$ sudo apt install ncdu
    > Not enough free space

Fuck!

Actually, one trick I learned was to create a dummy file full of zeroes or rand, maybe 200MB or so, and place it in an obvious location (e.g /) for easy deleting in such a crisis.

Another trick is to have a 1GB file called DeleteMeWhenDiskIsFull.

Then you can delete that file and ponder your life choices that led to that situation.

Just remember to create it again :)

That's the reason why typical Linux (or Unix) filesystem comes with a setting to set reserve some space for root account.

Doesn't help if the disk is filled by processes running as root, of course.

Or a "journalctl --vacuum-time=1d" will usually clear a lot of space

One of the first things I did in my new position was to add ncdu (and mysqltuner) to our Ansible playbooks. It's that useful for me - I probably use it every other day at least.

I've saved the day once or twice by having a built of ncdu that I can just copy to /dev/shm to figure out what went haywire.