1. File and File System Structure
Chapter 7
File and File System Structure

2. Objectives To explain the UNIX file concept
To discuss various types of files supported by UNIC
To describe attributes of a file
To explain the notion of pathnames
To explain the user view of the UNIX file system
To describe the user’s interface to the UNIX file system - browsing the file system
To discuss representation of a file inside the UNIX system
To describe how a UNIX file is stored on the disk
To explain the concept of standard files in UNIX
To cover the commands and primitives ~ , . , .. , / , PATH, cd, echo, file, ls, mkdir , pwd , rmdir
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

3. Types of Files Simple/ ordinary file Directory Symbolic (soft) link
Special (device) files – block special files and character special files
Named pipe (FIFO)
Socket
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

4. Types of Files (Contd) Simple/ Ordinary File
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

5. Types of Files (Contd) Directory
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

6. Types of Files (Contd) Link File Special (Device) File
A Link File is created by the system when a symbolic link in created to an existing file.
Special (Device) File
A special File is a means of accessing hardware devices, including the keyboard, hard disk, CD-ROM drive, tape drive and printer.
Character Special Files
Correspond to character-oriented devices (e.g., Keyboard)
Block Special Files
Correspond to block-oriented devices (e.g., a disk)
Named Pipe (FIFO)
Tools that enable processes to communicate with each other
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

7. File System Structure File System Organization
Home and Present Working Directories
$HOME, ~, $home
pwd, ., ..
Pathnames: Absolute and Relative
Some Standard Directories and Files
Root directory (/), /bin, /dev, /etc,/lib…
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

8. A Typical UNIX File System Structure
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

9. Navigating the File Structure
Determining the Absolute Pathname for Your Home Directory
echo [string]
Browsing the File System
cd [directory]
ls [options] [pathname-list]
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

10. Navigating the File Structure (Contd)
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

11. Navigating the File Structure (Contd)
Creating Files
pico, vi, emacs
Creating and Removing Directories
mkdir [options] dirnames, rmdir [options] dirnames
Determining File Attributes
ls –l, ls –i , ls –al , ls –F
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

12. Navigating the File Structure (Contd)
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

13. Navigating the File Structure (Contd)
$ ls -i
12329 courses memos personal
$ ls -al ~/courses/ee446/exams
drwxr-x-- 1 sarwar faculty 512 Mar 16 08:24 .
drwxr-x-- 1 sarwar faculty 512 Jan 29 13:27 ..
-rwxr--r-- 1 sarwar faculty 1863 Mar 16 11:10 mid1
-rwxr--r-- 1 sarwar faculty 459 Apr 11 14:34 mid22
drwxrwxrwx 1 sarwar faculty 512 May 12 23:44 solutions
$ ls -F /
bin/ dev/ etc/ lost+found/ tmp/ usr/ unix*
$ ls -l ~/courses/ee446/lab[^5]*.c
...
$ ls ~/[^0-9]*.[c,C] $
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

14. Determining the Type of a File’s contents
file [options] file-list
$ file /*
all.backup: POSIX tar archive
bin: directory
dev: directory
etc: directory
install: symbolic link to var/lib/LST
lost+found: directory
tmp: directory
usr: directory
unix: ELF 32-bit LSB executable $
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

15. File Representation and Storage in UNIX
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

16. File Representation and Storage in UNIX
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

17. Standard Files and File Descriptors
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.

18. Standard Files and File Descriptors (Contd)
Copyright © 2005 Pearson Addison-Wesley. All rights reserved.