Rsync --exclude

rsync -av . --exclude=.git /home/folder/Downloads

SSH Key - Still asking for password and passphrase

Add Identity without Keychain

There may be times in which you don't want the passphrase stored in the keychain, but don't want to have to enter the passphrase over and over again.
You can do that like this:

ssh-add ~/.ssh/id_rsa 

This will ask you for the passphrase, enter it and it will not ask again until you restart.

Add Identity Using Keychain

As @dennis points out in the comments, to persist the passphrase through restarts by storing it in your keychain, you can use the -K option (-k for Ubuntu) when adding the identity like this:

ssh-add -K ~/.ssh/id_rsa

Once again, this will ask you for the passphrase, enter it and this time it will never ask again for this identity.

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