Changes

=INTRODUCTION TO SHELL SCRIPTINGUSING SED & AWK UTILTIES=

:* Understand Use the process for '''planningsed''' prior command to writing '''manipulate text''' contained in a shell scriptfile.

:* Understand List and explain several '''addresses''' and '''instructions''' associated with the purpose of a '''she-bang linesed''' contained at the top of a shell scriptcommand.

:* Setting Use the '''permissionssed''' for command as a shell script and properly '''executefilter''' a shell scriptwith Linux pipeline commands.

:* Understand and use Use the '''environmentawk''' and command to '''user-defined''''''Bold manipulate text''' variables within contained in a shell scriptfile.

:* Understand List and explain '''comparison operators''', '''variables''' and '''actions''' associated with the purpose of '''control flow statementsawk''' used with shell scriptscommand.

:* Use the '''testawk''' command to test various conditions. :* Use the '''ifas a ''' logic statement and the filter'''for''' loop statement within shell scriptswith Linux pipeline commands.<br><br>

|colspan="2" |Course Notes'''Slides''':<ul><li>Week 11 Lecture 1 Notes:<br> [[Media:ULI101-Week11.1.pdf | PDF]] | [https://ictmatrix.senecacollege.ca/~murraychris.sauljohnson/uli101ULI101/ULI101-Week11.1.pptx PPTX]</li><li>Week 11 Lecture 2 Notes:<br> [[Media:ULI101-Week10Week11.2.pdf | PDF]] | [https://ictmatrix.senecacollege.ca/~murrayjason.saulcarman/uli101slides/ULI101-Week10Week11.2.pptx PPTX]<br></li></ul> 

| style="padding-left:15px;" |Shell Scripting* [https'''Commands://searchdatacenter.techtarget.com/definition/shell-script Purpose]'''* [https://wwwman7.youtube.comorg/watch?v=cQepf9fY6cE Creating and Running a Shell Script]<br>Variables* [https:linux//opensource.com/article/19/8/whatman-are-environment-variables Environment]* [https:pages/man1/wwwsed.linuxtechi.com/variables-in-shell-scripting/#:~:text=User%20Defined%20Variables%3A,like%20a%20real%20computer%20program. User Defined]Commands* [http://linuxcommand.org/lc3_man_pages/readh1p.html readsed]* [https://man7.org/linux/man-pages/man1/readonlyawk.1p.html readonlyawk]

|colspan="1" style="padding-left:15px;" width="30%"|'''Brauer Instructional Videos:'''<ul><li>[https://www.youtube.com/watch?v=kxEP-KUhOSgnpU6S61AIko&list=PLU1b1f-2Oe90TuYfifnWulINjMv_Wr16N&index=5 Introduction to Shell Scripting14 Using the sed Utility]</li><li>[https://www.youtube.com/watch?v=XVTwbINXnk4OV3XzjDYgJo&list=PLU1b1f-2Oe90TuYfifnWulINjMv_Wr16N&index=6 13 Using Variables and Control Flow Statements in Shell Scriptingthe awk Utility]</ul>

[[Image:ipso.png|thumb|right|500px|An '''IPSO Diagram''' (INPUT, PROCESSING, STORAGE, OUTPUT) can be used to map-out and then list the sequence of steps to assist when coding your shell script.]]It is recommended to '''plan''' out on a piece of paper the purpose of the shell script.<br>You can do this by creating a simple '''IPSO''' diagram (stands for '''INPUT''', '''PROCESSING''', '''STORAGE''', '''OUTPUTUsage:''').

'''Using a Shebang LineHow it Works:'''

[[Image:shebang.png|thumb|right|200px|* The '''shebang line''' <u>must</u> appear on sed command reads all lines in the '''first line''' and at the '''beginning''' of input file and will be exposed to the shell script.]]If you are learning Bash scripting by reading other people’s code you might have noticedexpression<br>that the first (i.e. area contained within quotes) one line in the scripts starts with the #! characters and the path to the Bash interpreterat a time.* The expression can be within single quotes or double quotes.This sequence of characters * The expression contains an address (#!match condition) and an instruction (operation) is called '''shebang''' and is used to tell the operating system<br>which interpreter to use to parse the rest of the file. Reference: https://linuxize.com/post/bash-shebang/ The '''shebang line''' <u>must</u> appear on * If the '''first line''' and at the '''beginning''' of the shell script,<br>otherwisematches the address, then it will be treated as a regular comment and ignoredperform the instruction. * Lines will display be default unless the '''Setting Permissions &amp; Running a Shell Script–n'''option is used to suppress default display To run your shell script by name, you need to assign '''execute permissions''' for the user.<br>To run the shell script, you can '''execute''' the shell script using a Address:''relative'', ''absolute'', or ''relative-to-home'' pathname

* Can use a line number, to select a specific line (for example: '''5''Example')* Can specify a range of line numbers (for example:<br><br><span style="font-family:courier;">chmod u+x myscript'''5,7''')* Regular expressions are contained within forward slashes (e.bash<br>g./myscript.bash<br>regular-expression/home/username/myscript)* Can specify a regular expression to select all lines that match a pattern (e.bash<br>~g '''/myscript^[0-9].bash<*[0-9]$/span>''') * If NO address is present, the instruction will apply to ALL lines

'''Definition''' ''<b>Variables</b> are used to '''store information''' to be referenced and manipulated in a computer program.<br>They also provide a way of labeling data with a descriptive name, so our programs can be understood<br>more clearly by the reader and ourselves.''<br>Reference: https://launchschool.com/books/ruby/read/variables  '''Environment Variables''' [[Image:environmentsed.png|thumb|right|500px|Examples of using '''Environment''' and '''User Defined''' variables.]]Shell '''environment variablesInstruction:''' shape the working environment whenever you are logged in Common shell. Some of these variables are displayed via Linux commands in the diagram displayed on the right-side.<br>(you can issue the pipeline command *'''set | moreAction''' to view all variablestake for matched line(s) Placing a dollar sign ('''$''') prior *Refer to the variable name will cause the variable to expand to the value contained in the variable.  '''User Defined Variables''' ''<b>Usertable on right-defined variablesside for list of some</bbr> are variables which can be '''created by the usercommon instructions''' and exist in the session. This means that no one can access user-defined variables that have been set by another user,<br>and when the session is closed these variables expire.''<br>Reference: https://mariadb.com/kb/en/user-defined-variables/their purpose

===Using Control Flow Statements in Shell Scriptsthe awk Utility===

The special parameter '''$?Usage:''' Is used to determine the '''exit status''' of the previously issued Linux command.The exit status will either display a '''zero''' (representing TRUE) or a '''non-zero''' number (representing FALSE). The test command can be used with control flow statements to control the sequence of a shell script.

You CANNOT use the '''<span style="color:blue;font-weight:bold;font-family:courier;">awk [-F] ''' or '''selection-criteria {action}’ file-name<''' symbols when using the test command since these are redirection symbols. Instead, you need to use options when performing numerical comparisons.Refer to the table below for test options and their purposes./span>

Refer to diagrams to the right involving some of the options used with the '''testHow It Works:''' command. Refer to the test man pages for a full list of options for the test command.

* The '''Logic Statementsawk''' command reads all lines in the input file and will be exposed to the expression (contained within quotes) for processing.*The '''expression''' (contained in quotes) represents '''selection criteria''', and '''action''' to execute contained within braces '''{}'''* if selection criteria is matched, then action (between braces) is executed.* The '''–F''' option can be used to specify the default '''field delimiter''' (separator) character<br>eg. '''awk –F”;”''' (would indicate a semi-colon delimited input file).<br>'''Selection Criteria'''

A * You can use a regular expression, enclosed within slashes, as a pattern. For example: '''logic statement/pattern/''' is used to determine which Linux commands to be executed based<br>on the result of * The ~ operator tests whether a field or variable matches a condition (iregular expression.e. TRUE (zero value) or FALSE (nonFor example: '''$1 ~ /^[0-zero value))9]/'''* The '''!~''' operator tests for no match.For example: '''$2 !~ /line/''' * You can perform both numeric and string comparisons using relational operators ( '''>''' , '''>=''' , '''<''' , '''<table align="right"><tr valign''' , '''==''' , '''!="top"><td>[[Image:logic-1''' ).png|thumb|right|250px|Example * You can combine any of the patterns using the Boolean operators '''||''' (OR) and '''if&&''' logic control(AND).* You can use built-flow statementin variables (like NR or "record number" representing line number) with comparison operators.]]</tdbr><td>[[ImageFor example:loop-1.png|thumb|right|250px|Example of using the '''forNR >=1 && NR <= 5''' looping control-flow statement.]]</td></tablebr>'''Action (execution):'''

There are several logic statements* Action to be executed is contained within braces '''{}'''* The '''print''' command can be used to display text (fields).* You can use parameters which represent fields within records (lines) within the expression of the awk utility.* The parameter '''$0''' represents all of the fields contained in the record (line).* The parameters '''$1''', but we will just concentrate on '''$2''', '''$3''' … '''$9''' represent the first, second and third to the 9th fields contained within the if statementrecord.<pre style=* Parameters greater than nine requires the value of the parameter to be placed within braces (for example: '''${10}''','''${11}''','''${12}''', etc.)* You can use built-in '''variables''' (such as '''NR''' or "width:20%record number"representing line number)<br>if test conditioneg. '''{print NR,$0}''' (will print record number, then command(sentire record) fi</pre>.

<span style="color:red;">'''Loop StatementsATTENTION''': Effective '''May 9, 2022''' - this online tutorial will be required to be completed by '''Friday in week 11 by midnight'''<br>to obtain a grade of '''2%''' towards this course</span><br><br>

''A <b>loop statement</b> is a series of steps or sequence of statements executed repeatedly zero or more times satisfying the given condition is satisfied.''<br>Reference: https://www.chegg.com/homework-help/definitions/loop-statement-3 There are several loops, but we will look at the '''for loop''' using a '''list'''. <pre style="width:20%">for item in list do command(s) done</pre> Refer to the diagram above and to the extreme right side for an example using the '''for loop''' with a '''list'''. =INVESTIGATION 1: CREATING A SHELL SCRIPT= <br>In this sectioninvestigation, you will learn how to create and run a manipulate text using the '''simple Bash Shell scriptsed'''utility.

# '''Login''' to your matrix accountand confirm you are located in your '''home''' directory.<br><br># Issue a Linux command to create a directory called '''sed'confirm''<br><br># Issue a Linux command to <u>change</u> to the '''sed''' directory and confirm that you are located in your home the '''sed''' directory.<br><br>We want # Issue the following Linux command to create a Bash Shell script to welcome download the user by their usernamedata. Lettxt file<br>(''s first provide some useful tips in terms'copy and paste''' to save time):<br>of selecting an appropriate name for the shell script<span style="color:blue;font-weight:bold;font-family:courier;">wget <nowiki>https://ict.senecacollege.ca/~murray.saul/uli101/data.txt</nowiki></span><br><br># Issue the following linux '''more''' command to quickly view the contents of the '''data.txt''' file.<br>When finished, exit the more command by pressing the letter <span style="color:blue;font-weight:bold;font-family:courier;">q</span>[[Image:sed-1.png|thumb|right|300px|Issuing the '''p''' instruction without using the '''-n''' option (to check if your intended shell script namesuppress original output) will display lines twice.]]<br><br>The '''p''' instruction with the '''sed''' command is already exists used to be run automatically from <br>'''print''' (i.e. ''display'') the contents of a text file.<br><br># Issue the Bash shellfollowing Linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">which hellosed 'p' data.txt</span><br><br>'''NOTE: You should notice that there is no output and therefore, this shell script name can be usedeach line appears twice'''.<br>On <br>The reason why standard output appears twice is that the other hand, if you wanted to create a file called sed, then command<br>(without the '''which sed-n option''' command) displays all lines regardless of an address used.<br><br>would indicate it is already being used by We will use '''pipeline commands''' to both display stdout to the shell screen and that save to files<br>for <u>confirmation</u> of running these pipeline commands when run a '''sedchecking-script''' wouldn't be an appropriate shell script name to uselater in this investigation.<br><br># Use a Issue the following Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n 'p' data.txt | tee sed-1.txt</span><br><br>What do you notice? You should see only one line.<br><br>You can specify an '''text editoraddress''' like vi or nano to create display lines using the text file called hello sed utility<br>(eg. ''line #'', '''line #s''' or range of '''line #s'''). <br><br># Issue the following Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">vi hellosed -n '1 p' data.txt | tee sed-2.txt</span>)<br><br>If you are using You should see the first line of the nano text editorfile displayed.<br>What other command is used to only display the first line in a file?<br><br>[[Image:sed-2.png|thumb|right|500px|Using the sed command to display a '''range''' of lines.]]# Issue the following Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '2, refer 5 p' data.txt | tee sed-3.txt</span><br><br>What is displayed? How would you modify the sed command to notes on display the line range 10 to 50?<br><br>The '''s''' instruction is used to '''substitute''' text editing in <br>(a previous week similar to method was demonstrated in the course schedulevi editor in tutorial 9).<br><br># Enter Issue the following two Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed '2,5 s/TUTORIAL/LESSON/g' data.txt | tee sed-4.txt | more</span><br><br>What do you notice? View the original contents of lines 2 to 5 in your the '''data.txt''' file<br>in another shell script, replacing "yourto confirm that the substitution occurred.<br><br>[[Image:sed-username" 3.png|thumb|right|500px|Using the sed command with your actual namethe '''-q''' option to display up to a line number, then quit.]]The '''q''' instruction terminates or '''quits''' the execution of the sed utility as soon as it is read in a particular line or matching pattern.<br><br># Issue the following Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">clear<br>echo "Hello yoursed '11 q' data.txt | tee sed-username"5.txt</span><br><br># Save your editing session and exit What did you notice? How many lines were displayed<br>before the text editor (eg. with vi: press sed command exited?<br><br>You can use '''ESCregular expressions'''to select lines that match a pattern. In fact, then type <br>the sed command was one of the <u>first</u> Linux commands that used regular expression.<br><br>The rules remain the same for using regular expressions as demonstrated in ''':wxtutorial 9''' followed by <br>except the regular expression must be contained within '''ENTERforward slashes'''<br>(eg. <span style="font-family:courier;font-weight:bold;">/regexp/</span> ).<br><br>[[Image:sed-4.png|thumb|right|400px|Using the sed command using regular expressions with '''anchors'''.]]# Issue the following linux Linux pipeline command to run your shell script in your current directory:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '/^The/ p' data.txt | tee sed-6.txt</hellospan><br><br>What do you notice?<br><br># Issue the following Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '/d$/ p' data.txt | tee sed-7.txt</span><br><br>You should What do you notice an error indicating you don?<br><br>The '''sed''' utility can also be used as a '''filter'''t have permissions to run manipulate text that<br>was generated from Linux commands.<br><br>[[Image:sed-5.png|thumb|right|400px|Using the filesed command with '''pipeline''' commands.]]# Issue the following Linux pipeline command:<br>You need to first add execute permissions prior to running the shell script<span style="color:blue;font-weight:bold;font-family:courier;">who | sed -n '/^[a-m]/ p' | tee sed-8.txt | more</span><br><br>What did you notice?<br><br># Issue the following linux Linux pipeline command to add execute permissions for your shell script:<br><span style="color:blue;font-weight:bold;font-family:courier;">chmod u+x hellols | sed -n '/txt$/ p' | tee sed-9.txt</span><br><br>What did you notice?<br><br># Re-Issue the following to run your shell a checking script: <br><span style="color:blue;font-weight:bold;font-family:courier;">.~uli101/helloweek11-check-1</span><br><br>If you encounter errors, make corrections and '''re-run''' the checking script<br>until you receive a congratulations message, then you can proceed.<br><br>

::In the next investigation, you will learn to create and run shell scripts that<br >use variables, positional and special parameters. You will also learn<br>how to add a manipulate text using the '''she-bang lineawk''' at the top of a shell script to force it to run in a specified shellutility.<br><br> =INVESTIGATION 2: USING VARIABLES IN SHELL SCRIPTS = In this section, you will learn how to use variables, positional and special parameters to assist you in creating adaptable shell scripts.

# Use Change to your '''home''' directory and issue a command to '''confirm'''<br>you are located in your ''home'' directory.<br><br># Issue a text editor Linux command to edit the shell script create a directory called '''hello.bashawk'''<br><br># Add the following line Issue a Linux command to <u>change</u> to the bottom of '''awk''' directory and confirm you are located in the '''awk''' directory.<br><br>Let's download a database filethat contains information regarding classic cars.<br><br># Issue the following linux command ('''copy and paste''' to save time):<br><span style="color:blue;font-weight:bold;font-family:courier;">echo "The current shell you are using iswget <nowiki>https: $SHELL"//ict.senecacollege.ca/~murray.saul/uli101/cars.txt</nowiki></span><br><br># Save your editing changes and exit your text editorIssue the '''cat''' command to quickly view the contents of the '''cars.txt''' file.<br><br>The "'''print'''" action (command) is the <u>default</u> action of awk to print<br>all selected lines that match a '''pattern'''.<br><br>This '''action''' (contained in braces) can provide more options<br>such as printing '''specific fields''' of selected lines (or records) from a database.<br><br>[[Image:awk-1.png|thumb|right|400px|Using the awk command to display matches of the pattern '''ford'''.]]# Issue the following linux command all to change to display all lines (i.e. records) in the '''cars.txt''' database that matches the Bourne Shell pattern (a different shell than the default Bashor "make")called '''ford''':<br><span style="color:blue;font-weight:bold;font-family:courier;">shawk '/ford/ {print}' cars.txt</span><br><br>We will use '''pipeline commands''' to both display stdout to the screen and save to files for <u>confirmation</u> of running these pipeline commands when run a '''checking-script''' later in this investigation.<br><br># Issue the following linux pipeline command all to confirm you are display records<br>in the Bourne Shell'''cars.txt''' database that contain the pattern (i.e. make) '''ford''':<br><span style="color:blue;font-weight:bold;font-family:courier;">echo $SHELLawk '/ford/' cars.txt | tee awk-1.txt</span><br><br>What do you notice? You should see notice ALL lines displayed <u>without</u> using '''search criteria'''.<br><br>You can use ''builtin'' '''variables''' with the '''print''' command for further processing.<br>We will discuss the output of following variables in this tutorial:<br><br>[[Image:awk-2.png|thumb|right|400px|Using the awk command that you are located to print search results by '''field number'''.]]'''$0''' - Current record (entire line)<br>'''$1''' - First field in record<br>'''$n''' - nth field in record<br>'''NR''' - Record Number (order in database)<br> '''NF''' - Number of fields in the Bourne Shellcurrent record<br><br>For a listing of more variables, please consult your course notes.<br><br># Run your Issue the following linux pipeline command to display the '''model''', '''year''', '''quantity''' and price<br>in the '''hellocars.bashtxt''' shell scriptdatabase for makes of '''chevy''':<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '/chevy/ {print $2,$3,$4,$5}' cars.txt | tee awk-2.txt</span><br><br>What shell does Notice that a '''space''' is the delimiter for the shell script indicate is running?fields that appear as standard output.<br><br>This is because there is NO The '''tilde character''' '''she-bang line~''' at the top of the shell script; therefore, it is being run in used to search for a pattern or display standard output for a particular field.<br><br># Issue the following linux pipeline command to display all '''Bourne Shellplymouths''' (i'''plym''')<br>by '''model name''', '''price''' and '''quantity''':<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '$1 ~ /plym/ {print $2,$3,$4,$5}' cars.txt | tee awk-3.etxt</span><br><br>You can also use '''comparison operators''' to specify conditions for processing with matched patterns<br>when using the awk command. Since they are used WITHIN the awk expression,<ubr>they are not confused with redirection symbols<br>current shell</ubr>)[[Image:awk-3.png|thumb|right|400px|Using the awk command to display results based on '''comparison operators'''.]]'''<''' &nbsp;&nbsp;&nbsp;&nbsp;Less than<br>'''<=''' &nbsp;&nbsp;Less than or equal<br>Let's ''>''' &nbsp;&nbsp;&nbsp;&nbsp;Greater than<br>'''>=''' &nbsp;&nbsp;Greater than or equal<br>'''add==''' a &nbsp;&nbsp;Equal<br>'''she-bang line!=''' &nbsp;&nbsp;&nbsp;Not equal<br><br># Issue the following linux pipeline command to display display the top '''car make''', '''model''', '''quantity''' and '''price''' of this shell script file so it all vehicles whose '''prices are less than $5,000''':<br><uspan style="color:blue;font-weight:bold;font-family:courier;">forcesawk '$5 < 5000 {print $1,$2,$4,$5}' cars.txt | tee awk-4.txt</uspan><br><br>What do you notice?<br><br> # Issue the shell script following linux pipeline command to run in the display display '''price''',<br>'''quantity''', '''model''' and '''Bash Shellcar make''' instead of the Bourne Shellvehicles whose '''prices are less than $5,000''':<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '$5 < 5000 {print $5,$4,$2,$1}' cars.txt | tee awk-5.txt</span><br><br># Use a text editor Issue the following linux pipeline command to edit display the shell script called '''hellocar make''',<br>'''year''' and '''quantity''' of cars that '''begin''' with the '''letter 'f'''':<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '$1 ~ /^f/ {print $1,$2,$4}' cars.txt | tee awk-6.txt</span><br><br>[[Image:awk-4.png|thumb|right|400px|Using the awk command to display combined search results based on '''compound operators'''.bash]]Combined pattern searches can be made<br>by using '''compound operator''' symbols:<br><br>'''&&''' &nbsp;&nbsp;&nbsp;&nbsp;(and)<br>'''||''' &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(or)<br><br># Add Issue the following line linux pipeline command to list all '''fords'''<br>whose '''price is greater than $10,000''':<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '$1 ~ /ford/ && $5 > 10000 {print $0}' cars.txt | tee awk-7.txt</span><br><br># Issue the TOP of the filefollowing linux command ('''copy and paste''' to save time):<br><span style="color:blue;font-weight:bold;font-family:courier;">#!wget <nowiki>https://ict.senecacollege.ca/~murray.saul/binuli101/bashcars2.txt</nowiki></span><br><br># Run your Issue the '''cat''' command to quickly view the contents of the '''cars2.txt''' file.<br><br># Issue the following linux pipeline command to display the '''year'''<br>and '''quantity''' of cars that '''begin''' with the '''letter 'f'''' for the '''hellocars2.bashtxt''' shell scriptdatabase:<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '$1 ~ /^f/ {print $2,$4}' cars2.txt | tee awk-8.txt</span><br><br>What shell does the shell script indicate is runningdid you notice?<br><br>This The problem is because that the '''cars2.txt''' database separates each field by a semi-colon (''';''') <u>instead</u> of '''TAB'''.<br>Therefore, it does not recognize the shebang line indicating to run the shell script in the Bash shell although you ran this script within the Bourne Shellsecond and fourth fields.<br><br>LetYou need to issue awk with the -F option to indicate that this file's add fields are separated (delimited) by a shesemi-bang line colorn.<br><br># Issue the following linux pipeline command to display the top '''year'''<br>and '''quantity''' of cars that '''begin''' with the '''letter 'f'''' for the '''cars2.txt''' database:<br><span style="color:blue;font-weight:bold;font-family:courier;">awk -F";" '$1 ~ /^f/ {print $2,$4}' cars2.txt | tee awk-9.txt</span><br><br>What did you notice this shell script file so it forces time?<br><br># Issue the shell following to run a checking script to :<br><span style="color:blue;font-weight:bold;font-family:courier;">~uli101/week11-check-2</span><br><br>If you encounter errors, make corrections and '''re-run in ''' the Bash Shell instead of the Bourne Shellchecking script until you<br>receive a congratulations message, then you can proceed.<br><br>

# Enter the following linux command to return to your Bash shell: <span style="color:blue;font-weight:bold;font-family:courier;">exit</span><br><br># Use Here is a text editor link to edit the shell script called '''hello.bash'''<br><br># Add the following lines to the bottom MS Word Document of the file:<br><span style="font-family:courier;">echo "The current username is: $USER"<br>echo "The current directory location is: $PWD"<br>echo "The current user's home directory is: $HOME</span><br><br># Save your editing changes and exit your text editor.<br><br># Run your '''hello.bash''' shell script.<br><br>Take time to view the output and the values ALL of the environment variables.<br><br># Issue the following linux command to add your current directory to the PATH environment variable:<br><span style="color:blue;font-weight:bold;font-family:courier;">PATH=$PATH:.</span><br><br># Issue the following linux command to confirm that the current directory "." has been added to the PATH environment variable:<br><span style="color:blue;font-weight:bold;font-family:courier;">echo $PATH</span><br><br># Run the '''hello.bash''' by just shell script name (i.e. to not use ./ prior questions displayed below but with extra room to shell script name).<br><br>The shell script should run just by name.<br><br># Exit your Matrix session, and log back into your Matrix session.<br><br># Re-run answer on the '''hello.bash''' shell script by just using the name.<br><br>What did you notice?<br><br>The setting of the PATH variable only worked in the current session only. If exit the current Matrix session, then the recently changed settings for environment variables are lost. You will learned in Week 12 how document to set environment variables in startup files.<br><br># Use simulate a text editor to create a file called '''user-variables.bash'''<br><br># Add the following lines to the bottom of the filequiz:<br><span style="font-family:courier;">#!/bin/bash<br>age=25<br>readonly age<br>read -p "Enter your Full Name" name<br>read -p "Enter your age (in years): " age<br>echo "Hello $name - You are $age years old"</span><br><br># Save your editing changes and exit your text editor.<br><br># Issue the '''chmod''' command to add execute permissions for the user for the '''user-variables.bash''' file.<br><br># Issue the following to run the user-variables.bash Bash shell script:<br><span style="color:blue;font-weight:bold;font-family:courier;">./user-variables.bash</span><br><br>What do you notice when you try to change the age variable? Why?<br><br># Use a text editor to create a file called '''parameters.bash'''<br><br># Add the following lines to the bottom of the file:<br><span style="font-family:courier;">#!/bin/bash<br>echo \$0: $0<br>echo \$2: $2<br>echo \$3: $3<br><br>echo \$#: $#<br>echo \$*: $*<br><br>shift 2<br>echo \$#: $#<br>echo \$*: $*</span><br><br># Save your editing changes and exit your text editor.<br><br># Issue the '''chmod''' command to add execute permissions for the user for the '''parameters.bash''' file.<br><br># Issue the following to run the '''user-variables.bash''' Bash shell script:<br><span style="color:blue;font-weight:bold;font-family:courier;">./parameters.bash</span><br><br>What happened?<br><br>The values for the parameters may not be displayed properly since you did NOT provide any arguments when running the shell script.<br><br># Issue the following to run the user-variables.bash Bash shell script with arguments:<br><span style="color:blue;font-weight:bold;font-family:courier;">./parameters.bash 1 2 3 4 5 6 7 8</span><br><br>Take some time to view the results and how the parameters are changed when using the shift command. What do you notice?

In Your instructor may take-up these questions during class. It is up to the student to attend classes in order to obtain the next investigation, you answers to the following questions. Your instructor will use controlNOT provide these answers in any other form (eg. e-flow statements to allow your shell scripts to perform differently under different situationsmail, etc).

'''Perform <pre>Line one.This is the Following Steps:'''second line.This is the third.This is line four.Five.Line six followsFollowed by 7Now line 8and line nineFinally, line 10</pre>

Write the results of each of the following Linux commands for the above-mentioned file: Before learning about logic and loop control-flow statements, you need to first learn about issuing test conditions using the '''test''' command.

# Issue the following linux commands to assign values to several variables:<br><span style="color:blue;font-weight:bold;font-family:courier;">course="ULI101"<br>number1=5<br>number2=10</span><br><br># Issue the following linux command to test a condition:<br><span style="color:blue;font-weight:bold;font-family:courier;">test $course = "ULI101"</span><br><br>The '''$?''' variable is used to store an exit status of the previously command issued (including the test command). If the status is zero, then it indicates a TRUE value and if the status is non-zero, then it indicates a FALSE value.<br><br># Issue the following linux command to view the status of the previouslysed -issued n '''test''' command:<br><span style="color:blue;font-weight:bold;font-family:courier;">echo $?</span><br><br>Based on its value3, is the result TRUE or FALSE?<br><br># Issue the following linux command to test another condition:<br><span style="color:blue;font-weight:bold;font-family:courier;">test $course = "uli101"</span><br><br># Issue the following linux command to view the status of the previously-issued 6 p'''test''' command:<br><span style="color:blue;font-weight:bold;font-family:courier;">echo $?<~murray.saul/span><br><br>The value is non-zero (FALSE) since UPPERCASE characters are different than lowercase characters.<br><br># Issue the following linux command to test another condition:<br><span style="color:blue;font-weight:bold;font-family:courier;">test $course != "uli101"</span><br><br># Issue a linux command to display the value of '''$?'''stuff. What is the result? Why?<br><br># Issue the following linux command to test a condition involving numbers:<br><span style="color:blue;font-weight:bold;font-family:courier;">test $number1 > $number2txt</span><br><br># Issue a linux command to display the value of '''$?'''. '''NOTE:''' You will notice that something is '''wrong'''.<br>The exit status '''$?''' shows a zero (TRUE) value, but the number 5 is definitely NOT greater than 10.<br>The problem is that the symbols '''&lt;''' and '''&gt;''' are interpreted as REDIRECTION symbols!<br><br># To prove this, issue the following linux command :<br><span style="color:blue;font-weight:bold;font-family:courier;">ls 10</span><br><br>You should notice a file called "'''10'''". The incorrectly issued '''test''' command used redirect to create an empty file instead,<br> which indeed succeeded just giving a TRUE value!<br><br>To prevent these incorrectly issued testing for number comparison, you can use the following options instead:<br>'''-lt''' (&lt;), '''-le''' (&lt;&#61;), '''-gt''' (&gt;), '''-ge''' (&gt;&#61;;), '''-eq''' (&#61;), '''-ne''' (!&#61;)<br><br># Issue the correct linux command to properly test both values:<br><span style="color:blue;font-weight:bold;font-family:courier;">test $number1 -gt $number2</span><br><br># Issue a linux command to display the value of '''$?'sed '4 q'~murray. You should notice that the exit status value is now FALSE which is the correct result.<br><br># The '''test''' command can be abbreviated by the square brackets &#91; &#93; which contain the test condition within the square brackets. You need to have spaces between the brackets and the test condition; otherwise, you will get a test error.<br><br># To generate a test error, issue the improper use of the '''test''' command:<br><span style="color:blue;font-weight:bold;font-family:courier;">&#91;$number1 -gt $number2&#93;<saul/span><br><br>You should notice an test error message.<br><br># Issue the correct use of the '''test''' command:<br><span style="color:blue;font-weight:bold;font-family:courier;">&#91; $number1 -gt $number2 &#93;<uli101/span><br><br>Issue a command to view the value of the exit status of the previously issued '''test''' command. You should notice that is works properlystuff.<br><br>'''Let's now learn about control-flow statements:'''<br><br>'''Logic statements''' are to create different paths or directions that the script can execute based in the result of testing conditions. In this tutorial, we will only focus on the '''if''' logic statement.<br><br># Use a text editor like vi or nano to create the text file called '''if-1.bash''' (eg. <span style="color:blue;font-weight:bold;font-family:courier;">vi if-1.bashtxt</span>)<br><br>If you are using the nano text editor, refer to notes on text editing in a previous week in the course schedule.<br><br># Enter the following lines in your shell script:<br><span style="font-family:courier;">#!/bin/bash<br>clear<br>num1=5<br>num2=10<br>if [ $num1 -gt $num2 ]<br>then<br>&nbsp;&nbsp;&nbsp;echo "Greater Than"<br>fi</span><br><br># Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':wx''' followed by '''ENTER''').<br><br># Issue the following linux command to add execute permissions for your shell script:<br><span style="color:blue;font-weight:bold;font-family:courier;">chmod u+x if-1.bash</span><br><br># Run your shell script by issuing: <span style="color:blue;font-weight:bold;font-family:courier;">./if-1.bash</span><br><br>Confirm that the output indicated a correct result.<br><br># Use a text editor like vi or nano to create the text file called '''if-2.bashsed ''' (eg. <span style="color:blue;font-weight:bold;font-family:courier;">vi if-2.bash</span>)<br><br>If you are using the nano text editor, refer to notes on text editing in a previous week in the course schedule.<br><br># Enter the following lines in your shell script:<br><span style="font-family:courier;">#!/bin/bash<br>clear<br>read -p "Enter the first number: " num1<br>read -p "Enter the second number: " num2<br>if [ $num1 -gt $num2 ]<br>then<br>&nbsp;&nbsp;&nbsp;echo "The first number is greater than the second number."<br>fi</span><br><br># Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':wx''' followed by 'd''ENTER''').<br><br># Issue the following linux command to add execute permissions for your shell script:<br><span style="color:blue;font-weight:bold;font-family:courier;">chmod u+x if-2~murray.bash<saul/span><br><br># Run your shell script by issuing: <span style="color:blue;font-weight:bold;font-family:courier;">.uli101/if-2.bash</span><br><br>Confirm that the output indicated a correct result.<br><br>What happens when you enter a first number that is less than or equal to the second number? We will learn about if-else and if-elif-else statements in a couple of weeks.<br><br>'''Loop statements''' are used to provide repetition in a shell script. In this tutorial, we will only focus on the '''for''' loop statement.<br><br># Use a text editor like vi or nano to create the text file called '''for-1.bash''' (eg. <span style="color:blue;font-weight:bold;font-family:courier;">vi for-1.bash</span>)<br><br>If you are using the nano text editor, refer to notes on text editing in a previous week in the course schedulestuff.<br><br># Enter the following lines in your shell script:<br><span style="font-family:courier;">#!/bin/bash<br>clear<br>for 5 4 3 2 1<br>do<br>&nbsp;&nbsp;&nbsp;echo $x<br>done<br>echo "blast-off!"txt</span><br><br># Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':wx''' followed by '''ENTER''').<br><br># Issue the following linux command to add execute permissions for your shell script:<br><span style="color:blue;font-weight:bold;font-family:courier;">chmod u+x for-1.bash</span><br><br># Run your shell script by issuing: <span style="color:blue;font-weight:bold;font-family:courier;">./for-1.bash</span><br><br># Use a text editor like vi or nano to create the text file called sed '''for-2.bash''' (eg. <span style="color:blue;font-weight:bold;font-family:courier;">vi for-2.bash</span>)<br><br>If you are using the nano text editor, refer to notes on text editing in a previous week in the course schedule.<br><br># Enter the following lines in your shell script:<br><span style="font-family:courier;">#!s/binline/bash<br>clear<br>for x<br>do<br>&nbsp;&nbsp;&nbsp;echo $x<br>done<br>echo "blast-off!"<NUMBER/span><br><br># Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type g''':wx''' followed by '''ENTER''')~murray.<br><br># Issue the following linux command to add execute permissions for your shell script:<br><span style="color:blue;font-weight:bold;font-family:courier;">chmod u+x for-2.bash<saul/span><br><br># Run your shell script by issuing: <span style="color:blue;font-weight:bold;font-family:courier;">.uli101/for-2stuff.bash 10 9 8 7 6 5 4 3 2 1txt</span><br><br>How does this differ from the previous shell script?<br><br>You will learn in a couple of weeks more examples of using loop statements.<br><br># After you complete the Review Questions sections to get additional practice, then work on your '''online assignment 3''',<br>'''sections 2 and 3''' labelled '''Interactive Shell Environment''' and '''Introduction To Scripting (phone)'''.<br><br>

The purpose of this section is to obtain '''extra practicePart B: Writing Linux Commands Using the sed Utility''' to help with '''quizzes''', your '''midterm''', and your '''final exam'''.

Here is Write a link single Linux command to perform the MS Word Document of ALL specified tasks for each of the following questions displayed below but with extra room to answer on the document tosimulate a quiz:.

Your instructor may take-up these questions during class# Write a Linux sed command to display only lines 5 to 9 for the file: '''~murray. It is up saul/uli101/stuff.txt'''<br><br># Write a Linux sed command to display only lines the student begin the pattern “and” for the file: '''~murray.saul/uli101/stuff.txt'''<br><br># Write a Linux sed command to attend classes in order display only lines that end with a digit for the file: '''~murray.saul/uli101/stuff.txt'''<br><br># Write a Linux sed command to obtain save lines that match the answers to pattern “line” (upper or lowercase) for the following questionsfile: '''~murray.saul/uli101/stuff. Your instructor will NOT provide these answers in any other form txt''' and save results (eg. e-mail, etcoverwriting previous contents)to: '''~/results.txt'''<br><br>

'''Review QuestionsPart C:Writing Linux Commands Using the awk Utility'''

'''PART B# <span style="font-family:courier;font-weight:bold">awk ‘NR == 3 {print}’ ~murray.saul/uli101/stuff.txt</span><br><br># <span style="font-family:courier;font-weight:bold">awk ‘NR >= 2 && NR <= 5 {print}’ ~murray.saul/uli101/stuff.txt</span><br><br># <span style="font-family:courier;font-weight: WALKbold">awk ‘$1 ~ /This/ {print $2}’ ~murray.saul/uli101/stuff.txt</span><br><br># <span style="font-THRUS'''family:courier;font-weight:bold">awk ‘$1 ~ /This/ {print $3,$2}’ ~murray.saul/uli101/stuff.txt</span><br><br>

:'''Walkthru #1Part D:Writing Linux Commands Using the awk Utility'''

:WRITE OUTPUT FROM ISSUING::'''Write a single Linux command to perform the specified tasks for each of the following questions./walkthru1.bash'''

# Write a Linux awk command to display all records for the file: '''~/cars''' whose fifth field is greater than 10000.<br><br># Write a Linux awk command to display the first and fourth fields for the file:'''Walkthru ~/cars''' whose fifth field begins with a number.<br><br>#2Write a Linux awk command to display the second and third fields for the file:'''~/cars''' for records that match the pattern “chevy”.<br><br># Write a Linux awk command to display the first and second fields for all the records contained in the file: '''~/cars'''<br><br>