OS Fundamentals

Learning Objectives

• Understand core operating system components and their functions
• Learn to retrieve and interpret system information programmatically
• Develop skills in resource monitoring and analysis
• Implement process management techniques
• Create useful system reports for troubleshooting

Requirements

You are required to create a Bash script os-info.sh that gathers and displays detailed operating system information:

1. System Identification
   • OS distribution and version (/etc/os-release)
   • Kernel version (uname -r)
   • System architecture (uname -m)
   • Hostname and network identity (hostname, hostname -f)
2. Runtime Statistics
   • System uptime and load averages (uptime)
   • Current date and time (date)
   • Logged-in users (who)
   • Last login information (last | head -5)
3. Process Information
   • Total running processes (ps aux | wc -l)
   • Top 5 CPU-consuming processes (ps aux --sort=-%cpu | head -6)
   • Top 5 memory-consuming processes (ps aux --sort=-%mem | head -6)
   • Process tree of a specific service (pstree -p $(pidof sshd))
4. Memory Usage
   • Total and available memory (free -h)
   • Swap usage (swapon --show)
   • Key stats from /proc/meminfo
5. Storage Information
   • Disk usage by filesystem (df -h)
   • Disk usage by directory (du -sh /var /home /opt)
   • Inode usage (df -i)
6. Report Formatting
   • Clear section headers
   • Timestamp of report generation
   • Both detailed and summary views

Stretch Goals

• Add resource usage trends over time using a cron job
• Add CPU temperature monitoring (if available)
• Implement color-coded output based on usage thresholds
• Include network interface statistics

Deliverables

• os-info.sh script implementing all required sections
• Example output from a real execution
• Documentation explaining what each metric means and how to interpret it

References

• Linux Procfs Documentation
• Understanding Linux Load Averages
• Linux Performance Analysis in 60s - Netflix
• Guide to /proc filesystem
• Linux Memory: linuxatemyram.com

Once you complete this task you will know how to programmatically retrieve system information for monitoring and debugging - essential knowledge for operating any server in a DevOps environment.