change jvm options

sudo vi jvm.options

Elastic search start stop

Start
sudo service elasticsearch start
Stop
sudo service elasticsearch stop

show process memory usage ubuntu

ps aux --sort=-%mem | awk 'NR<=10{print $0}'

remove (delete) folder and its coontent in ubuntu terminal

sudo rm -r

copy content of folder to another folder

see what owner of files is (for sake).

sudo cp -a /source/. /dest/

this should copy all files and in my case assign right owner.
If not cd to the dest folder and use

sudo chown www-data:www-data *

Nginx test && reload

sudo nginx -t && sudo nginx -s reload

Install updates on ubuntu cmd

sudo apt-get update && sudo apt-get upgrade