debian

apt

# /etc/apt/sources.list
deb http://deb.debian.org/debian stable main contrib non-free-firmware
deb http://security.debian.org/debian-security stable-security main contrib non-free-firmware
deb http://deb.debian.org/debian stable-updates main contrib non-free-firmware

APT

sudo apt rdepends {package}
sudo apt remove --simulate {package}

Fix broken installs:

sudo dpkg --configure -a
sudo apt -f install

systemd

Inspect boot process:

systemd-blame analyze

Managing services

# list services
systemctl list-unit-files --type=service

# filter by state
systemctl list-unit-files --type=service --state=enabled

# stops a service (starts again at next boot)
sudo systemctl stop service

# stops a service from starting at boot
# use `--now` option to stop service immediately
sudo systemctl disable service

# enables a service to start at next boot
# use `--now` option to start service immediately
sudo systemctl enable service

# starts a service
sudo systemctl start service

# masks a service, blocking it from being started
# use `--now` option to stop service immediately
sudo systemctl mask service

# reverse masking
# use `--now` option to start service immediately
sudo systemctl unmask service