Where can I find the log files for mounting disks?

Question

I understand if I boot from a live cd I can see all the system logs under System > Administration > File Log Viewer

I have a major error with a disk not mounting and I want to trace i tback to the last time it did work and what may have corrupted the ext4 filesystem on it.

So within the File Log Viewer Where do I start examining?

Solution 1

I'd guess /var/log/dmesg

You can find all logs that mention mounting or ext4 like this:

grep -e mount -e ext4 -lR /var/log 2> /dev/null

dmesg seemed to be the most relevant to me. And there are archived versions (dmesg.*).

Solution 2

You can find aditional information in syslog

grep 'Mounted' /var/log/syslog*

or find mounted and unmounted logs

grep 'Mounted\|Unmounted' /var/log/syslog*

Comments

[user941105]

Are you only looking at the logs that were generated by the LiveCD starting up? Or are you looking at the logs on the host filesystem?

[Rinzwind]

ah you can also just search all the logs from commandline: cd /var/log/ and do a grep -R mount * (assuming you want to see all lines that contain mount).

[Sindarus]

I know this has been downvoted because it does not allow to see when a disk has last been successfully mounted (as was asked), but you can still find some interesting debugging info there as why a disk was not mounted or why it was automatically unmounted.

[linuxUser123]

I am a beginner and somehow this command was easier to use.

[R B]

I voted for this response because I didn't find /var/log/dmesg in Ubuntu Studio 18.04. I did find a mount error code in /var/log/syslog; unfortunately, it didn't reveal anything I didn't already know.