Week Three Agenda

2. Week Three Agenda Administrative Issues Link of the Week Review Week Two Information This Week’s Expected Outcomes Next Lab Assignment Break-Out Problems Upcoming Deadlines Lab Assistance, Questions, and Answers

3. Administrative Issues This is the last week for identifying a proctor. Most students have already selected their proctor to administer their midterm exam. This same proctor list will be used for the final exam unless a change request is submitted to the Student Learning Center two weeks prior to the final exam date.

4. Link of the Week APA Style writing guidelines will be utilized for all lab assignment reports . APA Style Sixth Edition http://www.apastyle.org/learn/ APA Style Writing Workshop http://www.franklin.edu/student-services/student-learning-center/academic-support/workshops.html Grading will focus mainly on capitalization, punctuation, grammar, and citation.

5. Link of the Week Linux Forums Web Site This web site allows individuals to post questions about Fedora Linux and Redhat Linux. The people that maintain this site are knowledgeable users of these operating systems. If your experiencing problems with commands or just want to learn more about these systems, you can find this type of information at this site. http://www.linuxforums.org/forum/redhat-fedora-linux-help/73994-system-commands-not-working-unless-sbin.html

6. Review Week Two Information Caveat: Knoppix software was designed to be used as a Live CD because of specific features that make it’s performance and stability very suitable. It has been noted in several articles that Knoppix works best from a Live CD. Knoppix enthusiasts have attempted to install this software on a hard disk and encountered problems in the process. These problems are most pronounced when installing updates and new software.

7. Review Week Two Information What is the next user interface going to be? The textual (command line) and the visual (graphical user) interfaces are the two most common modalities used to support engineers in network and system administration positions. The command line interface is recognized as the first generation and the graphical user interface is considered the second generation. Currently, research is trying to determine the next best interface. The command line interface is known as, “under the hood” method of interacting with the operating system.

8. Review Week Two Information CLI Benefits: Manipulate textual data Quick customization of data allows engineers the ability to change data to another form Excellent for filtering data on systems Commands are rich, expressive, flexible, and powerful GUI Benefits: Reduces data overload Simple filtering and manipulation of the data Excellent for displaying trends in data

9. Review Week Two Information Users can connect the standard output of one command to standard input of another command by using the pipeline operator (|). Demonstrate ps -ef ps –ef | wc –l ps –ef | awk ‘{print $2}’ ps –ef | grep dandrear ls –l | cut –c1-3 who | sort > test_file.txt The output of the who command is piped to the sort function and written in ascending order in the test_file.txt file. The “who” and “sort” commands execute in parallel.

10. Review Week Two Information Commands who –b (time of last system boot) who –d (print dead processes) who –r (print current run level) List directory entries using the ls –l | less command drwxrwxrwx permissions (directory) -rwxrwxrwx permissions (file) lrwxrwxrwx permissions (Symbolic link) -rwxrwxrwx 2 dandrear (Hardlink) brw-rw---- permissions (block) crw------- Permissions (character)

11. Week Two Information A process associates a number with each file that it has opened. This number is called a file descriptor. When you log in, your first process has the following three open files connected to your terminal. Standard Input (stdin) : Filedescriptor 0 is open for reading. /dev/stdin Standard Output (stdout): File descriptor 1 is open for writing. /dev/stdout Standard Error (stderr): File descriptor 2 is open reading. /dev/stderr Demonstrate ls –a > /tmp/output 2>&1 > is equivalent to 1> < is equivalent to <0

12. Week Two Information

13. Review Week Two Information A file descriptor is generally an index for an entry in a kernel-resident data structure that contains information on all open files. Each process on the system has its own file descriptor table. A user application passes the abstract key to the kernel through a system call, and the kernel accesses the file for the application. What is a data structure? A data structure is a specific way of storing and organizing data in a computer so that it can be accessed with high efficiently. Data structures can be used as a single place for storing unrelated information.

14. Review Week Two Information A data structure is a particular way of storing and organizing data in a computer so that it can be used efficiently. Different kinds of data structures are suited to different kinds of applications, and some are highly specialized to specific tasks. Some common data structures: array, hash table, linked list, queue, and stack

15. Review Week Two Information The grep command searches the named input file(s)for lines containing a given pattern. Each line found is reported to standard output. Demonstrate: grep UNIX foobar_3 grep ‘^UNIX’ foobar_3 grep ‘UNIX$’ foobar_3 grep pattern foobar_1 grep pattern * The find command lists all pathnames that are in each of the given directories. Demonstrate: find / -type d –print find ~dandrear –type d -print find . –print find / -name foobar

16. Review Week Two Information Redirection Symbols: Redirect the standard output of a command to a file. date > /tmp/date_saved Redirect the standard input of a command so that it reads from a file instead of from your terminal. cat < ~dandrear/Summer_2012_Solutions/test.txt Append the standard output of a command to a file. cat foobar_2 >> foobar_1

17. Review Week Two Information Korn Shell Syntax and Commands srchfile.sh $1 $2 original=$PWD cd $original cd $2 listing=`ls –l | cut –c52-80` for file_name in $listing do (boundary) Action Statements (block of statements) done (boundary)

18. Review Week Two Information Commands ls –l | more ls –l | less (count the fields/use “q” to quit) ls -a (does not hide entries) less man (utilizes the less command for reading online documentation).

19. Review Week Two Information Shell Syntax > test_file cat /etc/passwd grep x /etc/passwd | cut –d’:’ –f1 chmod 705 * chmod 705 test_file grep line ~dandrear/Summer_2012_Solutions/foobar_1 find ~dandrear –type d -print myshellArray[1]=$1 $0

20. Review Week Two Information Commands The tilde (~) symbol is used to represent the user’s current home directory (e.g. /home/dandrear) Command line arguments example: ./add_all 5 10 8 Command line argument syntax. $0 = ./add_all, $1 = 5, $2 = 10, and $3 = 8

21. Review Week Two Information Demonstrate /home/dandrear/.profile umask 077 The umask variable contains the default permissions for a file and a directory. Variables Used by Korn Shell: HOME = is set to the full path name of your login directory (/home/dandrear) echo $HOME PATH = contains the command search path. It is set to a series of path names separated by colons (:). echo $PATH

22. Review Week Two Information Variables Used by Korn Shell SHELL = This entry may be set by the system administrator to the path name of a shell interpreter other than the standard bash. echo $SHELL TERM = specifies what terminal you are using. TMOUT = variable contains the integer attribute. If you set the value greater than zero, ksh terminates if you do not enter a command within the prescribed number of seconds after ksh issues the PS1 prompt. MAIL = Name of your Mail files EDITOR = Pathname for your editor

23. Review Week Two Information Manual (man) Page Man formats and displays the on-line manual pages. If you specify section, man only looks at that section of the manual. Name is normally the name of the manual page, which is typically the name of a command, function, or file. However, if name contains a slash (/) then man interprets it as a file specification. Each section has an introduction which can be obtained with, e.g., "man 2 intro“ or “man ./foobar_1”. If MANPATH is set, man uses it as the path to search for manual page files.

24. Review Week Two Information echo $MANPATH /usr/local/man:/usr/local/info:/usr/share/man:/opt/SUNWspro/man Man Page Sections 1 Commands 2 System calls 3 C library routines 4 Devices and networks 5 File formats 6 Games and demos 7 Miscellaneous 8 System administration.

25. Review Week Two Information Types of File and Directory Access: AccessFile MeaningDirectory Meaning r View file contents Search directory contents w Alter file contents Alter directory contents x Run executable file Make your current directory -rwx------ Owner (columns 2-4) 700 (111000000) ----rwx--- Group (columns 5-7) 070 (000111000) -------rwx Other (columns 8-10) 007 (000000111)

26. Review Week Two Information Shell and Programs Access: To run a shell script, you will need read (r) and execute (x) access (r-x). The read access mode is a binary 4. The execute access mode is a binary 1. To run a binary executable program, you will need execute (x) access (--x). The execute access mode is a binary 1.

27. Week’s 2 & 3 Expected Outcomes Upon successful completion of this module, the student will be able to: • Create scripts using shell/Perl variables and program control flow. • Use redirection and pipes to combine scripts and executables. • Use man page system and find script tools. • Discuss Perl Language

28. Next Lab Assignment Introduction to Perl: Perl - Practical Extraction and Report Language Originally developed by Larry Wall, a linguist. Perl is 21 years old and Perl 5 is 14 years old. • Perl is a simple language - Compiles and executes like a shell script or a batch file - Perl doesn’t impose special growth limitations on arrays and data strings - Perl is a composite of C, AWK, and Basic - Originally developed to process text and automating tasks.

29. Next Lab Assignment Perl’s range of flexibility - System administration - Web development - Network programming - GUI development Major features - Procedural Programming Sequence or unstructured statements Includes routines, subroutines, methods, or functions - Object Oriented Programming Module uses “objects” and their interactions to design applications and computer programs.

30. Next Lab Assignment Major features (continued) - Powerful built-in support for text processing - Large collection of third-party modules.

31. Next Lab Assignment • Why is awk language so important? It is an excellent filter and report writer. Many UNIX utilities generate rows and columns of information. Awk is an excellent tool for processing these rows and columns, and is easier to use awk than most conventional programming languages. Perl recognized the importance of awk, so it was included and enhanced in Perl.

32. Next Lab Assignment The Advanced Scripting lab assignment requires two shell scripts to be written. srch.sh srchfile.sh Demonstrate Execution of srch.sh and srchfile.sh Case #1: ./srch.sh <pattern> <file name / directory name> Case #2: ./srch.sh <pattern> <.> The srch.sh script will call the srchfile.sh script to perform a specific task. The srchfile.sh searches for a file with a pattern and outputs the matching information to standard output. After all directory entries have been read, control is returned to the main script, srch.sh.

33. Break Out Problems 1. scalar@ARGV 2. $ARGV[0] 3. filter 4. unless 5. $NUMBER 6. exit 1 7. $ARGV[1] 8. % (%directory) 9. $ ($quote) 10. @ (@names) 11. Regular expressions 12. tr [a-z] [A-Z] < foobar > /tmp/foo

34. Next Lab Assignment Read your Programming Perl text book. Chapter One (1) Chapter Two (2) Review Chapter 32: Standard Modules Review Chapter 33: Diagnostic Output Messages Read Module Two listed under the course web page.

35. Upcoming Deadlines • Lab Assignment 1-1, Obtain a Proctor for Exams, due May 6, 2012. • Lab Assignment 2-1, Simple Shell Scripting, due May 13, 2012. • Lab Assignment 3-1, Advanced Scripting, due May 20, 2012. • Lab Assignment 4-1, Simple Perl Exercise, due May 27, 2012.

36. Lab Assistance, Questions and Answers Questions Comments Concerns After class I will help students with their scripts.