PATH

You can skip the step of manually loading the library by letting Linux do it for you when you log in automatically.

Run below commands

echo ". $HOME/my_functions.lib" >> ~/.bashrc
echo ". $HOME/my_functions.lib" >> ~/.bash_profile
source ~/.bashrc
source ~/.bash_profile
That's it. You can directly execute your function from the command line without doing anything.

Making multiple directories at once

echo "augustus" "september" "oktober" "november" | xargs -n 1 mkdir

No USB device available in Virtualbox

"Please add your user name to the 'vboxusers' group with this command:

sudo adduser [$USER] vboxusers

After that you must logout and login.
Please check this for more details:

https://help.ubuntu.com/community/VirtualBox/USB"

https://superuser.com/questions/956622/no-usb-devices-available-in-virtualbox

Copying the same file to two locations

Copying the same file to two locations by using the cp command twice still seems logical but let us suppose we have to copy the file to three, five, or even more locations. Here is how a single command can achieve this purpose.

Syntax:

$ echo [destination1] [desctination2] [destiantion3]..... | xargs -n 1 cp [/location/sourcefile]

https://vitux.com/copying-one-file-simultaneously-to-multiple-locations-through-ubuntu-command-line/

How to permanently set $PATH on Linux/Unix?

You need to add it to your ~/.profile or ~/.bashrc file.

export PATH="$PATH:/path/to/dir"
Depending on what you're doing, you also may want to symlink to binaries:

cd /usr/bin
sudo ln -s /path/to/binary binary-name
Note that this will not automatically update your path for the remainder of the session. To do this, you should run:

source ~/.profile
or
source ~/.bashrc

https://stackoverflow.com/questions/14637979/how-to-permanently-set-path-on-linux-unix

Latex structure

\documentclass{article}
\usepackage[utf8]{inputenc}

\title{Probeersel}
\author{cornelispeek }
\date{July 2018}

\begin{document}

\maketitle

\section{Introduction}
What shall we do \cite{berne} with

\bibliographystyle{plain}
\bibliography{boeken}
\end{document}

You have to name the bibliography file and bibliographystyle before \end{document}

Get a list of Open Ports in Linux

ss -lntu

-n, --numeric       don't resolve service names
-l, --listening     display listening sockets
-t, --tcp           display only TCP sockets
-u, --udp           display only UDP sockets