Monitor disk space on Slackware with a Bash script

1. Goal

Warn when a partition exceeds a threshold (e.g. 85%) before the server gets stuck due to full disk.

2. Example Bash script

#!/usr/bin/env bash
set -euo pipefail

THRESHOLD=85
LOGFILE=/var/log/disk-check.log

df -P | awk 'NR>1 {print $5, $6}' | while read -r use mountp; do
  pct=${use%%%}
  if [ "$pct" -ge "$THRESHOLD" ]; then
    echo "$(date '+%F %T') WARN ${mountp} ${pct}%" >> "$LOGFILE"
  fi
done

Save for example as /usr/local/sbin/disk-check.sh and make it executable:

chmod +x /usr/local/sbin/disk-check.sh

3. Manual test

/usr/local/sbin/disk-check.sh
tail -n 50 /var/log/disk-check.log

4. Schedule with cron

chmod +x /etc/rc.d/rc.crond
/etc/rc.d/rc.crond start
crontab -e

# Check every 15 minutes
*/15 * * * * /usr/local/sbin/disk-check.sh

5. Possible improvements

• Email with mail/mailx
• Telegram/Discord webhook
• Exclude temporary mounts
• Check inodes with df -i

6. Useful checks

df -h
df -i
du -sh /var/log/* | sort -h | tail

Quick checklist

[ ] Script created and tested
[ ] rc.crond active
[ ] Cron configured
[ ] Log checked
[ ] Threshold appropriate for the server

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