2. Command Line interface

3. Function:

4. Interpreter ls * ls f1 f2 f3 common in all shells

5. Shell scripts (programs) differ in syntax from one shell and another

9. Input redirection:

11. Forces a command to read the input from a file instead of from the keyboard.

13. Sends the output from a command into a file instead of sending the output to the screen. As the command generates error messages, these messages are sent to the standard error. Usually error messages are sent to the terminal screen.

16. bash-3.00$ cal | date

17. Tue Nov 10 09:46:23 EET 2009

18. -bash-3.00$ date | cat

19. Tue Nov 10 10:25:45 EET 2009

20. -bash-3.00$ cat | date

21. Tue Nov 10 10:26:34 EET 2009

22. here suspend waiting for input when enter

23. -bash-3.00$ touch f1 | touch f2

24. Both will be touched

25. -bash-3.00$ touch f1 | date

26. Tue Nov 10 10:25:45 EET 2009

28. alias is within the shell

29. To make an alias:

30. alias c=clear

31. alias ls=’ls –l’

32. To display all alias:

33. alias [no option] view all aliases

34. alias alias name view certain alias

35. To delete all alias:

36. unalias -a delete all aliases

37. unalais certain alias delete certain alais

38. To ignore alias:

39. s or /usr/bin/ls to ignore alias

41. At Login

44. Variables that provide information about the user’s environment to every shell program that is started.

45. Local variables

46. Variables that affect only the current shell. Any subshell started would not have knowledge of these variables unless it is exported

48. export VARIABLE

49. You can export the variable while assigning it or after you assigned it

50. Once you export a variable it can be seen by another sub shells not another terminals once you close the terminal it will no more being exists

52. 1572

53. bash-3.00# echo $SHELL

54. /sbin/sh

55. bash-3.00# ps -fp $$

56. UID PID PPID C STIME TTY TIME CMD

57. root 1572 1557 0 11:21:44 pts/3 0:00 bash

58. echo $0

61. ls /usr/bin/*sh

62. ls /usr/bin/w*

64. So if a command take a lot of time in execution would you wait for it or open new terminal or Run this command in back ground while your terminal control this command in back ground

65. Ex:

66. sleep 100

67. The prevent command will prevent you from writing any command for 100 second

68. Run this command in back ground as you know that it will take long time

69. sleep 100 &

70. If you don’t add & from the beginning and then 2 numbers will be displayed the job id [as when more than one job is running in back ground they are put in stack ]and the process id [ we deal with this number in process management]

71. sleep 100

72. ctl + z : Stop the process in the back ground

73. bg jobid : Run the job in the background

74. fg jobid : Run this job back to the foreground

75. jobs : List all the jobs running with their job id

77. ps -f : full information about process

78. ps -e : Prints information about every process on the system

79. ps -u username : List the process of certain user

81. Kill -signal no pid : Send the signal to process

82. 2Interrupt[ctrl+c] exit without saving can be ignored23Stop running [ctrl+z]25Continue running15“default if no signal is specified with kill” exit after saving can be ignored9Terminate without saving and cannot be ignored

83. pkill -signal nopname : Send the signal to process by the name

84. pkill -u username : To terminate the processes owned by this user