Filesystem Hierarchy Standard - Wikipedia https://en.m.wikipedia.org/wiki/Filesystem_Hierarchy_Standard
If you want to flush the file system cache(s) then have a look at this blog post:
https://www.tecmint.com/clear-ram-memory-cache-buffer-and-swap-space-on-linux/
This command needs to be run as root and is “safe”as it only clears the PageCache (not dentries and inodes):
sync; echo 1 > /proc/sys/vm/drop_caches
Anyone who sees it for the first time might wonder why set -ex appears in scripts.
set -ex - The most useful bash trick of the year
Three Critical Resources You Should Use to Harden Your Linux Server - Make Tech Easier https://www.google.com/amp/s/www.maketecheasier.com/resources-harden-linux-server/%3famp
CIS Benchmarks Landing Page https://learn.cisecurity.org/benchmarks
Lynis - Security auditing tool for Linux, macOS, and Unix-based systems - CISOfy https://cisofy.com/lynis/#operating-systems