Linux has this fun device file called "/dev/full", which is like its more famous cousin "/dev/null", but when you write to "/dev/full", instead of throwing away the data, it fails. It acts like a file on a filesystem that has just run out of space:
$ echo "Hello World!" > /dev/full
bash: echo: write error: No space left on device
$ echo $?
1
This is a great little tool for testing that programs handle I/O errors correctly. It's inconvenient to create actual filesystems with no space left, or disks that actually fail, but it's really easy to ask a program to write its output to "/dev/full" and see what happens.
System call trace and signals - strace (https://man7.org/linux/man-pages/man1/strace.1.html)
AWS IP ranges - I know this and have used this for a few tasks before