Unix File System

1
Unix File System

• How Unix organizes files and how you can find
  them.

2
Unix file system

• Home directory
• Where your files live.
• You always go there when you log in.
• Working directory
• Whatever directory you are currently in.

3
Typical Unix file system
root (/)
bin
dev
etc
tmp
usr
var
users
classes
csfac
st
fac
staff
spool
mail
ugrad
ms
phd
cs290
jimd
001
(all users mail)
(all people in this class)
4
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.
• 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.

5
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.

6
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.
  
• All absolute path names begin with a /.
• Also called full path names.
• Use the as a shortcut for the full path to a
  home directory.

7
Example Directory Structure
root (/)
bin
etc
var
tmp
dev
home
usr
jill
jack
marsupials
Bats
continents
oceans
kangaroo
wombat
bandicoot
opossum
wombat
8
Absolute Pathnames

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

9
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 the .. to refer to the parent of the current
  directory.

10
Example Directory Structure
root (/)
bin
etc
var
tmp
dev
home
usr
jill
jack
marsupials
Bats
continents
oceans
kangaroo
wombat
bandicoot
opossum
wombat
11
Reading

• Chapter 6.1 6.5
• Manipulating Files and Directories