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The /var/log/dmesg file is not created during boot for Rocky Linux 8

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Operating System and Software

  • Rocky Linux 8

Problem

  • On boot, there is no /var/log/dmesg file after install Rocky Linux 8.
  • I can get dmesg file via command dmesg, is this new design for Rocky Linux 8, or do I need to modify some configuration to generate it automatically?

How to Fix

Re-enabling the /var/log/dmesg log file

1) Create a /etc/systemd/system/dmesg.service configuration file with the following contents

[Unit]
Description=Create /var/log/dmesg on boot
ConditionPathExists=/var/log/dmesg

[Service]
ExecStart=/usr/bin/dmesg
StandardOutput=file:/var/log/dmesg

[Install]
WantedBy=multi-user.target

2) Create the /var/log/dmesg file and verify SELinux contexts

# touch /var/log/dmesg
# restorecon -v /var/log/dmesg

3) Enable the service to start on boot

# systemctl enable dmesg

Origin of the Problem

By design, the /var/log/dmesg file is not generated during boot. The kernel ring buffer is captured within the systemd-journal as well as /var/log/messages, via the imjournal rsyslog plugin.

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