- Explains the meaning of load average in htop: it's the exponentially damped moving average of the number of running and uninterruptible processes, not directly CPU usage percentage.
- Describes how to use tools like uptime, /proc files (e.g., /proc/uptime, /proc/loadavg), and strace to gather system information, including uptime and load averages.
- Details process states (R, S, D, Z, T, t), niceness/priority, memory usage metrics (VIRT, RES, SHR, MEM%), and how processes are managed via fork/exec/wait and signals.
- Covers user management, /etc/passwd and /etc/shadow files, sudo, setuid executables, and process ownership.
- Lists and explains common system processes on Ubuntu Server (e.g., systemd-journald, cron, sshd, rsyslogd), including how to remove unnecessary ones.