The issue you're describing suggests that you're trying to disable or mask the
[email protected] on a Linux system (likely using systemd), but after rebooting, the service remains active. This can happen due to misconfiguration, dependencies, or the service being re-enabled by the system. Below are steps to troubleshoot and resolve this issue.1. Understand the
[email protected] is a systemd service that provides a login prompt on the serial console (ttyS0). It is typically used for systems that require serial port access, but if you don't need it (e.g., no serial console is used), you can disable or mask it.2. Check the Current StatusFirst, verify the status of the service:bash
sudo systemctl status
[email protected]
Look for whether the service is active (running) or enabled.
Check the logs for any clues about why it might be starting:bash
journalctl -u
[email protected]
3. Disable the ServiceTo prevent the service from starting at boot, use the disable command:bash
sudo systemctl disable
[email protected]
This removes the service from the boot process but does not stop it if it's currently running.
Verify it’s disabled:bash
systemctl is-enabled
[email protected]
It should return disabled.
4. Stop the Service (Optional)If the service is currently running, stop it:bash
sudo systemctl stop
[email protected]
Confirm it’s stopped:bash
systemctl status
[email protected]
5. Mask the Service (Stronger Option)If disabling doesn’t work (e.g., another service or configuration re-enables it), you can mask the service to prevent it from starting:bash
sudo systemctl mask
[email protected]
Masking creates a symlink to /dev/null, making the service unrunnable.
Verify it’s masked:bash
systemctl is-enabled
[email protected]
It should return masked.
6. Check for DependenciesSometimes, other services or configurations (e.g., getty.target) may cause
[email protected] to start. Check for dependencies:bash
systemctl list-dependencies getty.target
Look for
[email protected] in the output.
If it’s listed, you may need to modify the configuration that’s pulling it in.
7. Inspect Kernel Command LineThe serial console might be enabled via the kernel command line. Check the kernel parameters:bash
cat /proc/cmdline
Look for parameters like console=ttyS0. If present, the kernel is configured to use the serial console, which may trigger the service.
To remove it, edit the GRUB configuration:Edit /etc/default/grub.
Find the line with GRUB_CMDLINE_LINUX and remove console=ttyS0 (or similar).
Update GRUB:bash
sudo update-grub
Reboot:bash
sudo reboot
8. Check for Systemd Generator or PresetSome systems use systemd generators or presets to automatically enable serial-getty services. Check:Systemd Presets:bash
cat /usr/lib/systemd/system-preset/*.preset
Look for lines enabling
[email protected]. If found, you can override this by creating a custom preset:bash
sudo mkdir -p /etc/systemd/system-preset
echo "disable
[email protected]" | sudo tee /etc/systemd/system-preset/99-custom.preset
Systemd Generators:
Check for custom generators in /lib/systemd/system-generators/ or /etc/systemd/system-generators/. If one is enabling the service, you may need to modify or remove it.
9. Verify After RebootAfter making changes, reboot the system:bash
sudo reboot
Then check the service status again:bash
systemctl status
[email protected]
If it’s still active, check the logs for clues:bash
journalctl -u
[email protected]
10. Additional TroubleshootingInstance Units:
[email protected] is an instance of the
[email protected] template. Ensure you’re targeting the correct instance (ttyS0). If other serial ports are involved, repeat the process for them (e.g., ttyS1).
Custom Configuration: Check /etc/systemd/system/ for any custom unit files overriding the default behavior:bash
find /etc/systemd/system -name "
[email protected]*"
If found, remove or edit them.
Firmware/BIOS Settings: Some systems enable serial consoles at the hardware level. Check your BIOS/UEFI settings for serial port configurations and disable if unnecessary.
11. If All Else FailsIf the service still starts, it’s possible that a higher-level configuration (e.g., cloud-init, container setup, or a custom script) is re-enabling it. Check:Cloud-Init: If you’re on a cloud VM, check /etc/cloud/cloud.cfg for serial console settings.
Custom Scripts: Look for scripts in /etc/rc.local or cron jobs that might start the service.
Reinstall Default Config: As a last resort, reset systemd’s configuration:bash
sudo systemctl preset-all
Then reapply the disable/mask commands.
NotesAlways back up configuration files before editing.
If you don’t need any serial console, consider disabling all serial-getty@ services by masking the template:bash
sudo systemctl mask
[email protected]
If you’re unsure about the impact of disabling the service, test in a non-production environment first.
If the issue persists after these steps, please provide:Output of systemctl status
[email protected].
Output of cat /proc/cmdline.
Any relevant logs from journalctl -u
[email protected].
This will help narrow down the root cause.
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本帖最后由 linda 于 2025-8-14 17:25 编辑 ]
