Introduction to Unix

1
Introduction to Unix

• Winter Term, 2002

2
Basic Definitions

• The Kernel - the memory resident part of the Unix
  operating system that interacts with the hardware
  to perform its tasks
• The Shell - the Unix command line interpreter
  the language used to communicate with the Unix
  kernel
• A Shell script - a file consisting of a series of
  shell commands
• The source command - the command issued at the
  command line that reads a shell script as if
  its contents had been typed at the terminal

3
Basic Definitions
The GUI or CLI
Hardware
The Shell
The Kernel
Hardware
4
Special Characters

• / the forward slash delimits directory names /
  is the root directory
• . a single dot (or sometimes ./) is the Unix
  shorthand for the current directory
• .. the double dot (or sometimes ../) is
  shorthand for the parent directory

5
Paradigm

• Unix (Irix, Linux, etc.) lets the user do almost
  anything!
• You must know what you want to do before
  attempting to do it!
• Most commands are non-intuitive (to the new user)
• More than one shell is available - well use tcsh
• The shell is case sensitive!

6
Login/Logout Process

• Loggin in
• The users shell is selected
• System wide scripts are sourced and thus
  system setup is performed
• The users command files are sourced
• ./.login and ./cshrc
• For further details type man sh or man csh
• Logging out
• simply type logout or d (ctl d)

7
Help

• From the command line issue the command
• man lttopicgt
• From the GUI there is graphical on-line help
  available

8
Useful Commands

• z suspend execution of a current interactive
  job
• bg resume execution of suspended job in the
  background
• fg resume execution of suspended job in the
  foreground
• jobs list all background jobs and their status
• ls -la list the contents of the current
  directory
• ps list all current running processes
• apropos ltkeywordgt find the appropriate man page
  for a given keyword
• telnet lthostnamegt login to a remote host
  computer
• ftp lthostnamegt transfer files from a remote
  computer

9
Useful Commands

• df display the filesystem lists the current
  mounted filesystems (directories)
• grep string ltfilegt search for a string of
  characters in a particular file
• more ltfilegt scroll through the specified file
  and list its contents one screen at a time
• cp ltfilegt ltlocationgt copy a file to another
  location (directory)
• cd ltdirectory pathgt change directories to a new
  one
• mkdir ltdirectory namegt make (create) a new
  directory under the current one
• pwd show (print) working directory
• xhost lthostnamegt allow the computer named
  hostname to have X-windows access to the
  current one