Core functions.
WHAT IT MANAGES
Processor time Memory Storage Devices Users and permissions Networking
WHAT THE KERNEL IS
The core, with direct access to hardware, running with full privilege.
WHAT USER SPACE IS
Where applications run, with restricted privilege.
WHY THAT SEPARATION MATTERS
An application fault should not bring down the system, and applications should not interfere with each other.
WHAT A SYSTEM CALL IS
An application requesting a service from the kernel.
WHAT THE FILE SYSTEM DOES
Organises storage into files and directories, and records where data physically resides.
WHAT PERMISSIONS DO
Determine who may read, write or execute each item.
WHY THAT MATTERS IN SUPPORT
A substantial proportion of access problems are permission problems.
WHAT TO CHECK WHEN ACCESS FAILS
Who the process is running as, and what permissions apply.
WHAT VARIES BETWEEN SYSTEMS
Where things are, and what they are called.
WHAT DOES NOT
These concepts.
