To create variable.
export DB_USERNAME=dbuser
export DB_PASSWORD=secretpwdvalue
export DB_NAME=mydb
printenv | grep DB
echo $DB_NAME "IF YOU WANT TO SEE"
export DB_NAME=NEW-DB-NAME "To change new name"
if you want to do it permanently you have to use "Vim"
vim .bashrc
"at the bottem"
export DB_USERNAME=dbuser
export DB_PASSWORD=secretpwdvalue
export DB_NAME=mydb
esc
:qw
source .bashrc
printenv | grep DB
"if you want to do it for all users"
vim /etc/environment
Path