Owner only
Objective
Read the file that only your account is allowed to open.
The briefing
Every file carries a permission string, and a long listing prints it in the first column. Nine characters, in three groups of three:
rwx rwx rwx
you group otherA dash means that permission is not granted. So -rw-r--r-- is readable by everyone, and -rw------- is readable by you alone.
Three files were written into your home directory. One of them is yours alone. Find it and read it.
Set it up
Run this in Termux. It teaches the concept above a second time, then writes the challenge files into your home directory.
ctf start 02 The tool tells you how many files it wrote, never their names.
Then find the flag and hand it in with ctf check 02 LEARMUX{...}.
Hints
Two of them, revealed one at a time. The tool works the same way and remembers how many you have seen, so nothing is spoiled by accident.