Week Five Agenda Link of the week Review week four lab assignment This week’s expected outcomes Next lab assignment Break-out problems Upcoming deadlines Questions and answers

Link of the week Data Disaster Data Disaster - Use dedicated circuits for your connection - Keep your computer cool and in a dry place - Use a UPS (Uninterrupted Power Supply) - Don’t assume that your data is permanently destroyed

Link of the week Data Disaster - Big and small company operations - Backup services - Trouble shooting - Data recovery Define: Power Monkey Define: Thermal Logic Technology

Review week four lab assignment Shell Commands cat chmod cp date find grep mkdir more less rmdir rm sort sleep wc kill diff cd whence umask

Review week four lab assignment Shell Arithmetic expressions <=- less than or equal tp >=- greater than or equal to <- less than >- greater than ==- equal to !=- not equal to *- multiplication /- division +- addition -- subtraction Shell statements printf “string”- output a string of information echo $COUNTER- output content of the variable COUNTER printf $NUMBER- output content of the variable NUMBER NUMBER=$(($NUMBER-1)) - decrease NUMBER value by one $# - number of positional parameters $? - return value $$ - prosess id of this shell $! - bachground process id

Review week four lab assignment Shell Conditional Expression Primitives -r - true if file exists and is readable -w - true if file exists and is writable -x- true if file exists and is executable -f- true if file exists and is a file -d- true if file exists and is a directory -eq- true if value of exp1 and exp2 are equal -ne- true if value of exp1 and exp2 are not equal -gt- true if value of exp1 is greater than value of exp2 -ge- true if value of exp1 is greater than or equal to value of exp2 -lt- true if value of exp1 is less than value of exp2 -le- true if value of exp1 less than or equal to value of exp2 Shell Quoting ‘ …’- single literal quotes “…”- double quotes (interpolation allowed) `…`- single back ticks (command execution)

Review week four lab assignment Shell I/O Redirection < variable- read from file (cat < test_file) > variable- write to a file (cat > test_file) variable >> variable- append content of file_1 to the end of file_2 (cat file_1 >> file_2) Shell Syntax while [ … ] do … done if [ … ] then … fi if [ … ] then … elif … fi test –r “$test_file” test x+1 –gt y

Review week four lab assignment Perl Binary Arithmetic Operators +- addition ($a + $b) *- multiplication ($a * $b) %- modulus (remainder of $a divided by $b) **- exponentiation ($a raised to the power of $b) Perl Comparison Operators ==- equal !=- not equal <- less than >- greater than <=- less than or equal >=- greater than or equal  - comparison (0 if equal, 1 if $variable_1 greater, -1 if $variable_2 greater

Review week four lab assignment Perl Comparison Operators eq- equal ne- not equal lt- less than gt- greater than le- less than or equal ge- greater than or equal cmp- comparison (0 if equal, 1 if $variable_1 greater, -1 if $variable_2 greater Perl Conditional Expression Primitives -e $var- true if file $var exists -r $var- true if file $var is readable -w $var- true if file $var is writable -d $var- true if $var is a directory -f $var- true if file $var is a file -T $var- true if file $var is a text file

Review week four lab assignment Perl Quotes “ “ double-quotes ‘ ‘ single-quotes ` ` backtick-quotes Perl String Operators $arrayexp[0]=“string assignment”; (string assignment to zero element of array) $cmdexp=`ls –l`; (string output from a command) $charexp=‘b’; (string character assignment) $strexp=“string assignment”; (string assignment) $intexp=150; (an integer) $str_int=“I have two $pets”; (string with interpolation) Perl Commands chop unless print $var pop

Review week four lab assignment Perl Variable Syntax $ singular variables prefix (single value, number or prefix for plural variable (array) %prefix for plural variable (hash) $_ default variable Relational Operators Equality Operators

Review week four lab assignment Perl Syntax while ( … ) { … } If ( …) { … } If ( … ) { … } else { … }

Review week four lab assignment Perl Syntax ;end of statement delimiter,comma for line continuation \nnew line

Weeks four and five expected outcomes Write Perl scripts, including variables, control flow, and regular expression syntax

Next lab assignment Programming Perl, Chapter 32 Standard Modules Define: Module Parsing the command line with Getopt::Std Example: listdir –l –n –a 10:00 bottom top Perl to capture the command line arguments Example: $ARGV[0] ‘-l’ $ARGV[1]‘-n’ $ARGV[2]‘-a’ $ARGV[3]’10:00’ $ARGV[4]‘bottom’ $ARGV[5]‘top’

Next lab assignment Perl = (“rake”, “mower”, “shovel”); ($rake, $mower, $shovel) Perl Hash %colormap=( “12” => “gray”, “19” => “black”, “30” => “red”,); %colormap = (“12”, “gray”, “19”, “black”, “30”, “red”);

Break-out problems Global variable Boolean Binary Executable file Execute bit fork command Portable Object file System call Data structure

Upcoming deadlines Simple Perl Script, 5-1 is due 6/1/08. Makefile Exercise, 7-2 is due 6/15/08. Mid-term exam dates 6/9/08 through 6/14/08. Programming Assignment 1, 6-1 is due 6/22/08. -Script logic for the above assignment will be ed at the end of the week. Reading Assignment Essential System Administration Chapter One, pages 1 -8, 12 – 28 Chapter Two, pages 32 – 61 Chapter Three Programming Perl Chapter One Chapter Two, pages 47 – 65, 69 – 73, Chapter Three, pages 86 – 90, Chapter Thirty Two, pages 865 – 867, 899

Questions and answers Questions Comments Concerns After class I will help students with their scripts.