FreeBSD 12 – devd event handler not firing for hotplug devices – Fix & Prevention

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

USB/network hotplug automation scripts do not execute, requiring manual intervention.

Environment & Reproduction

Happens after custom devd.conf edits or permissions changes.

service devd status
cat /etc/devd.conf
service devd restart

Root Cause Analysis

Malformed devd rule syntax or wrong match criteria prevents event action execution.

Quick Triage

Check daemon health and recent event stream output.

service devd onestatus
pgrep devd
tail -n 80 /var/log/messages

Step-by-Step Diagnosis

Run devd in debug mode and verify rule matching during device attach.

service devd stop
/usr/sbin/devd -d -f /etc/devd.conf
dmesg | tail -n 60

Solution – Primary Fix

Correct rule syntax and restart devd with validated config.

cp -a /etc/devd.conf /etc/devd.conf.bak
vi /etc/devd.conf
service devd start

Solution – Alternative Approaches

Move custom actions to dedicated include file under /usr/local/etc/devd for cleaner upgrades.

mkdir -p /usr/local/etc/devd
cat > /usr/local/etc/devd/custom.conf <<'EOF'
# custom rules
EOF

Verification & Acceptance Criteria

Hotplug event triggers expected command and logs confirm handler execution.

tail -f /var/log/messages
service devd restart

Rollback Plan

Restore prior devd.conf if new rule set suppresses other event handlers.

cp -a /etc/devd.conf.bak /etc/devd.conf
service devd restart

Prevention & Hardening

Lint custom devd rules and test with controlled hardware events.

service devd onestatus
cksum /etc/devd.conf

Related Errors & Cross-Refs

Related to rc.d service ordering issues and permission errors in invoked scripts.

Related tutorial: View the step-by-step tutorial for FreeBSD 12.

View all FreeBSD 12 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

FreeBSD devd daemon and event rule documentation.