🐧 Linux Admin
Common Issues in Linux Administration — Part 1
Disk space, CPU/memory, network connectivity, service failures, and file permissions
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Common Issues in Linux Administration — Part 1. The five most frequent problems encountered in production Linux environments.
1. Disk Space Full Error: "No space left on device." → df -h, du -sh /var/log, clean old logs/cores
2. High CPU/Memory Usage System slow, OOM kills → top, ps aux --sort=-%mem, kill runaway process
3. Network Connectivity Issues "Host unreachable" or DNS failures → ping, dig, ip addr show, restart NetworkManager
4. Service Startup Failures "Failed to start service." → systemctl status <svc>, journalctl -xeu <svc>
5. File Permission Problems "Permission denied." → ls -la, chmod, chown, getenforce (SELinux)
🐧 Linux Admin
Common Issues in Linux Administration — Part 2
User auth, package errors, kernel panics, SELinux denials, and time sync issues
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Common Issues in Linux Administration — Part 2. Issues 6–10: auth failures, package errors, kernel panics, SELinux denials, and NTP sync problems.
6. User Authentication Issues SSH failure, "Access denied" → passwd, usermod -s /bin/bash, check /var/log/secure
7. Package Management Errors Broken deps, missing repos → apt update && apt upgrade, yum clean all && yum update
8. Kernel Panics / System Freezes Check /var/log/kern.log, update kernel, disable faulty modules
9. SELinux/AppArmor Denials Service won't start → audit2why < /var/log/audit/audit.log, audit2allow, adjust policy
10. Time Synchronisation Issues Kerberos/SSL failures, logs out of order → timedatectl, systemctl restart chronyd