Watch Logfiles

Watch a text file as it grows:

tail -f logfile.txt

Print out iso date format

date --iso-8601=minutes

produces for example 2016-10-21T19:53+02:00

Run ssh-agent in remote login

When you log into a machine with SSH and want to use a SSH key to do further stuff, like managing a remote git repository, you may have to

eval $(ssh-agent -s)
ssh-add ~/.ssh/your_ssh_id

according to this site. Then the shell remembers your SSH key as long as it is open.