Unix File System

1
Unix File System

• Chapter 2.1-2.5

2
Unix file system

• Home directory
• A directory set aside for your personal use
• The starting point when you log in
• Working directory
• Whatever directory you are currently in
• Initially, the working directory is the home
  directory
• The cd command is used to change the working
  directory

3
Typical Unix file system
root (/)
bin
dev
tmp
usr
var
users
classes
csfac
st
fac
staff
spool
mail
ugrad
ms
phd
cs140
001
(all users mail)
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Typical Directories

• bin Software for the shell and most common Unix
  commands
• dev Short for devices, holds the software
  necessary to operate peripherals such as printers
  and terminals
• etc Contains various administrative files such
  as lists of user names and passwords

5
Typical Directories

• usr/users Contains the home directories of users
• tmp A directory used to hold temporary files
• var Files that contain information that varies
  frequently most commonly, mail directories

6
File and Directory Names

• Valid names can be made up of
• Uppercase letters (A to Z)
• Lower case letters (a to z)
• Numbers (0 to 9)
• period (.), underscore (_), commas (,)
• Should not contain spaces or the following
• \ lt gt ( ) ? / !
• You should also avoid naming files or directories
  with Unix commands

7
Absolute Pathnames

• To use a file in Unix, all you need is its name
• To access a file in another directory, you need
  to know its pathname
• A pathname is an address that shows the files
  position in the file system
• Absolute path names give a files location in
  relation to the top of the file system structure

8
Example Directory Structure
root (/)
bin
etc
var
tmp
dev
home
usr
jill
jack
marsupials
Bats
continents
oceans
kangaroo
wombat
bandicoot
opossum
wombat
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Absolute Pathnames

• All absolute path names begin with a /
• Also called full path names
• Use the as a shortcut for the full path to your
  home directory

10
Relative path names

• Usually you are interested in a files location
  relative to where you currently are in the system
  
• A relative pathnames start at the working
  directory rather than the root
• Use .. to refer to the parent of the current
  directory

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Example Directory Structure
root (/)
bin
etc
var
tmp
dev
home
usr
jill
jack
marsupials
Bats
continents
oceans
kangaroo
wombat
bandicoot
opossum
wombat