linux-shell-scriptor

name	linux-shell-scriptor
description	Use when user wants to write, generate, or create a bash or shell script for any Linux task — backups, monitoring, deployment, automation, cron jobs, health checks, system maintenance, log rotation, or any described sysadmin use case.
version	1.4.0
author	Lehnert

Linux Shell Scriptor

Overview

Generates production-ready bash scripts from plain English descriptions. Every script follows Linux best practices: strict mode, structured error handling, timestamped logging, secure defaults, dry-run support, and a built-in usage function.

Language: Respond in the user's language. Script comments and variable names default to English.

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When to Use

• User describes any task they want automated as a shell script
• User says "write a bash script", "create a shell script", "script to…"
• Backup, monitoring, deployment, cleanup, health check, cron job, report, alerting
• User wants to automate any repetitive sysadmin or DevOps task

When NOT to Use

• User wants a Python / Perl / Ruby script → general coding
• User wants to audit an existing config → /linux-config-auditor
• User wants to configure a service → /linux-config-auditor
• User wants to set up cron scheduling only → /linux-cron-manager

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Clarification Protocol

If the user's description is missing critical details, ask one question at a time. Never ask more than two clarifying questions total before generating. Start generating and list assumptions if the use case is reasonably clear.

Missing info	Question to ask
Target distro	"Which Linux distro does this run on (Ubuntu, RHEL, Alpine…)?"
Run as which user	"Should the script run as root or a regular user?"
Triggered how	"Is this run manually, by cron, or triggered by another process?"
On failure behavior	"On failure, should it exit silently, log, or send a notification?"
Destructive actions	"Should there be a --dry-run mode to preview changes before applying?"

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Script Quality Standards

Every script MUST contain all of the following:

Element	Implementation
Shebang + strict mode	#!/usr/bin/env bash and set -euo pipefail
Script header	Name, version, purpose, date in a comment block
usage() function	Flags, arguments, examples, exit codes
Logging helpers	log(), warn(), error() functions writing to stderr with timestamps
Argument parsing	getopts or manual flag loop with validation and usage on bad args
Dependency check	command -v <tool> >/dev/null for every external command used
Trap + cleanup	trap cleanup EXIT to remove temp files and restore state; also trap 'error "Script interrupted"; cleanup; exit 130' INT TERM to handle kills
Idempotent logic	Safe to run multiple times wherever possible
Dry-run mode	--dry-run / -n flag for any script that modifies files or services
No hardcoded secrets	Credentials via env vars or config files only; never inline
Quoted variables	All variable expansions in double quotes: "$var"

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Templates by Use Case

Backup Script

• Defines SOURCE_DIR, DEST_DIR, RETENTION_DAYS
• Uses rsync -az --delete or tar -czf based on size
• Verifies backup integrity (checksum or restore test)
• Prunes old backups with find … -mtime +N -delete
• Lock file to prevent concurrent runs (flock)
• Logs start/end/size, emails or writes to syslog on failure

Monitoring / Health Check

• Checks disk usage (df), memory (free), CPU load (uptime), and key services (systemctl is-active)
• User-configurable thresholds (DISK_WARN=80, DISK_CRIT=90)
• Outputs OK / WARN / CRIT per check
• Optional Nagios-compatible exit codes (0/1/2)
• Can write to a status file for polling

Deployment Script

• Pull latest code (git pull or artifact fetch)
• Run build step if needed
• Run DB migrations
• Swap symlink or restart service
• On failure: rollback and log exactly what failed
• Appends to a deployment log with timestamp and git SHA

System Maintenance

• Package updates (apt/yum/dnf) with pre-check for reboot requirement
• Old file cleanup (find /tmp -mtime +7 -delete)
• Journal/log rotation trigger
• Creates a maintenance report in /var/log/maintenance.log

Log Management / Report

• Parses a log file with grep/awk/sed patterns provided by user
• Counts occurrences, extracts fields, detects anomalies
• Outputs a summary report to stdout or a file
• Optionally archives processed logs

Database Maintenance

• Connects using env vars (never hardcoded credentials)
• PostgreSQL: pg_dump, VACUUM, ANALYZE, pg_stat_activity monitoring
• MySQL: mysqldump, optimize tables, check binary log size
• Redis: redis-cli INFO, BGSAVE, key count / memory stats
• Sends result summary to log file; alerts on non-zero exit

TLS Certificate Expiry Monitoring

• Checks each domain with openssl s_client / openssl x509 -enddate
• Calculates days until expiry
• Sends email alert if expiry < 30 days (warning) or < 7 days (critical)
• Logs results; exits 0 on success, 1 on critical
• Can trigger certbot renew automatically if installed

Service Health Check with Auto-Recovery

• Uses systemctl is-active to check service status
• Restarts failed service once, waits 10s, checks again
• Sends alert if still down after restart attempt
• Logs all restart events with timestamp

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Security Rules

These are non-negotiable and must appear in every generated script:

• No eval with user input — ever
• Quote every variable expansion: "$var", "${array[@]}"
• Temp files via mktemp — never predictable paths like /tmp/script.tmp
• Validate file path inputs — check for .. traversal before using
• Restrictive umask for sensitive output: umask 077 before writing credentials or keys
• Avoid unnecessary sudo — document when privilege escalation is needed and why
• set -euo pipefail — always; prevents silent failures from masked errors

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Output Format

1. Write the script to ./scripts/<task-name>.sh
2. Also print the script in a fenced bash code block so the user can review it before running
3. Below the script, list any assumptions made (distro, user, paths, thresholds)
4. Show:

# Syntax check before first run
bash -n scripts/your-script.sh

# Make executable
chmod +x scripts/your-script.sh

# Test with dry-run (if script supports it)
./scripts/your-script.sh --dry-run

5. Suggest next steps based on script type

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Next Steps (always include after output)

Syntax check: bash -n scripts/your-script.sh ShellCheck: shellcheck scripts/your-script.sh (install: apt install shellcheck) If recurring: Add to cron with /linux-cron-manager or a systemd timer with /linux-systemd-manager If security-sensitive: Review the host with /linux-security-hardener If it reads config files: Audit those configs with /linux-config-auditor