The file system in Linux is very similar to the one you are familiar with in Windows or in Mac. There is a hierarchy of folders and inside folders you can have files. We can also refer to folders as directories.
The root directory is /. This directory is at the top of the hierarchy of directories.
Your home directory is ~. This directory may vary depending on your system, but in EasyCTF, your home directory will be /home/youruser, where youruser is your username.
To change a directory, type cd and the name of the directory you want to go to. Unless you start your path with /, this will always be relative. For example, examine the following system:
/
home
folder1
folder2
file3.txt
file2.txt
file1.txt
(other folders and files)
(other folders and files)
Suppose your current directory is folder1. You may see a prompt like this:
user@easyctf:~/folder1$ _To move down from folder1 to folder2, simply type cd folder2. That's because folder2 is inside of folder1 right now and you can refer to it using a relative path. If you were in your home folder, you would not be able to refer to folder2, because folder2 doesn't exist inside ~. All you can see from ~ is folder1 and file1.txt.
user@easyctf:~/folder1$ cd folder2
user@easyctf:~/folder1/folder2$ _Moving up is simple. In every directory (even empty ones), there are two hidden files: ., which refers to the current folder, and .., which refers to the parent folder. Basically, to move to the parent folder (like from folder1 to ~), just type cd .. and you will be in the parent folder.
user@easyctf:~/folder1$ cd ..
user@easyctf:~$ _