LIOS Logs

logger writes a message into the system log from the shell or a script — the proper way to make your own scripts log like any other service. Rather than scattering echo into ad-hoc files, logger hands your message to syslog/journald, so it lands in the same place as everything el...

Quiz: LIOS / Logs, Processes and Services | updated: Jul 14, 2026

32 bits, written as four dotted decimal octets (0–255 each), split into a network portion and a host portion. * One IPv4 address in dotted-decimal and binary — the 32 bits split into four octets. — Michel Bakni, CC BY-SA 4.0, via Wikimedia Commons. * An IPv4 address is just a 32...

Quiz: LIOS / Network Configuration | updated: Jul 14, 2026

NetworkManager is the daemon that owns network config; nmcli is its command-line client, structured as nmcli <object> <command> over connections and devices. * NetworkManager separates connections (saved profiles) from devices (the NIC) — a device can hold several profiles but o...

Quiz: LIOS / Network Configuration | updated: Jul 14, 2026

Set the hostname with hostnamectl set-hostname; name resolution is governed by /etc/hosts (local overrides), /etc/resolv.conf (DNS servers), and /etc/nsswitch.conf (lookup order). Two related but separate things: the machine's own name, and how it resolves other names. hostnamect...

Quiz: LIOS / Network Configuration | updated: Jul 14, 2026

semanage fcontext records the PERMANENT rule for what a path's context should be, restorecon resets a file to that policy-defined context, and chcon slaps on a TEMPORARY context that the next relabel will undo. * semanage fcontext (rule) vs restorecon (apply) vs chcon (temporary...

Quiz: LIOS / SELinux Security | updated: Jul 14, 2026

Root is UID 0, the superuser the kernel exempts from every permission check; you avoid logging in as root because one mistake (or one compromised command) then has unlimited, unlogged reach. The deeper reason is the principle of least privilege: you want to operate with only the...

Quiz: LIOS / User Management and Permissions | updated: Jul 14, 2026

-R walks a directory tree and applies the change to everything inside; bare operators like +x / -w / =r default to "all" (same as a+x) when you omit the who. A real trap with recursive numeric modes: chmod -R 755 forces the execute bit onto files too, not just directories. Often...

Quiz: LIOS / User Management and Permissions | updated: Jul 14, 2026

top is an interactive, continuously-refreshing process monitor — a live view of CPU, memory, load, and the busiest processes. Where ps is a single snapshot, top updates every couple of seconds, so it's what you open to catch what's happening right now — which process is pegging t...

Quiz: LIOS / Logs, Processes and Services | updated: Jul 14, 2026

A subnet is a set of hosts that share the same network portion and can reach each other directly (Layer 2) without going through a router. The network/host split of an IP address is what defines a subnet: every host whose network portion matches is "local" to each other. Two host...

Quiz: LIOS / Network Configuration | updated: Jul 14, 2026

In three .nmconnection files dirs: /etc/... for your persistent profiles, /run/... for temporary ones, /usr/lib/... for vendor defaults. The same three-tier layout systemd uses applies here: admin config in /etc (persistent, the one you usually edit), runtime/transient state in /...

Quiz: LIOS / Network Configuration | updated: Jul 14, 2026