anacron Explained: Run Missed Jobs After Downtime on Linux
How anacron runs daily, weekly and monthly jobs that cron missed while a machine was off: anacrontab syntax, cron.daily, delays, testing, and systemd timers.
Blog
Linux
Linux server administration: Debian, Ubuntu, AlmaLinux, storage, performance and troubleshooting.
htop Guide: Monitor Processes Interactively on Linux
Install and use htop: read CPU and memory meters, sort and filter processes, tree view, kill and renice, and spot common server problems.
Crontab Guide: Schedule Tasks on Linux with Cron
Schedule jobs with cron: crontab syntax, editing user and system crontabs, environment and PATH pitfalls, logging output, preventing overlaps and debugging.
GRUB Bootloader on Linux: Default Kernel, Boot Options, Repair
Configure GRUB2: /etc/default/grub, update-grub vs grub2-mkconfig, the default kernel, kernel parameters, showing the menu, and reinstalling GRUB.
Linux Capabilities: Run Services Without Full Root (setcap)
Grant programs only the privileges they need: CAP_NET_BIND_SERVICE for low ports, getcap and setcap, systemd AmbientCapabilities, and Docker cap_drop.
Shebang and Running Scripts on Linux: chmod +x, ./ and PATH
How Linux runs scripts: the shebang line, #!/bin/bash vs env, making scripts executable, ./script vs bash vs source, and fixing common errors.
scp Command: Copy Files Over SSH (With Examples)
Copy files and directories between your computer and a Linux server with scp: syntax, ports, keys, recursive and server-to-server copies.
Linux Wildcards and Globbing: *, ?, [ ], { } Explained
Shell wildcards on Linux: *, ?, character classes, brace expansion, recursive ** globs, dotglob and nullglob, quoting, and safe patterns for rm, mv and cp.
Snap Packages on Ubuntu: Install, Update, Remove or Disable Snap
Use snap on Ubuntu servers: install and manage snaps, channels, refresh schedules, disk usage of old revisions, snap vs apt, and removing snapd completely.
Zip and Unzip Files on Linux: Commands and Examples
Create and extract zip archives on Linux: zip folders, exclude files, passwords, list and test archives, unzip to a directory, large files.
dmesg Command: Read Kernel Messages (OOM, Disk, Network Errors)
Use dmesg to read kernel messages with readable timestamps, follow them live, filter by level, and spot OOM kills, disk I/O errors and segfaults.
add-apt-repository and PPAs on Ubuntu: Add, Use and Remove
Add PPAs and third-party apt repositories safely: add-apt-repository, signed-by keyrings instead of apt-key, deb822 .sources files, pinning and removal.
dpkg Command: Install, List and Fix .deb Packages (Ubuntu)
Use dpkg to install .deb files, list installed packages, find which package owns a file, fix "dpkg was interrupted" and broken installs, and hold packages.
Disk Full on Linux: "No Space Left on Device" Emergency Guide
Fix a full Linux disk step by step: find what is using space, free it safely, handle deleted-open files and inode exhaustion, then stop it happening again.
systemd Targets vs Runlevels: multi-user, rescue and Defaults
How systemd targets replace runlevels: list and switch targets, set the default, boot into rescue or emergency mode, and how services attach.
Bash Variables: Assignment, Quoting, Defaults and Arrays
Bash variables explained: assignment rules, quoting, command substitution, default values, string manipulation, arithmetic, arrays, scope and environment.
Linux history Command: Search, Reuse and Configure Bash History
Use Bash history: search with Ctrl+R, rerun commands with !!, !n and !$, add timestamps, save across sessions and remove sensitive entries.
AppArmor Basics on Ubuntu: Profiles, Complain Mode, Denials
AppArmor on Ubuntu and Debian: check status, read DENIED log lines, use complain mode, and allow custom paths for MySQL with local overrides.
cp Command in Linux: Copy Files and Directories (Examples)
Copy files and directories with cp: recursive copies, preserving permissions and timestamps, avoiding overwrites, symlinks, and when to use rsync.
rm Command in Linux: Delete Files and Directories Safely
Delete files and directories with rm: -r, -f and -i explained, safe habits, removing odd filenames, find -delete, recovering space held by deleted files.
No Space Left on Device but Disk Not Full? Fix Inode Usage
Fix No space left on device when df shows free space: check inodes with df -i, find directories with millions of small files, clean up, prevent it.
Bash for Loop: Syntax and Practical Examples
Write Bash for loops over lists, files, ranges and command output, use C-style loops, read lines safely with while read, and avoid quoting mistakes.
Cron Expression Examples: 40 Schedules Ready to Copy
Copy-ready cron expressions: every minute, every 5 minutes, hourly, daily at a time, weekdays, monthly, last day of month, plus ranges, steps and gotchas.
echo Command in Linux: Print Text and Variables (Examples)
Print text and variables with echo: quoting rules, -n and -e, escape sequences, writing to files, colours, and why printf is often better in scripts.