Shell Programming and Scripting

Hello
I have a question about shell programming
So I recently found out that someone is secretly accessing my files due to my mistake. Of course, now, I changed all the permission so people cannot access my file(s) anymore.
However, I am a little bit mad about the fact and I'd like to find that person
So I was thinking about making simple shell script that does
whoami command and record the output to a file in my folder
So whenever user cd my folder, say "test" folder, then the shell script runs automatically and do "whoami", record the result into a file and save it in my "test" folder
I am wondering if this is possible to do? If so, then could you tell me how?
Also is there other ways I can find the user (who is accessing my file) better way?

By the way, I am using school server so I don't have permission to install or use administrator folders.

Thanks

It is possible to redefine bash/ksh built-ins, eg

Code:

function cd {
    echo $1
    builtin cd "$1"
}

but for this to work like you want this function would have to be sourced by everyone. So you'd either have to put it in everyones ~/.bashrc or ~/.profile, or in one of the global include files.