Linux Server / Boot, systemd & Service Recovery
Compare a boot failure with the kernel actually running
A patch can install a new kernel without the server booting it, or a rollback can leave mixed expectations. Record both release and boot evidence.
Environment and inputs: Linux server baseline · Ubuntu 24.04 LTS / RHEL 9-style systems. Use the specified distribution, init system and installed tool; service names, privileges and supported options can differ.
Start with this check
Confirm the host, shell and access role. Replace sample names, paths, domains and interfaces with approved targets. These are diagnostic commands; assess policy and workload impact before making changes.
uname -r
journalctl --list-bootsRead the result
The first command identifies the running kernel; the second lists retained journal boots on a systemd host. Installed packages are a separate inventory.
Resolve and verify
Compare the selected boot entry, installed kernel packages and previous boot logs. Use the distro's supported rollback or boot-repair plan after identifying the failure.
Before changing production
Do not remove the last known working kernel or change bootloader defaults without a console and recovery path.