How to find out why ubuntu is stuck. Where are the logs, and are there any?

Question

linux

Hello.
I put it means ubuntu 15.10, but it often enough (once every 1-2 days for sure) began to hang. Although it was not on the old version of Ubuntu.
Actually the question is, is it possible to find out why it freezes? There are system logs, where do they lie?

Answer 1

If the initialization system is systemd (and in this version, ubuntu like it) - then you can do the following
1. add an option to the kernel parameters for more exhaust
2. When it freezes, after reboot, use journalctl to view the logs from the previous boot before shutdown:
-p 0..3 is a filter by the priority of entries in the logs, from errors to HELL errors, a list of possible options: emerg (0), alert (1), crit (2), err (3), warning (4), notice (5 ), info (6), debug (7).
-b is the range of downloads, for example -b 0will show only logs for the current download, -b 1 for the previous one, -b 0..9 for the last ten.
If you want more detailed logs, you can also add -o verbose , but then you can drown in them :D
systemd does a great job of collecting and aggregating logs in one place, and gives tools for working with them - it's stupid to neglect this. Read more about how to solve problems with systemd - here for example .

Answer 2

/var/log/messages