User Tools

Site Tools


Ham Radio







Problems with DNS lookups after update of Windows 10

After an update of Windows 10 I had problems with the DNS. All name resolutions worked sporadically only a short time after restart. The solution is simple. You start a shell as administrator and do the following:

netsh int ip reset [ENTER]
netsh winsock reset [ENTER]
ipconfig /flushdns [ENTER]

Then restart once and the DNS queries should work again.

Shutdown timeout with systemd

Sometimes I have the problem with Lubuntu 18.04 LTS on a Thinkpad T430S, that a shutdown needs a long time. Mostly the problem is Samba, which does not stop in the specified time. During shutdown you got a message like this on console:

A stop job is running for Session [..]

The systemd starts and stops processes. For stopping jobs there is an timeout of 90s. This is certainly appropriate for servers, especially when databases are running, but much too long for a client system.

To change this timeout you have to edit /etc/systemd/systemd.conf:


Simple uncomment the line which defines this timeout, 'DefaultTimeoutStopSec' and change the value as you like.

You should not enter a value, which is rather low. I use 10s, I think this is for an client computer without local databases or similar software fine. Anyway, I only have the problem with the Samba client.

Merge sorted PDF files

I had the problem that I had to merge 326 PDF files into one. These files are catalog pages of an online flip catalog that was not available as a single download file. So I saved all these single pages, the file names are bk_1.pdf, bk_2.pdf …. bk_326.pdf.

To create a PDF file from these files, I use pdfjam (also known as pdfjoin). The problem was that the file list is not sorted, so the resulting PDF file doesn't have the correct page order. pdfjam can't sort the input files, so we need something else for that.

This task could be done by the tools find and sort. But, the sort parameter is not at the beginning of the filename, so we need a sort option to do this job properly and pass the resulting filename as input to pdfjam.

find ../Downloads -name bk_*.pdf -print | sort -V | xargs pdfjam --landscape -o catalog.pdf

This command line finds any file with the pattern bk_*.pdf and the result is sorted. You need the -V option to sort these filenames with a number in the middle of the alphanumeric filename. The result is the input of xargs, which then calls pdfjam with the sorted list of filenames.

Apple Bluetooth keyboard with Lubuntu

I use a Thinkpad T430 for Ham Radio applications with the small Bluetooth Keyboard from Apple. The keyboard has a UK layout. That's no problem with Lubuntu, you only have to choose “Keyboard - English (UK) - English (UK, Macintosh)”.

This small keyboard has no “Delete” key, normally it is mapped to FN+Backspace. Because I don't need the “Eject” key for the CD/DVD drive, I remapped the “Eject” key to the “Delete” function.

Also the “Plusminus” and “Asciitilde” keys are swapped. The “Asciitilde” key is the short cut for $HOME, so I swapped this keys, too.

This is done automatically with a small shell script after logon. You need xmodmap and the right keycodes for that.

xmodmap -e "keycode 94 = grave asciitilde grave asciitilde dead_grave dead_horn"
xmodmap -e "keycode 49 = section plusminus section plusminus section plusminus"
xmodmap -e "keycode 169 = Delete"
This website uses cookies. By using the website, you agree with storing cookies on your computer. If you do not agree leave the website.More information about cookies
blog/start.txt · Last modified: 2017-09-02 23:37 by Tom, DL7BJ