Shell Script Overview

This is a shell script (written for /bin/sh, typically run on Linux) designed to run automated, basic health and performance diagnostics on a machine. It acts as an automated morning health checklist for system administrators or developers.

Breakdown of Script Actions

1. Header & Timestamp

• Prints a header title and logs the current system date and time using the date command.

2. Loopback Ping Test

• Pings 127.0.0.1 4 times (ping -c 4).
• Diverts standard output and error output to /dev/null to keep the console output clean.
• Checks $? (the exit code of the ping command). If 0 (success), it reports that loopback is reachable. This tests whether the system's internal network stack/adapter is functioning locally.

3. External Network Check

• Pings 1.1.1.1 (Cloudflare’s public DNS server) 4 times.
• Verifies if the machine has active internet/external network connectivity without relying on DNS resolution.

4. Disk Usage

• Runs df -h / to show available and used disk space on the root (/) filesystem in human-readable units (GB/MB).

5. System Load

• Runs uptime to display how long the server has been running, logged-in user counts, and system load averages over the last 1, 5, and 15 minutes.

6. Memory Usage

• Runs free -h to display total, used, free, and available RAM and Swap memory in human-readable units.

7. Process Snapshot

• Displays the top 5 CPU-consuming processes.
• Uses ps sorted by %cpu in descending order, then extracts the top 6 lines (1 header line + top 5 processes) using head -n 6.

8. Service Health Check

• Loops through a list of critical services (ssh and cron).
• Uses systemctl is-active --quiet <service> to check if the background service is running, printing ACTIVE or INACTIVE depending on the result.

How to Run It

1. Save the file as morning_check.sh.
2. Make it executable:

   chmod +x morning_check.sh

3. Execute it:

   ./morning_check.sh