3 Shell & command line
Every entry filed under Shell & command line and its subtopics.
What kind of help
Works on
What do these mean?
- Beginner
- You are new to this topic.
- Intermediate
- You use it, and want to get better.
- Advanced
- You know it well and need the details.
- Guided project
- Build something small from start to finish, step by step.
- Explains an idea
- Plain words on how something works and why.
- Step by step
- Numbered steps to get one task done.
- Cheat sheet
- Commands and options in a table, to look up fast.
- Fixes an error
- An error message, what it means, and how to solve it.
17 entries match these filters
- 0424 Cron-safe wrapper: lock, log and report failures for any scheduled command Wrap any cron or timer job so it never runs twice at once, writes a timestamped log, keeps the exit code and… Intermediate · Step by step · Linux Script cron & timers · Shell scripting 15 Oct 2026
- 0419 Quoting and word splitting in bash: why “$var” and arrays save you Single quotes, double quotes, no quotes and arrays: how bash splits words and expands globs, and the small set of habits that… Intermediate · Explains an idea · Linux, macOS Article Basics · Shell scripting 15 Oct 2026
- 0422 Dotfiles: keep your shell setup in git Put .bashrc, .zshrc, .gitconfig and your editor settings into a git repository so a new machine is set up in minutes: a… Intermediate · Step by step · Linux, macOS Article Modern command-line tools · Setup 15 Oct 2026
- 0421 grep, sed, awk and jq: the four text tools you will use every week A working reference for the four commands that handle most text on the command line: grep finds lines, sed edits them, awk… Intermediate · Cheat sheet · Linux, macOS Article jq & JSON on the command line · Modern command-line tools · Text processing 15 Oct 2026
- 0366 restic backup wrapper with tagging, retention and a weekly check A bash wrapper that runs restic backup on a fixed list of paths, applies a keep-daily/weekly/monthly policy with forget and prune, runs… Intermediate · Step by step · Linux, macOS Script Backup tools · Backups & syncing 15 Oct 2026
- 0346 The SSH config file: aliases, jump hosts and keys per server Reference for ~/.ssh/config: short names for servers, the right user, port and key per host, ProxyJump through a bastion, connection reuse and… Intermediate · Cheat sheet · Linux, macOS, Windows Article Keys & config · SSH 15 Oct 2026
- 0326 Fix: too many open files A process hit its file descriptor limit, usually 1024. Raise it for the shell, the systemd unit or the user, fix a… Intermediate · Fixes an error · Linux, macOS Article Performance & tuning · Processes & ports · Services & systemd 15 Oct 2026
- 0265 Turn a one-liner into a robust bash script: strict mode, options, logging, traps, locking and a schedule Grow a find-and-gzip one-liner step by step into a dependable bash script with strict mode, getopts, usage text, logging, error traps, dry-run,… Intermediate · Guided project · Linux, macOS Article Services & systemd · Shell scripting 15 Oct 2026
- 0254 Automate three servers with Ansible: roles, templates, Vault and safe dry runs Build a real Ansible project for two web servers and one database server: inventory groups, SSH keys, roles, templates, handlers, an encrypted… Intermediate · Guided project · Linux, macOS Article Ansible · Keys & config 15 Oct 2026
- 0186 Fix: Ansible UNREACHABLE! Failed to connect to the host via ssh Ansible could not open an SSH session to the host, so no task ran. The text after the colon tells you why:… Intermediate · Fixes an error · Linux, macOS Article Ansible · SSH & servers 15 Oct 2026
- 0109 A vzdump wrapper script with checks, retention and a log file A Bash wrapper around vzdump that checks the target storage first, backs up chosen guests or all guests with zstd and keep-last… Intermediate · Step by step · Linux Script Backup & restore · Shell scripting 15 Oct 2026
- 0108 List all Proxmox VE guests with status and locks (pvesh + jq) A Bash script that lists every VM and container in the cluster with node, status, lock, memory and uptime, using the Proxmox… Intermediate · Cheat sheet · Linux Script Shell scripting · VMs & containers 15 Oct 2026
- 0076 jq recipes: 23 one-liners for JSON on the command line A runnable collection of jq filters for everyday JSON work: pick fields, filter with select, reshape, sort, count, group, pass shell variables,… Intermediate · Cheat sheet · Linux, macOS, Windows Script Command-line tools · jq & JSON on the command line 15 Oct 2026
- 0054 Fix: Permission denied (publickey) The server refused every key your SSH client offered. Find out which key was offered, make sure its public half is on… Intermediate · Fixes an error · Linux, macOS, Windows Article Keys & config 15 Oct 2026
- 0052 Slice and summarize text with grep, sort, uniq, cut, awk and sed A handful of classic tools can filter, count, extract and rewrite text right in the terminal. This guide shows the patterns you… Intermediate · Step by step · Linux, macOS Article Finding files & text · Text processing 15 Oct 2026
- 0058 Safe bash script template with set ‑euo pipefail and trap A starting point for bash scripts that stops on errors, rejects unset variables, cleans up temp files on exit and parses options.… Intermediate · Cheat sheet · Linux, macOS Script Shell scripting 15 Oct 2026
- 0061 Fix: Address already in use (free a busy port) Your server cannot start because another process already listens on its port. This script shows which process holds the port and stops… Intermediate · Fixes an error · Linux, macOS Script Processes & ports · Shell scripting 15 Oct 2026