Kernel. Misc

# Options
sudo sysctl -a
less /usr/include/linux/sysctl.h

ulimit -a # Sets or reports user resource limits.

cat /proc/sys/kernel/ostype
cat /proc/sys/kernel/osrelease

ls /lib/modules/$(uname -r)/kernel/fs
List open files
lsof -p

File
stat text.txt
file arch.tar.xz
fuser -v server.sock

Inode
ls -i
df -i

Port
fuser -v -n tcp 11100

Interrupts

Timing

Page and buffer cache fadvise, madvise, readahead

pdflush