Progression sums

Arithmetic progression sum

S(n, p) = sum(i**p for i in range(1, n)) = Theta(n ** (p + 1)), where p >= 1

Geometric progression sum

G(n, a) = sum(a ** i for i in range(1, n)) = a * (a ** (n+1) - 1) / (a - 1)

If n -> Infinity

G(n, a) = 1 / (1 - r)

Check OpenSSH Roaming vulnerability

This command should complete with no output

ssh -v -T git@github.com 2>&1 | grep Roaming 

Change MySQL user password

set password for 'user'@'host' = PASSWORD('password')

Manage GnuPG keys

Create GnuPG key pair

gpg --gen-key

List keys

gpg --list-keys
gpg --list-public-keys
gpg --list-secret-keys

Export keys

gpg --armor --output <keyid>-public.key --export <keyid>
gpg --armor --output <keyid>-secret.key --export-secret-keys <keyid>

Import keys

gpg --import  <keyid>-public.key
gpg --import  <keyid>-secret.key

 Delete keys

gpg --delete-secret-keys <keyid>
gpg --delete-keys <keyid>

Add some packages from PPA

dh-virtualenv

add-apt-repository ppa:spotify-jyrki/dh-virtualenv

ansible

apt-get install software-properties-common
apt-add-repository ppa:ansible/ansible

Run Celery task from command line

Run Celery task from command line

celery call --app <app.module.path> <task.module.path> --args '["argument"]'

--args parameter should be valid JSON