8. hidden files.md

Navigate to the root directory and run the ls command with -a to allowing viewing files beginning with . Then read the hidden flag file with cat

$ cd /
$ ls -a
.                      bin        etc    lib64   nix   run   tmp
..                     boot       home   libx32  opt   sbin  usr
.dockerenv             challenge  lib    media   proc  srv   var
.flag-309181069014199  dev        lib32  mnt     root  sys

$ cat .flag-309181069014199

We get the flag pwn.college{wDurLKcELPjkrmIFPEFtS7nrceM.dBTN4QDL3kTO0czW}