grep
80+ tested grep examples: recursive search, regex flavours, context lines, counting, scripting, and more.
debian.tips
Practical Linux and Debian tips, tricks, and command references.
Start here
Pipes and redirection
How | connects commands together, and how >, >>, 2>&1, and <() route data to and from files, other commands, and each other.
Variables and quoting
Why unquoted variables break bash scripts, when to use double vs single quotes, and how glob characters make it worse.
Find the largest files on disk
Locate what's actually eating your disk space, from a whole filesystem down to one directory.
APT essentials
The apt, apt-get, and dpkg commands that cover almost everything you'll do to manage packages on Debian, and how remove differs from purge.
Commands
curl
80+ tested curl examples: GET/POST/PUT/DELETE, headers, auth, cookies, uploads, redirects, retries, and scripting.
find
Tested find examples: name and type filters, size and age, permissions, -exec vs -delete, and safe scripting patterns.
grep
80+ tested grep examples: recursive search, regex flavours, context lines, counting, scripting, and more.
sed
Tested sed examples: substitution, addressing, deletion, in-place editing, and multi-command scripts.
tar
Tested tar examples: create, list, and extract archives, choose a compression format, and verify integrity.
Concepts
Exit codes and error handling
How $?, PIPESTATUS, set -e, and pipefail combine to tell a script what actually succeeded or failed, and where each one falls short.
File permissions explained
The rwx/owner-group-other model, numeric vs symbolic chmod, umask, and why setuid/setgid on directories behave differently than you'd expect.
Pipes and redirection
How | connects commands together, and how >, >>, 2>&1, and <() route data to and from files, other commands, and each other.
Scripting
Your first script
Write, mark executable, and run your first bash script, plus what the shebang line and PATH lookup actually do.
Variables and quoting
Why unquoted variables break bash scripts, when to use double vs single quotes, and how glob characters make it worse.
Conditionals and test
The difference between [ and [[ in bash, why unquoted variables crash [ but not [[, and pattern matching with case.
Recipes
Bulk rename a batch of files
Rename many files at once with a plain bash loop, safely handling spaces and previewing changes before committing.
Copy files between two machines over SSH
Transfer a file or directory tree between two machines with scp or rsync, and resume an interrupted transfer without starting over.
Find the largest files on disk
Locate what's actually eating your disk space, from a whole filesystem down to one directory.
Find and kill whatever is using a port
Identify the process bound to a TCP port that's refusing to let a service start, then stop it.
Monitor a log file in real time
Watch a log file as new lines are written, filter it live, and keep watching across log rotation.