1. To navigate to the root directory  $ cd /

2. To navigate to the home directory  $ cd or $ cd ~

3. To see the file or folder listing  $ ls 

4. To delete files $ rm file_name  
   To delete directory $ rm ­R
5. To make directory $ mkdir new_dir

6. To display file system disk space $ df -­h

7. To display amount of free and used space in RAM $ free ­m

8. System network interface $ ifconfig

9. To add group $ addgroup newgroup 

10. Add user $ adduser new_user

11. To assign password $ passwd

12. Add user assad to new group $ adduser assad newgroup

13. To get Information $ info 

14. To escape editor Press 'q' / Press Esc, :+wq = write quie write quie / :q = quit Exit, if no change

15. Change directory or file mode $ chmod xxx file_name
    X=4: for read only.
    X=2: for write only.
    X=1: for execute only.
16. To change group attribute of a file or directory $ chgrp group_name file_name 

17. Install software in ubuntusudo $ apt­get install software_name
   
18. Clear the terminal $ clear

19. To display the name of your current directory $ pwd

20. To view process currently running $ ps aux

21. Commant to start the service $ start 

22. stop Commant to stop the service

23. To lock user account $ sudo passwd ­l user_name
    To unlock user account $ sudo passwd ­u user_name

24. To enable root directory $ sodo passwd root

25. To create a file named filename1 $ touch filename1

26. Display date $ date 
    Display date in s $ date +"%H:%M:%S"
    Display calender $ cal

27. Display current user $ whoami 

28. Display system information $ uname

29. Logged on information $ who 

30. For how long the system has been running $ uptime 

41. To display text $ echo 'text display'
42. To see the path $ whereis bash
                    $locate
43. To display standard path $ which wesnoth

44. Used to concentrate more than one files $ cat /etc/mtab

45. Text editor mode $less /etc/mtab 

46. Super user $ sudo su ­

47. Find out processes $ ps ­elf | less

48. Show system configuration $ lshw

49. Find out open ports $ netstat

40. Stop mysql $ /etc/init.d/mysql stop or service mysql stop

51. Start mysql $ /etc/init.d/mysql start or service mysql start

52. To update ubuntu $ apt­get update
    To upgrade $ apt­get upgrade

53. To rename file $ cp filename1 filename2

54. To rename folders $ mv filename1 filename2

55. Networking stop / internet stop $ sudo /etc/init.d/networking stop 

56.  Networking stop / internet start $ sudo /etc/init.d/networking start

57. To copy file or folders $ cp source destination

58. Folder copy $ cp -r /data/cmail /data/assad  [cmail folder will be copied to assad folder ]

59. Folder/file move $ mv source destination

60. Secure copy [from remote pc] $ scp source destination 
    if the test folder does not exists then the file is saved as 'test' in root(/)
    scp cention@192.168.0.105:/home/cention/Documents/myth.odt /home/subarna/Desktop/assad/
    scp cention@192.168.0.105:/home/cention/Documents/myth.doc_0.odt .
    (if the destination is the default location so, . (dot) is enough as destination)

61. Remove file $ rm filename 

62 To make a shortcut $ ln -­s source destination
   e.g.$ ln -­s /home/cention/Documents/kommuninfo/portal /var/www/