File operators:

Posgtesql cheat sheet, use with caution, most compatible with mysql

connect to db
\c db_name;

create database
create database db_name;
list databases
\l

Turn off adding spaces to newline when copy to vim

:set paste

revert with
:set nopaste

How to clean postgresql db without actually dropping it

connect to desired db
\c db_name

check db schema
\dn

delete tables
DROP SCHEMA public CASCADE;
CREATE SCHEMA public;

tar
tar -zcvf prog-1-jan-2005.tar.gz /home/jerry/prog

untar
$ tar -zxvf prog-1-jan-2005.tar.gz

openssl x509 -text -noout -in

Check mysql

SELECT table_name AS "Table", ROUND(((data_length + index_length) / 1024 / 1024), 2) AS "Size (MB)" FROM information_schema.TABLES WHERE table_schema = "DB_name" ORDER BY (data_length + index_length) DESC;

Update hostname in debian without restart

hostnamectl set-hostname hostname

Check for records
amavisd-new showkeys

Add a new one
amavisd-new genrsa /var/lib/dkim/new_domain.com.pem 1024