Tag: linux

Bash Process Substitution: What <() and >() Actually Do

Process substitution lets you treat a command's output as a file, and feed input to a command as if it were a file. It's weird but powerful.

Ulimit, Cgroups, and the Art of Stopping Processes From Eating Your Server

Control runaway processes with ulimit and cgroups v2: per-process limits, systemd resource controls, Docker cgroup integration, and practical examples to prevent one service from killing your server.

Here Documents vs Here Strings in Bash

<<EOF syntax for multiline input, <<-EOF for indentation, <<<string for single lines. When to use each.

GNU parallel for Embarrassingly Parallel Tasks

GNU parallel runs tasks in parallel across CPU cores. It's faster than xargs and easier than writing a job queue. Here's when and how to use it.

LVM Advanced: Snapshots, Thin Provisioning, and Not Losing Your Data

Master LVM snapshots and thin provisioning on Linux. Learn to create, use, and merge snapshots for backups, and over-provision storage safely.

SSH Hardening: Lock Down Remote Access Without Locking Yourself Out

Harden SSH properly: disable password auth, switch to Ed25519 keys, configure sshd_config, set up SSH certificates with step-ca, add 2FA, and configure ProxyJump for bastion hosts.

WireGuard Is Fast, But You're Leaving Performance on the Table

WireGuard performance tuning: MTU optimization, CPU offloading, AllowedIPs routing, PersistentKeepalive tradeoffs, and iperf3 benchmarking. Squeeze every MB/s from your VPN tunnel.

trap in Bash: Clean Up When Your Script Dies

trap EXIT for cleanup, trap INT/TERM for graceful shutdown, trap ERR for errors. Reliable error handling.

Debugging Bash Scripts: set -x and Beyond

set -x prints every command before it runs. Add PS4 for context. Use trap for cleanup. Here's the toolkit every bash debugger needs.

Word Splitting: The Bash Gotcha That Corrupts Filenames

Unquoted variables split on IFS, breaking loops and file operations. Always quote vars. Here's why.

String Manipulation in Bash (Without sed or awk)

Bash has built-in string operations: substring extraction, find-replace, case conversion, and trimming. You don't need sed for basic text work.

bash `set -e` Doesn't Work Like You Think

set -e silently fails in subshells, pipes, and conditionals. Learn the gotchas and fix them.