Where things live.
WHAT THE LAYOUT IS
A standard Unix hierarchy, with Apple-specific additions.
WHAT THE KEY LOCATIONS ARE
The user's home directory The system library, for system components A library at the root, for items shared between users A library within each home directory, for that user's items Applications, at the root and optionally per user
WHY THERE ARE SEVERAL LIBRARY DIRECTORIES
Scope. System, all users, or one user.
WHAT IS HIDDEN BY DEFAULT
The library within a home directory, and files beginning with a dot.
HOW TO REACH IT
Through the menu option that reveals it, or by path.
WHAT THE SYSTEM VOLUME IS
A signed, read-only volume containing the operating system.
WHY THAT EXISTS
So the system cannot be modified, which prevents a class of attack and makes updates reliable.
WHAT THAT MEANS PRACTICALLY
You cannot write to system locations, even as an administrator.
WHERE TO PUT YOUR OWN THINGS
Under the library at the root, or in a user's own library.
WHAT TO KNOW ABOUT CASE SENSITIVITY
The default volume format is case-insensitive but case-preserving.
WHY THAT MATTERS
Code working locally can fail on case-sensitive systems.
