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Linux

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20241

Linux23 Jul 2024Elasticsearch 8 and Kibana on Ubuntu: Secure Single-Node SetupInstall Elasticsearch and Kibana 8.14 from the Elastic apt repository with security on by default, enrol Kibana, set heap and system limits, index some data and take a snapshot.

Elasticsearch 8.14
Kibana 8.14
Ubuntu 22.04 LTS

20208

Linux27 Apr 2020Ubuntu 20.04 LTS Is Out: What ChangedWhat Ubuntu 20.04 LTS (Focal Fossa) brings for servers, what changed from 18.04, and a sensible plan for when and how to upgrade.

Ubuntu 20.04 LTS
Linux kernel 5.4
systemd 245

Linux6 Apr 2020Quality of Life: ~/.ssh/config and tmuxFaster, safer SSH with per-host config, jump hosts and multiplexing, and tmux sessions that survive disconnects.

Ubuntu 18.04.4 LTS
OpenSSH 7.6
tmux 2.6

Linux16 Mar 2020Debugging with strace, lsof and tcpdumpThree tools that show what a process really does: system calls, open files and network packets, with worked examples for common production mysteries.

Ubuntu 18.04.4 LTS
strace 4.21
lsof 4.89

Linux2 Mar 2020SELinux and AppArmor in Plain TermsHow mandatory access control adds a second layer behind file permissions, how to diagnose denials on CentOS and Ubuntu, and fix them without turning protection off.

CentOS 7.7
SELinux
Ubuntu 18.04.4 LTS

Linux17 Feb 2020Updates, Kernels and LivepatchA patching routine for Ubuntu servers: security updates, kernel and reboot handling, the HWE kernel, Livepatch, and how to roll back safely.

Ubuntu 18.04.4 LTS
Linux kernel 5.3 HWE
unattended-upgrades

Linux3 Feb 2020Performance Triage: Load, CPU, Memory and DiskA repeatable five-minute method for finding which resource is the bottleneck, using vmstat, iostat, sar and pidstat, plus how to read the numbers.

Ubuntu 18.04.3 LTS
sysstat 11.6
procps-ng 3.3.12

Linux20 Jan 2020LVM: Growing a Volume Without DowntimeHow physical volumes, volume groups and logical volumes fit together, and a safe runbook for extending a mounted filesystem when a disk is full.

Ubuntu 18.04.3 LTS
LVM2 2.02
ext4

Linux6 Jan 2020Python 2 Reaches End of LifeWhat the end of Python 2 means for servers and scripts, how to find every use of it, and a safe migration plan with testing and fallbacks.

Ubuntu 18.04.3 LTS
Python 3.6
CentOS 8.1

201916

Linux16 Dec 2019Backups with rsync and tarBuild a simple, restorable backup routine with tar and rsync: what to back up, how to rotate copies, how to verify them, and how to restore without surprises.

Ubuntu 18.04.3 LTS
rsync 3.1
GNU tar 1.29

Linux2 Dec 2019Host Firewalls: ufw and firewalldDefault-deny rules on Ubuntu with ufw and on CentOS with firewalld, safe rule testing over SSH, zones, rate limiting and how cloud security groups fit in.

Ubuntu 18.04.3 LTS
ufw 0.36
CentOS 7.7

Linux18 Nov 2019Logs: /var/log, journalctl and logrotateKnow where the important logs live, read them effectively, and configure rotation and retention so logs help you instead of filling the disk.

Ubuntu 18.04.3 LTS
rsyslog 8.32
logrotate 3.11

Linux4 Nov 2019Scheduling Jobs: cron and systemd TimersWrite reliable cron entries, understand why jobs that work in a terminal fail under cron, prevent overlapping runs, and compare cron with systemd timers.

Ubuntu 18.04.3 LTS
cron 3.0
systemd 237

Linux21 Oct 2019Shell Scripting BasicsVariables, conditions, loops, functions and exit codes, with the strict-mode header, quoting rules and logging pattern that make scripts safe to run on servers.

Ubuntu 18.04.3 LTS
bash 4.4
ShellCheck 0.4

Linux7 Oct 2019SSH Keys and a Safer sshdReplace passwords with keys, harden sshd_config safely without locking yourself out, restrict users, and add basic brute-force protection.

Ubuntu 18.04.3 LTS
OpenSSH 7.6
CentOS 7.7

Linux16 Sept 2019Networking Basics: ip, ss, dig and NetplanA layer-by-layer method for diagnosing connectivity: addresses, routes, listening ports and DNS, plus how to set a static IP on Ubuntu 18.04 and CentOS 7.

Ubuntu 18.04.3 LTS
Netplan
iproute2 4.15

Linux2 Sept 2019Managing Services with systemdStart, stop, enable and debug services, read their logs, write a hardened unit file with restart policy, and use drop-ins instead of editing vendor files.

Ubuntu 18.04.3 LTS
systemd 237
CentOS 7.6

Linux19 Aug 2019Disks and Mounts: lsblk, fdisk, mkfs and fstabAdd a new disk safely: identify it, partition, create ext4, mount it persistently by UUID, and avoid the fstab mistakes that stop a server booting.

Ubuntu 18.04.3 LTS
util-linux 2.31
ext4

Linux5 Aug 2019Text Processing: grep, sed, awk and PipesChain small tools to answer real questions about logs and configuration: count errors, find top clients, edit files safely and format reports.

Ubuntu 18.04.2 LTS
GNU grep 3.1
GNU sed 4.4

Linux15 Jul 2019Processes: ps, top and SignalsSee what is running, find what is consuming CPU and memory, understand process states, and stop processes in the right order using signals.

Ubuntu 18.04.2 LTS
procps-ng 3.3.12
CentOS 7.6

Linux1 Jul 2019Installing Software: apt on Ubuntu, yum on CentOSHow package managers, repositories and signatures work, the daily commands on both families, and how to add third-party repositories without weakening the system.

Ubuntu 18.04.2 LTS
apt 1.6
dpkg

Linux17 Jun 2019Reading and Setting File PermissionsWhat rwxr-xr-x really means, how chmod, chown and umask work together, and the special bits that explain odd permission problems.

Ubuntu 18.04.2 LTS
coreutils 8.28
CentOS 7.6

Linux3 Jun 2019Users, Groups and sudoCreate users and groups, grant exactly the access they need through sudo, lock accounts, and audit who can do what on Ubuntu and CentOS.

Ubuntu 18.04.2 LTS
sudo 1.8.21
CentOS 7.6

Linux20 May 2019Moving Around the Shell: ls, cd, find and FriendsThe commands that cover daily navigation, safe habits for deleting and copying, and the bash 4.4 shortcuts that save the most time.

Ubuntu 18.04.2 LTS
bash 4.4
GNU coreutils 8.28

Linux6 May 2019Where Things Live: The Linux Filesystem HierarchyA map of the directories on every Linux server, what belongs in each, how mounts fit in, and the commands that show you where space and files really are.

Ubuntu 18.04.2 LTS
Linux kernel 4.15
CentOS 7.6