The Bash Scripting Playbook
The Anatomy of a Production Script
Every production bash script follows the same skeleton. Here's the template that senior engineers use as a starting point:
#!/bin/bashset -euo pipefail# Exit on error, undefined vars, pipe failsTARGET_DIR="/var/backups"# Variables at the topLOG_FILE="/var/log/backup.log"mkdir -p "$TARGET_DIR"# Idempotent setupfor f in *.log; do# Process files cp "$f" "$TARGET_DIR/"doneecho "Done at $(date)"# Always log completion
🛡️ Best Practices
set -e— Exit on any errorset -u— Error on undefined variables- Always quote
"$variables" - Use
UPPER_CASEfor constants - Add echo statements for logging
⏰ Cron Cheat Sheet
* * * * *— Every minute*/5 * * * *— Every 5 minutes0 2 * * *— Daily at 2:00 AM0 0 * * 0— Weekly (Sunday midnight)0 0 1 * *— Monthly (1st at midnight)
⚠️ Common Bash Gotchas
- ❌
VAR = value→ spaces cause "command not found". UseVAR=value - ❌
if[$x == $y]→ missing spaces. Useif [ "$x" == "$y" ] - ❌ Unquoted
$varwith spaces → word splitting breaks paths - ❌ Missing shebang → script runs in wrong shell with wrong syntax
- ❌ Relative paths in cron → cron runs in minimal environment without $PATH
