Alert on a disk filling up
Logs or backup files eat /var; in 24 hours the server falls over. A basic df check every 10 minutes saves a 2 AM incident.
Recipe
bash
#!/usr/bin/env bash
# /etc/cron.d/disk-watch — */10 * * * * root /opt/disk-watch.sh
THRESHOLD=${THRESHOLD:-85}
while read -r FS USED MOUNT; do
USED=${USED%\%}
if [ "$USED" -ge "$THRESHOLD" ]; then
curl -X POST "$SLACK_WEBHOOK" \
--data "{\"text\":\"$(hostname): $MOUNT at ${USED}% (was ≥ $THRESHOLD)\"}"
fi
done < <(df -P -x tmpfs -x devtmpfs | awk 'NR>1 {print $1, $5, $6}')Same thing in Enterno.io
The cron job itself should ping an Enterno heartbeat — if your script silently dies before checking the disk, Enterno still alerts because the ping never arrived.
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