Get disk space on Linux and send notification to Slack channel via webhook if above threshold.

monitor-space.sh

#!/bin/bash

# get disk space available and report to Slack if below threshold
SLACK_WEBHOOK_URL=https://hooks.slack.com/services/TXXXXXXXXX/XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
DISK_THRESHOLD=60

DISK_USAGE=$(df -h / | awk '{ print $5 }' | tail -n 1 | sed 's/%//g')

if [ $DISK_USAGE -ge $DISK_THRESHOLD ]; then
    echo "Disk usage is $DISK_USAGE% - sending notification to slack"
    curl -X POST -H 'Content-type: application/json' --data '{"text":":exclamation: Disk space on Database Server ('$HOSTNAME') is high: *'$DISK_USAGE'%*"}' $SLACK_WEBHOOK_URL
else
    echo "Disk usage is $DISK_USAGE% - no notification sent"
fi

exit 0

Use cron (crontab -e) to run every minute: */1 * * * * /path/to/monitor-space.sh