop the command. If not disaster might occur.

Djvu graphics

In the Ubuntu software center you can find the djvu program which is used for graphics. I have never been able to use it in the form of a plugin to Firefox. Instead, use another older plugin which seems to work. I think I use the one called djvulibre-plugin for the version Hardy, 3.5.20-2.

Gtk+ for Windows

It is possible to use the same C-code both for Linux and for Windows. One way of doing this is to install the programs MinGW and Gtk+ for Windows. It is probably possible to compile the program under Linux and use it under Windows but I did not manage to do this. Instead, I have used the gcc compilers under Windows, e.g. "mingw32-gcc.exe". One big problem was to find all libraries and compiler options to use. In Linux you normally use the pkg-config when compiling. There is such a program also for Windows but this does not seem to work for disks other than C:. So, in order to find the files you must put them on the disk called C.

PHP programs and web servers

Sometimes you want to write to a server file by using a php script. It seems that you will normally not have the permissions to do so. Ask the server owner to create the file you want to change and then it will have proper permissions set.

Error while loading shared libraries:

This message shows up if a program in Linux does want to use some shared libraries, but cannot find them. It might be possible to use a command line statement as:

export LD_LIBRARY_PATH=$the_library

and after this run "sudo ldconfig". If you want to always include the library in the PATH you can use a file in the directory "/etc/ld.so.conf.d". Make a file e.g. myfile.conf and just write the path in the file. Look at the other files in the directory.

TV Usb stick Pinnacle 330e

Ubuntu 12.04 does not have full support for this old USB stick "TV-card". In order to solve this issue you must:

Ascertain that the stick is actually found by the computer, use the command lsusb and check the output.
Download three so called firmware files, drxd-a2-1.1.fw, drxd-b1-1.1.fw and xc3028-v27.fw. Put them in /lib/firmware. Reboot!
Use dmesg to check if the files seem to operate.
Use e.g. Kaffeine for checking if television channels can be viewed.
If some channels are lacking you can use the program w_scan in order to find them. Use a comand similar to this: w_scan -c SE -x >> channels.txt. Note that SE is Sweden. Open the file channels.txt and put the text lines from w_scan, in the channel list, scanfile.dvb. Make a tag such as [dvb-t/se-Kurt] and put it plus the channels in scanfile.dvb according to the alphabet. See how the other tags are ordered. Normally you have two such files, but put the text only in the local directory scanfile.dvb, i.e. your own. Change the date under the [date] tag so you can see that the proper file is used.
For some mysterious reason you must delete your previously scanned channels in the Kaffeine channels list and restart Kaffeine. If not, Kaffeine only scans a few channels.