Interview Question: Disk Space Monitoring Approach

The Question

“Write a bash shell script which will check the storage and if it is more than 70% will alert. It doesn’t have to be working or perfect; I want to know how you approach it or how the template should look like.”

My Approach

When approaching this problem, I would:

1. First identify the key requirements:
   • Need to check disk storage usage
   • Compare against a 70% threshold
   • Generate an alert if threshold is exceeded
2. Determine the bash commands needed:
   • df command to get disk usage information
   • Parsing tools like grep, awk to extract percentages
   • Conditional logic to compare against threshold
3. Create a script structure:

#!/bin/bash

# Script to check disk usage and alert if over threshold
# Set threshold percentage
THRESHOLD=70

# Get disk usage percentage for root filesystem (/)
USAGE=$(df -h / | grep -v Filesystem | awk '{print $5}' | tr -d '%')

# Check if usage exceeds threshold
if [ "$USAGE" -gt "$THRESHOLD" ]; then
    echo "ALERT: Disk usage is at $USAGE%, which exceeds threshold of $THRESHOLD%"
    # Here you could add additional alert methods:
    # - Send email
    # - Log to a file
    # - Trigger system notification
    # - Call webhook for monitoring system
else
    echo "Disk usage is at $USAGE%, below threshold of $THRESHOLD%"
fi

This script:

  1. Sets a threshold value (70%)
  2. Uses df command to get disk usage information
  3. Extracts just the percentage using grep and awk
  4. Removes the % sign
  5. Compares the usage against the threshold
  6. Outputs an alert message if threshold is exceeded

1. Mention potential improvements:
   • The script could be enhanced to check multiple filesystems
   • Could add flexibility with command-line arguments
   • Could implement different notification methods
   • Add logging capabilities
   • Set up as a cron job for regular monitoring