📘 Running Scripts

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🎯 What You Will Learn

1. Understand interactive vs non-interactive script execution.
2. Learn to grant execution permission using chmod +x.
3. Execute Bash scripts safely in a VPS environment.
4. Automate WordPress tasks (backups, updates, database exports).
5. Send status notifications via Email (SMTP/Gmail) and Webhook (n8n/ActivePieces).
6. Apply logging, error handling, and scheduling (cron/systemd).

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🧭 5W + 1H Framework

Element	Description
What	Running a Bash script means executing a text file containing shell commands.
Why	Automates repetitive maintenance, reducing human error and saving time.
Who	System admins, DevOps engineers, or WordPress VPS owners.
Where	In an SSH terminal or automated context (cron, CI/CD pipeline).
When	For scheduled operations – backups, updates, or reports.
How	Create a .sh file, set execute permission (chmod +x), and run it interactively or through automation.

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⚙️ Prerequisites

• Familiarity with pwd, cd, ls.
• Access to a Linux VPS with sudo rights.
• Installed utilities: curl, jq, tar, mailx or msmtp.
• Optional cron enabled for non-interactive execution.

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Core Structure & Commands

1️⃣ Create a Basic Script

nano backup.sh

Content

#!/bin/bash
# WordPress backup example
echo "Starting backup..."
tar -czf /home/backup/wp_backup_$(date +%F).tar.gz /var/www/html
echo "Backup complete."

2️⃣ Make Executable and Run

chmod +x backup.sh
./backup.sh

Expected Output

Starting backup...
Backup complete.

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Interactive vs Non-Interactive

Mode	Command	Output	Use Case
Interactive	./backup.sh	Printed live	Manual execution
Non-Interactive	bash backup.sh or cron	Logged output	Automated tasks

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Adding Notifications

A. Send Email (Using Gmail or Your Own SMTP)

1️⃣ Install msmtp + mailx

sudo apt install msmtp msmtp-mta mailutils -y

2️⃣ Configure msmtp (SMTP Relay)

Edit /etc/msmtprc

defaults
auth            on
tls             on
tls_trust_file  /etc/ssl/certs/ca-certificates.crt
logfile         /var/log/msmtp.log

account default
host smtp.gmail.com
port 587
from [email protected]
user [email protected]
passwordeval "cat /root/.secrets/gmail_pass"

(For your own SMTP server, replace host, user, and from accordingly.)

3️⃣ Create Notification Script

#!/bin/bash
SUBJECT="[WP Backup] $(hostname) $(date +%F_%H%M)"
TO="[email protected]"
BODY="Backup completed successfully at $(date +%T)"

printf "Subject: %s\nTo: %s\n\n%s\n" "$SUBJECT" "$TO" "$BODY" | msmtp -t

Expected Output

# No terminal output on success
$ echo $?
0

Expected Log (/var/log/msmtp.log)

msmtp: host=smtp.gmail.com tls=on auth=on [email protected] recipients=1 sent

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B. Send Webhook (Using n8n / ActivePieces / Other 3rd Party)

1️⃣ Webhook Payload Example

#!/bin/bash
WEBHOOK_URL="https://n8n.yourdomain.com/webhook/wp_backup"
payload=$(jq -n \
  --arg host "$(hostname)" \
  --arg status "success" \
  --arg time "$(date --iso-8601=seconds)" \
  '{event:"backup_complete",host:$host,status:$status,time:$time}')

code=$(curl -sS -X POST "$WEBHOOK_URL" \
  -H "Content-Type: application/json" \
  -d "$payload" \
  -w "%{http_code}" -o /tmp/resp.json --max-time 10)

echo "Webhook response code: $code"
cat /tmp/resp.json

Expected Output

Webhook response code: 200
{"ack":"ok"}

2️⃣ Webhook Example for ActivePieces

WEBHOOK_URL="https://cloud.activepieces.com/api/v1/webhooks/abcdef123456"

Both platforms accept JSON POST; ActivePieces flows auto-parse keys (event, status, host).

C. Combine Backup + Email + Webhook

#!/bin/bash
set -euo pipefail
SITE_PATH="/var/www/html"
ARCHIVE="/home/backup/wp_backup_$(date +%F_%H%M).tar.gz"
EMAIL_TO="[email protected]"
WEBHOOK_URL="https://n8n.yourdomain.com/webhook/wp_backup"

echo "Starting backup..."
tar -czf "$ARCHIVE" "$SITE_PATH"
echo "Backup complete: $ARCHIVE"

# Send Email
SUBJECT="[WP Backup OK] $(hostname)"
BODY="Backup successful for $(hostname) at $(date)\nFile: $ARCHIVE"
printf "Subject: %s\nTo: %s\n\n%s\n" "$SUBJECT" "$EMAIL_TO" "$BODY" | msmtp -t

# Send Webhook
payload=$(jq -n --arg host "$(hostname)" --arg file "$ARCHIVE" --arg status "success" '{event:"backup_ok",host:$host,file:$file,status:$status}')
curl -sS -X POST "$WEBHOOK_URL" -H "Content-Type: application/json" -d "$payload" --max-time 10 -w "%{http_code}\n"

Expected Output

Starting backup...
Backup complete: /home/backup/wp_backup_2025-10-06_1410.tar.gz
200

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🧾 Scheduling (Non-Interactive Execution)

Add to cron:

0 2 * * * /home/user/scripts/wp_backup.sh >> /var/log/wp_backup.log 2>&1

Runs every day at 2 AM and logs to file.

Best Practices

Practice	Explanation
Use #!/bin/bash shebang	Ensures execution under Bash interpreter.
Absolute paths in cron	Avoids PATH mismatch issues.
Log stdout and stderr	Use >> /var/log/task.log 2>&1.
Secure SMTP passwords	Store in root-only file and use passwordeval.
Use timeouts on curl	Prevents hangs from down services.

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Static vs Dynamic Framing

Context	Static (Manual)	Dynamic (Auto)
Trigger	User runs script	Cron or remote event
Output	Live terminal	Logged file + notifications
Use case	Testing, troubleshooting	Production automation

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Troubleshooting Matrix

Issue	Cause	Solution
Permission denied	Script not executable	chmod +x script.sh
command not found	Missing shebang or path	Add #!/bin/bash, use full paths
Email not sent	msmtp not configured	Verify /etc/msmtprc and log
Webhook fails	Wrong URL or SSL issue	Check endpoint, add --insecure for testing
Cron runs but no mail / webhook	Missing absolute paths	Use /usr/bin/msmtp, /usr/bin/curl explicitly

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Quick Lab – WP Update Notifier

#!/bin/bash
set -e
WP_PATH="/var/www/html"
EMAIL="[email protected]"
WEBHOOK_URL="https://cloud.activepieces.com/api/v1/webhooks/xyz123"

wp plugin update --all --path=$WP_PATH
wp theme update --all --path=$WP_PATH
wp core update --path=$WP_PATH

printf "Subject: [WP Update] $(hostname)\nTo: %s\n\nPlugins/themes/core updated on $(hostname)\n" "$EMAIL" | msmtp -t

payload=$(jq -n --arg host "$(hostname)" --arg event "wp_update_ok" '{host:$host,event:$event}')
curl -sS -X POST "$WEBHOOK_URL" -H "Content-Type: application/json" -d "$payload" -w "%{http_code}\n"

Expected

200

Both email and webhook confirm success.

Cheat Sheet

Task	Command
Make script executable	chmod +x file.sh
Run interactively	./file.sh
Send email via msmtp	`printf "Subject: S\nTo: you@x\n\nBody\n"
Send JSON to webhook	curl -X POST -H "Content-Type: application/json" -d '{"key":"val"}' $URL
Check HTTP code	curl -w "%{http_code}" -o resp.json -sS
Log output	>> /var/log/file.log 2>&1
Cron edit	crontab -e

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Mini-Quiz

#	Question	Answer
1	Which command adds execute permission to a script?	chmod +x filename.sh
2	What interpreter line must be at the top of a Bash script?	#!/bin/bash
3	Which tool sends email using SMTP/Gmail?	msmtp
4	Which command sends JSON data to n8n or ActivePieces?	curl -X POST -H "Content-Type: application/json"
5	Why use absolute paths in cron jobs?	Cron uses limited environment PATH variables.

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