File Permission


### mode of access - read, write, execute
FCB - Storage structure consisting of information about a file.
- three classes of users - each has different mode access
1. owner access - read, write, execute - 7
2. groups(unique name) access - read, write - 6
3. public access - execute - 1
so if you want to 보안 OS, architecture is most important 암호화는 보안의 일부 system information 보안 important





