linux-troubleshooting
Installation
SKILL.md
Troubleshooting
Distro support
Two-family skill. The diagnosis trees apply to both families; only service names, log paths, and a few tools differ — plus the RHEL family adds SELinux as a cause of failures that look like permission or connection bugs.
| When diagnosing… | Debian/Ubuntu | RHEL family |
|---|---|---|
| Web server unit | systemctl status apache2 |
systemctl status httpd |
| System log | /var/log/syslog, journalctl |
/var/log/messages, journalctl |
| Auth failures | /var/log/auth.log |
/var/log/secure |
| Web logs | /var/log/apache2/ |
/var/log/httpd/ |
| Firewall blocking a port | ufw status |
firewall-cmd --list-all |
| Package query | dpkg -l / apt |
rpm -qa / dnf |