Week Six Agenda

Week Six Agenda• Announcements• Link of the week• Review week four lab assignment• This week’s expected outcomes• Next lab assignment• Review midterm exam• Break-out problems• Upcoming deadlines• Lab assistance, questions and answers

Link of the week http://www.cert.org/homeusers/HomeComputerSecurity/

This Wed site provides useful information on how to secure your home computer, things you ought to know, and what should be done to secure a home computer.

http://www.istl.org/02-fall/internet.html

Science and Technology Resources on the Internet

Computer Security

This article is written by Jane F. KinKus, who is a Mathematical Sciences Librarian.

http://www.cert.org/homeusers/HomeComputerSecurity/

http://www.istl.org/02-fall/internet.html

Link of the weekWhy do we love Perl?

The Perl Programming Language currently has 21,000 Comprehensive Perl Archive (CPAN) modules.

The CPAN has over 18,000 open source modules available for download.

Perl is a highly capable, feature-rich programming language with over 23 years of development.

Perl is currently being developed.

Perl has over 300 local community groups.

Perl 6 is a sister language, part of the Perl family.

Link of the week

• Definition: Trusted System is one that is replied upon to a specific extent to enforce a specific security policy.

• Definition: Trusted Computing means that a computer will consistently behave in specific ways, and those behaviors will be enforced by hardware and software.

• Where are trusted systems utilized?

Homeland security, law enforcement, and social control

Review week five lab assignmentnames

Bob D'Andrea 222-40-1234 03/19/1947 male

Bo Happy 444-20-2222 01/01/1945 male

Jane Smith 324-78-9990 04/23/1978 female

Razi Jake 564-54-9879 05/26/2005 male

The file named “names” contains the above information.

There are tabs in two places in the above data. One tab is after the name and after the birth date.

Review week five lab assignmentWithout options, print the desired fields in any order.

awk ‘{ print $1, $2, $3, $4, $5 }’ names

The –F option changes the field separator on the command line. The \t is an Escape Sequence for a horizontal tab.

awk –F”\t” ‘{ print $1 }’ names

Review week five lab assignmentPID

An integer used by the UNIX kernel to uniquely identify a process. Just as the US government passes out Social Security Numbers to uniquely identify each individual, Linux assigns each process a unique number as an identifier. This number is called the process ID or PID.

When a process is started, it is given the next available PID, and when it terminates, its PID is released for eventual re-use. To determine the PID of any process belonging to you, enter the ps command at the prompt.

Review week five lab assignmentKeys & Values

%colormap = (“12”, “gray”, “19”, “black”, “30”, “red”);

@codes = keys %colormap; # codes array contains just codes

@colors = values %colormap; # colors array contains the colors

# Printing things out (hash_prt.pl)

while (($key, $value) = each(%colormap)) {

print $key, “, “, $value, “\n";

}

Executing the loop prints:

30, red

19, black

12, grey

Review week five lab assignment Signals

Signals are a form of process communication. Because they can come from another process, the kernel or the process itself, they might be better thought of as events that occur as a program runs. A crude example might be the bell most of us remember from our early days in school; when the bell rang, we reacted by switching from playful children to industrious students.


The kill –l command will display the signals available on your system.

HUP USR1 BUS

INT SEGV FPE

QUIT USR2 KILL

ILL PIPE

TRAP ALRM

IOT TERM


For each signal there is a default action, almost all of which terminate the process. For most signals, a program may specify another action—this is called catching or handling the signal—or may specify that no action occurs, which is called ignoring the signal. The signal SIGKILL cannot be caught or ignored; it always terminates processes.

Review week five lab assignmentkill command

Used to send a signal to another process.

The kill command is used on Linux and other UNIX-like operating systems to terminate processes without having to log out or reboot (i.e., restart) the computer.

Format: kill [signal or option] PID(s)

kill -l

kill –l TERM

kill –l KILL

Review week five lab assignmentkill command

To determine the PID of any process belonging to you, enter the ps command at the prompt.

The ps command will print, for each of your processes, a line containing the process's PID, the amount of time the process has used and the command with which the process was started

test_build.sh

This script is used to execute the make command which in turn will call the makefile.

test_build.sh -> make -> makefile

Review week five lab assignment

SourceFile

SourceFile

SourceFile

SourceFile

SourceFile

Object File

Object File

ObjectFile

Object File

ObjectFile

LinkerRuntimeLibrary

ExecutableProgram

Source/Object/Executable Drawing


Define make command: The make utility is a software engineering tool for

managing and maintaining computer programs. Make provides most help when the program consists of many component files. As the number of files increase in a project, so to does the compile time, complexity of compilation. The likelihood of an error occurring with human(s) manageability is high.


Define the makefile: Make goes through the makefile (descriptor) file

first starting with the target it is going to create. Make looks at each of the target’s dependencies to see if they are listed as targets. It follows the chain of dependencies until it reaches the end of the chain and then begins backing out and executing the commands found in each target's rule. Actually every file in the chain may not need to be compiled. Make looks at the time stamp for each file in the chain and compiles from the point that is required to bring every file in the chain up to date. If any file is missing it is updated if possible.

•


Makefile Components• Comments within a makefile (#)• makefile continuation lines (\)• Rule tells make both when and how to make a

file• Dependency Line is a line with a colon (:) test_build.sh contains the make command

which calls the makefile. The test_build.sh script is located in the /tmp directory.

• Demonstrate makefile script under ~dandrear/temp (cs.franklin.edu)


Key Points about the makefile

1. Makefile recompiles all source files for an entire project.

2. Makefile recompiles only those files that have different time stamps.

3. Bottom up control flow.

4. Rules are shell commands.

Review week five lab assignmentKey Points about the makefile The file names used in this example have been abbreviated

for simplicity.

C++ compilations end in .cpp suffix.

The .c suffix extension causes the C compiler to be invoked.

The .o suffix represents a object file.

The .h suffix represents a header file.

The g++ is a compiler, and not a preprocessor.

The G++ builds object code from your C++ program source.

The –c option, compiles source to object code.

The –o option, compiles object code.

Review week five lab assignmentOther software products that perform similar bundling operations

- ANT developed by Apache Jakarta- ANT2 supplied from the Free Software

Foundation which is part of Red Hat.

What is a dependency between source files?main.cpp employee.cpp address.cpp

What are the two parts of a dependency rule? 1) What files a file is dependent on

2) Rule that tells how to recompile the fileWhat are the differences between a makefile and a shell script?The rules in a makefile are executed based on dependency, and

not sequential order. Scripts execute in sequential order.

Review week five lab assignmentTarget : Dependencies (prerequisites)<tab> Rule prog: a.o b.o c.o g++ -o a.o b.o c.oa.o: prog.h a.c g++ –c prog.h a.cb.o: prog.h b.c g++ –c prog.h b.cc.o: c.c

g++ –c c.cc.c: c.y

g++ -c c.ymv y_table.c c.y


Review week five lab assignmentmyProgram

main.o employee.o address.o

employee.cppemployee.h main.cpp address.haddress.cpp


Key Points About Perl

1. Dynamic typing

2. Dynamic allocation of memory for arrays and hash tables

3. Both procedural and object oriented programming capabilities

4. Rich third party software and use of modules


• Regular expression (a.k.a. regex or regexp)

Is a pattern that describes a certain amount of text. A basic regular expression could be the single character, e.g.: a

Jane is a women.

It will match the first occurrence in the string. If succeeding matches are desired, the regex engine must be instructed to do so.

Review week five lab assignmentRegular Expression Special Characters * Open square bracket [ * Backslash \

* Caret ^* Dollar sign $* Dot .Pipe symbol |Question mark ?Asterisk ** Plus sign +Opening and closing round brackets ( )

Review week five lab assignmentAwk Script

# Author: Bob D'Andrea

# Script name: awksrc

# Command line awk -f awksrc test.txt

# Command line: awk -f awksrc

/^$/ { print "This is a blank line." }

/[0-9]+/ { print "That is an integer." }

/[A-Za-z]+/ { print "This is a string." }

Review week five lab assignment• Perl Hash table is an unordered set of scalars,

accessed by some string value that is associated with each scalar.Keys are 12, 19, and 30.Values are gray, black, and red.%colormap=(

“12” => “gray”,“19” => “black”,“30” => “red”,);

%colormap = (“12”, “gray”, “19”, “black”, “30”, “red”);

%members = (John => "father", Paul => "son", Marie => "daughter");


Define Comma – arrow:

The comma-arrow (=>) operator is used to initialize the %members hash variable in the previous slide lines of code. The left side of the comma-arrow operator is expected to be a simple string and therefore it is not necessary to be quoted.


BLACK RED GRAY

YELLOW BLUE WHITE

GREEN AMBER GOLD PINK

11 12 13

21 22 23

31 343332

Hash Table

Week six expected outcomesUpon successful completion of this module, the

student will be able to:• Create makefile scripts for software programs. • Use pattern rules in make files. • Create an effective PowerPoint presentation. • Create make files with multiple targets. • Install software packages on a server.

Next lab assignmentInstalling software under UNIX is not always straightforward and easy. System administrators must be familiar with the layout of the file system. During a software installation, the possibility exists that the system could panic and/or have a hard disk failure.

Next lab assignment

Installation Software Package MethodsPackage manager

- What are the tasks of a package manager? - The version of UNIX dictates which package

manager will be used.- Many Linux versions utilize the Debian

Package Manager. Manual

- The utilization of makefiles or shell scripts to automate the install as much as

possible. - On occasion, the installation of software is done by sending the source code to the site.

- What steps are required to install a new software version?

- How is a “configure” script utilized?

Next lab assignment

Installation Software Package MethodsPackage manager

- Linux uses yum and rpm as there package manager.

- Software has to be set or identified to use rpm. Otherwise, the software is configured

manually.

Next Lab Assignment

shell

Kernel

Hardware

Assembler

Firmware

Next Lab Assignment

Midterm Exam Outline has been email to all students.

Midterm Exam will be October 15 through 20. If there are any problems taking the exam, call me at 614.519.5853.

Thank you,

Break-out problems• touch command• dot command• dot dot command• What function does the makefile provide a project? • What are the two parts of a dependency rule?• What language is used for writing makefile rules?• What two methods are used for installing software

packages?• What is a regular expression• American National Standard Institute (ANSI)

Upcoming deadlinesLab Assignment 6-2 is due October 21, 2012

Lab Assignment 6-1 is due October 28, 2012

Lab Assignment 7-1 (midterm) has to be completed by October 21, 2012.

Questions and answers

• Questions• Comments• Concerns

• Are there questions regarding the mid-term outline?

• After class I will help students with their scripts.

Documents

Week Six Agenda