Installation date

Source

# Method a
$ sudo tune2fs -l /dev/sda1 | grep 'Filesystem created:'

# Method b
$ sudo rpm -qi basesystem | grep Install

Forced reboot

Source

If the usual shutdown/reboot fails:

# Enable SysRq
echo 1 > /proc/sys/kernel/sysrq

# Immediate reboot
echo b > /proc/sysrq-trigger

journalctl

Source

By Unit

journalctl -u <unit>.service [--since today]

By component

journalctl /usr/bin/bash

By priority

$ journalctl -p <prioritynumber|priority> -b
  • 0: emerg
  • 1: alert
  • 2: crit
  • 3: err
  • 4: warning
  • 5: notice
  • 6: info
  • 7: debug