Foundations
Bash helps automate repetitive DevOps tasks quickly.
On this page
Use this page for fast recall. Use Full documentation when you want the complete end-to-end path.
A simple 5-step flow you can follow when using Bash in real work.
1) Setup
Install/run the tool and confirm version. Create a minimal config.
2) Small change
Do one small action end-to-end to prove the workflow.
3) Validate
Check output, logs, and status. Catch mistakes early.
4) Automate
Convert it into a repeatable script or pipeline step.
5) Productionize
Add safety: secrets, rollback, observability, and docs.
These are practical sequences you can copy into your own checklist or runbook.
Goal: Create a script you can trust in production-like tasks.
- Start by writing the manual steps as comments.
- Add checks (required env vars, command existence).
- Add `set -euo pipefail` and clear error messages.
- Log what you do (`echo` or `logger`) and capture outputs.
- Test on a throwaway environment, then version-control it.
- Variables
- Conditionals
- Loops
Learning path (high-level):
- Script basics
- Input/output handling
- Automation scripts
Create script
Command
touch script.sh && chmod +x script.shRun script
Command
./script.shDebug script
Command
bash -x script.shShort descriptions and practical intent. Search, filter, copy, and reuse.
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set -euo pipefailSafer scripts: fail fast + catch unset vars.
echo "$VAR"Print variable value (quote to preserve spaces).
export VAR=valueSet environment variable.
VAR=${VAR:-default}Default a variable if unset/empty.
if [ -f file ]; then echo ok; fiRun logic when file exists.
if command -v rg >/dev/null; then ...; fiCheck if a command exists.
for i in *; do echo "$i"; doneLoop over files.
while read -r line; do ...; done < fileRead file line by line.
command1 | command2Pipe output into another command.
cmd > out.txt 2>&1Redirect stdout+stderr to a file.
cmd | tee out.txtSee output and save it.
grep -n "text" fileSearch text with line numbers.
awk '{print $1}' fileExtract columns quickly.
jq '.items[] | .name' file.jsonParse JSON on CLI.
chmod +x script.shMake script executable.
Small blocks you can drop into your terminal, config, or runbook.
Safe script skeleton
bash
#!/usr/bin/env bash
set -euo pipefail
# usage: ./script.sh <arg>
ARG=${1:-}
if [ -z "$ARG" ]; then
echo "missing arg" >&2
exit 1
fi
echo "ok: $ARG"When things break, follow this order to stay calm and move fast.
- If a script behaves strangely: run with `bash -x script.sh` and add `set -x` temporarily.
- If pipes hide errors: use `set -o pipefail`.
- If whitespace breaks variables: quote expansions like "$VAR".
The common mistakes that slow people down when using Bash.
- Copy-pasting commands without understanding inputs/outputs and side effects.
- Not documenting defaults (ports, paths, credentials) and then getting stuck in prod.
- Skipping logs and metrics when troubleshooting; always collect evidence first.
Do these tasks in order. You will feel the tool instead of just reading about it.
- Install or run the tool locally (or in Docker) and verify it works with a hello-world action.
- Create a minimal config and run the most common command 3 times (with a small change each time).
- Break something on purpose and document how you debugged it in your Notes.
Use these to test if you truly understand the basics (and can explain them clearly).
- Explain the tool’s role in a real CI/CD pipeline from commit to production.
- Describe the most common failure you’ve seen with this tool and how you fixed it.
- What would you monitor/alert on for this tool in production?