Lecture Notes for Operating Systems

Files and Directories, 20 November 2000

1. the file system - provides storage that's large, permanent, and easily sharable

2. files

   1. named collections of data - name + extension; version information; where's the semantics

   2. file structures

      1. unstructured - a byte sequence

      2. record oriented - but what is a record; fixed and variable length

      3. keyed structures - tree-like; more towards databases; databases as file systems

   3. file types

      1. text or binary - human readable

      2. character special or block - device access

      3. magic numbers - file and /etc/magic

      4. what determines the semantics - ease vs. flexibility

   4. file access patterns - sequential, random; optimize access patterns; usually assume random

   5. file attributes - information about files; protection, password, creator, owner, rwx permissions, length, modified times, temporary

   6. file operations - create, delete; open, close; read, write, append; seek, get or set attributes, renaming

3. directories - files about files

   1. over-all file organization - flat, semi structured, hierarchical

   2. directories contain information about structure and files

      1. path naming - absolute, relative

      2. operations - link and unlink

This page last modified on 20 November 2000.