# Shutdown
sudo shutdown -h now
# Reboot
sudo reboot
# See all users
cat /etc/passwd
# See all non-system users
cat /etc/passwd | grep /bin/bash
# Switch users
sudo su - <username>
# See disk space used (disk free) on all mounted partitions in human readable format:
df -h
# Or for a specific file system:
df -h /opt/finicity/
# Show block devices found on the machine (mounted or not) and any corresponding partitions it recognizes
lsblk
# List the human-readable sizes of a directory and any subdirectories, up to N levels deep
sudo du -ah -d 1 /home
# Kill process by ID:
kill -9 1234