A Thinkpad X220 (Core-i5, SandyBridge, Intel GMA) running Precise 64bit has rebooted hard twice in the last four days. I was doing nothing more than writing an email. No warning. It just went black, and the next thing I saw was the Lenovo boot screen.

Where should I look to find the cause? I fear that this immediate reboot does not leave time for logs to be written...



Check /proc/sys/kernel/panic, if it's value is 1 then server will immediately reboot on panic. Bad drivers can cause kernel panic.

If it's not panic check last issue of reboot, maybe overheating is the issue.

last reboot
  • This command shows that my system came up with a new kernel. Ubuntu 12.04 64 bit. 3.2.0-63 after reboot, 3.2.0-61 before – Antonios Hadjigeorgalis May 26 '14 at 14:20
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    This led me to checking etc/apt/apt.conf.d/50unattended-upgrades I had set Unattended-Upgrade::Automatic-Reboot "true"; I changed it back to the default setting of false. – Antonios Hadjigeorgalis May 26 '14 at 15:31
  • @Antonios does this auto reboot is without warning? – Aquarius Power Dec 5 '14 at 20:38
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    last |head -n 50 wow, I just found this: 13:55 - crash (04:35) what gonna track how that happened, thx! – Aquarius Power Dec 5 '14 at 20:44
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    @AquariusPower Yes, it was. my issue went away after changing the unattended-upgrades setting. – Antonios Hadjigeorgalis Dec 5 '14 at 21:49


  1. dmesg - May not show items from before last boot, but very useful if the system is still up


  1. /var/log/syslog - System wide logger, use tail /var/log/syslog or less /var/log/syslog
  2. /var/log/kern.log - Kernel log, same as above
  3. /var/log/*
  • Thanks so much for your answer. The problem is - as stated in my question - that the system is not up anymore. I believe that I had some kind of hardware issue. – Andre Nov 7 '12 at 3:49
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    I went on a quick google hunt to check if the above files persist across reboots (since I'm not infront of a linux computer atm) and I found this site, which I found extremely informative: softpanorama.info/Commercial_linuxes/troubleshooting.shtml – Huckle Nov 7 '12 at 17:23
  • Can you elaborate on how the output of dmesg is supposed to help? My machine has just randomly rebooted, and if I understand your suggestion right, then dmesg cannot help here, right? – tchakravarty Aug 27 '16 at 11:05
  • I would like to add this grep "Jan 11 01" /var/log/* -rah 2>/dev/null |sort so you can target the day and the hour (ubuntu 16.04 but some info are version independent) – Aquarius Power Jan 11 at 16:40

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