Category: linux

How to set up NordVPN on Ubuntu

There are two ways to set up a VPN connection with NordVPN on Ubuntu. The first one is to add NordVPN’s package repository to the apt sources and then install the nordvpn client via a simple sudo apt install nordvpn. The second one is to install OpenVPN and configure it to use the servers of NordVPN.
This how-to was written for Ubuntu 18.04 LTS (Bionic Beaver).

Process Control in a Linux Shell

Working on the command line in a Linux shell can be tricky at times. A frequent source of frustration is that tasks which are trivial with a graphical desktop environment can be seemingly much more difficult to achieve on the command line. For example switching between multiple running applications only requires one or two mouse clicks on a graphical desktop, but demands more arcane knowledge to do it on the command line.

Upgrading Fedora

I have an old T61 notebook with Fedora 23. Since this distribution release is quite outdated I upgraded to the latest release version (27) this weekend. This can be done quite easily with the dnf-plugin-system-upgrade package.

$ sudo dnf install dnf-plugin-system-upgrade

$ sudo dnf system-upgrade download –refresh –releasever=27

$ sudo dnf system-upgrade reboot

If all goes well Fedora will upgrade to release 27 after the next reboot. I had to uninstall a few packages first, for which dnf complained about dependency conflicts.

For more details check out the Fedora Wiki.

Sneaky Serial Port

Tried out serial communication b/w PC (Windows 7 using hterm) and notebook (Fedora 23 using bash+stty).

Could get data from notebook to PC but not vice versa. Reading from /dev/ttyUSB0 just would not show any received data.

Tried out all combinations of parity bits, stop bits.

Turns out all data arrived but LF was missing, so nothing was displayed in the shell….

That’s one wasted afternoon.

Installing Altera Quartus Prime on Fedora 23

Installation did run without problems.
Executing >>quartus from the ~/altera/15.1/quartus/bin folder has no effect whatsoever, no error is printed on the command line.
Adding the above path to $PATH has no effect.
Running >>quartus 2> quartus.stderr to redirect stderr to a file uncovers the following error:

>>cat quartus.stderr
>quartus: error while loading shared libraries: libpng12.so.0: cannot open shared >object file: No such file or directory”

Aha, so a file is missing, why can’t quartus just tell me this?

>>sudo dnf search libpng12
>…
>libpng12.i686 : Old version of libpng, needed to run old binaries
>libpng12.x86_64 : Old version of libpng, needed to run old binaries
>libpng12-devel.i686 : Development files for libpng 1.2
>libpng12-devel.x86_64 : Development files for libpng12
>…

>>sudo dnf install libpng12
>…
>Complete!

Ok let’s try again…

>>quartus

Finally, it works.

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