RHCSA
862 incident response problems that help with RHCSA prep.
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All problems (862)
LINUX-601A sudo rule allows the target subcommand (Permission Denied)A sudo rule allows the target subcommand (Permission Denied) focuses on linux-identity-and-access and asks the reader to isolate Permission Denied. 실무에서는 linux-identity-and-access 문제를 볼 때 서비스 로그만 보지 말고 inode, 파일시스템 여유, 포트 점유, systemd 상태, 최근 패키지 변경까지 같이 확인해야 원인을 빨리 좁힐 수 있습니다.LinuxIntermediate19 minProLINUX-186A writeback cache hides a failing SSD until metadata finally flips read-only and makes recovery much harder during a failover rehearsalPerformance stays good while risk quietly accumulates behind the cache layer. Normal traffic masked the issue until the standby or alternate path became active under rehearsal conditions.LinuxAdvanced19 minProLINUX-1210Cleanup removes the symlink target instead of the linkA production cleanup command copied from a forum answer follows the symlink and removes the target data instead.LinuxAdvanced19 minProLINUX-1219Firewall rules persist on disk but reboot restores an older iptables viewAn admin saves working firewall rules, reboots, and finds the old behavior back even though the config file never changed.LinuxAdvanced19 minProLINUX-095LVM thin pool reports plenty of virtual space but metadata exhaustion stops every writeThe logical volumes still look large enough, yet writes fail because the thin pool metadata area, not the data area, reached exhaustion first.LinuxAdvanced19 minProLINUX-105nftables accepts established flows but drops the related ICMP fragmentation signal so PMTU discovery never convergesNormal traffic starts, then large payloads stall because the firewall policy forgot a control message that is not part of the main flow tuple.LinuxAdvanced19 minProLINUX-1181systemd service restart loop starts after WorkingDirectory path was removedThe unit never gets far enough to expose the real app error because the configured WorkingDirectory no longer exists.LinuxIntermediate19 minProLINUX-691An application writes Unicode filenames correctlyAn application writes Unicode filenames correctly focuses on linux-performance-and-observability and asks the reader to isolate Rollout Stuck. 실무에서는 linux-performance-and-observability 문제를 볼 때 서비스 로그만 보지 말고 inode, 파일시스템 여유, 포트 점유, systemd 상태, 최근 패키지 변경까지 같이 확인해야 원인을 빨리 좁힐 수 있습니다.LinuxIntermediate20 minProLINUX-028Container host shows low CPU while one cgroup throttles hardContainer host shows low CPU (Resource Exhaustion) is a hands-on troubleshooting drill. Overall node utilization looks safe, but one service is heavily throttled because its cgroup limit is too low. Linux Service Operations needs to be checked by narrowing scope, recent change...LinuxIntermediate20 minProLINUX-1208EnvironmentFile is correct but a shell wrapper still overwrites the values before execThe unit file is fixed, yet the process launches with stale values because a later wrapper layer sources another profile.LinuxAdvanced20 minProLINUX-1213nftables rules load but container traffic still bypasses themA host nftables policy is restored at boot, but container startup later rewires the live path.LinuxAdvanced20 minProLINUX-1197Package install succeeds by hand but fails in automationA package repository fix from community posts made manual installs work. Automation still fails because the trust anchor update was not applied at the system scope.LinuxAdvanced20 minProLINUX-1186sudo rule looks correct but is ignoredA quick fix from community posts adds a sudoers include. The syntax looks fine, but the access rule never takes effect in production.LinuxAdvanced20 minProLINUX-1202Systemd service reads the right environment file but the binary still sees stale values from a wrapper scriptThe unit configuration looks correct, yet the process still starts with old settings because an extra wrapper script or sourced file overrides the expected environment later.LinuxAdvanced20 minProLINUX-1204Automated backup silently skips new filesA backup script copied from public examples worked before a layout change. It still exits successfully, but one new subtree remains permanently outside the backup set.LinuxAdvanced21 minProLINUX-1199Filesystem is writable but the service still failsA deployment path was moved following public hardening advice. The binaries or helper scripts now live under a mount point with noexec, and the service cannot start correctly.LinuxAdvanced21 minProLINUX-083LUKS volume unlock works manually but the early boot keyscript path is missing from initramfsThe passphrase and device are valid, yet unattended boot fails because the initramfs never included the helper needed to unlock the volume at the correct stage.LinuxAdvanced21 minProLINUX-1192Service starts manually but systemd failsA public troubleshooting pattern suggests testing the binary manually, and that succeeds. The unit still fails because the service user lacks access to one parent directory.LinuxAdvanced21 minProLINUX-022Systemd service restarts too quickly to capture useful logsA restart loop makes the service hard to inspect because the process dies before operators can capture the right signal.LinuxIntermediate21 minProLINUX-720A sudo rule allows the target subcommand (Permission Denied)A sudo rule allows the target subcommand (Permission Denied) focuses on linux-identity-and-access and asks the reader to isolate Permission Denied. 실무에서는 linux-identity-and-access 문제를 볼 때 서비스 로그만 보지 말고 inode, 파일시스템 여유, 포트 점유, systemd 상태, 최근 패키지 변경까지 같이 확인해야 원인을 빨리 좁힐 수 있습니다.LinuxIntermediate22 minPro