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Tutorial11: Sed & Awk Utilities

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=INVESTIGATION 1: USING THE SED UTILITY=
<span style="color:red;">'''ATTENTION''': Depending on your ULI101 instructor, you may be required to complete this tutorial for '''marks''' in this course.<br>Please refer to your instructor's course notes and lecture notes regarding evaluation for this course.<br><br>The due date for successfully completing this tutorial (i.e. '''tutorial 11''') is by '''Friday by midnight''' next week (i.e. '''Week 11''').<br>If your instructor has NOT assigned marks for completing this tutorial, you can perform it for '''practice'''.</span><br><br> 
In this investigation, you will learn how to manipulate text using the '''sed''' utility.
# Issue the following Linux pipeline command:<br><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 pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">ls | sed -n '/txt$/ p' | tee sed-9.txt</span><br><br>What did you notice?<br><br>
# Issue the following to run a checking script:<br><span style="color:blue;font-weight:bold;font-family:courier;">bash /home/murray.saul/myscripts~uli101/week11-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 how to manipulate text using the '''awk''' utility.<br><br>
# Issue 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 display all lines (i.e. records) in the '''cars.txt''' database that matches the pattern (or "make") called '''ford''':<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '/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 display records<br>in the '''cars.txt''' database that contain the pattern (i.e. make) '''ford''':<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '/ford/' cars.txt | tee awk-1.txt</span><br><br>What do you notice? You should notice ALL lines displayed <u>without</u> using '''search criteria'''.<br><br>You can use these ''builtin'' '''variables''' with the '''print''' command for further processing.<br>We will discuss the following variables in this tutorial:<br><br>[[Image:awk-2.png|thumb|right|400px|Using the awk command 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 current record<br><br>For a listing of more variables, please consult your course notes.<br><br>
# Issue the following linux pipeline command to display the '''model''', '''year''', '''quantity''' and price<br>in the '''cars.txt''' database 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>Notice that a '''space''' is the delimiter for the fields that appear as standard output.<br><br>The '''tilde character''' '''~''' is 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 '''plymouths''' ('''plymsplym''')<br>by '''model name''', '''price''' and '''quantity''':<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '$1 ~ /plymsplym/ {print $2,$3,$4,$5}' cars.txt | tee awk-3.txt</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,<br>they are not confused with redirection symbols<br><br>[[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>'''>''' &nbsp;&nbsp;&nbsp;&nbsp;Greater than<br>'''>=''' &nbsp;&nbsp;Greater than or equal<br>'''==''' &nbsp;&nbsp;Equal<br>'''!=''' &nbsp;&nbsp;&nbsp;Not equal<br><br>
# Issue the following linux pipeline command to display display the '''car make''', '''model''', '''quantity''' and '''price''' of all vehicles whose '''prices are less than $5,000''':<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '$5 < 5000 {print $1,$2,$4,$5}' cars.txt | tee awk-4.txt</span><br><br>What do you notice?<br><br>
# Issue the following linux pipeline command to display display '''car make''',<br>'''model''', '''quantity''' and '''price''' of vehicles whose '''prices are less than $5,000''':<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '$5 < 5000 {print $1,$2,$4,$5}' cars.txt | tee awk-5.txt</span><br><br>
# Issue the following linux pipeline command to display the '''car 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'''.]]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>
# Issue the following 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 following linux command ('''copy and paste''' to run a checking scriptsave time):<br><span style="color:blue;font-weight:bold;font-family:courier;">bash wget <nowiki>https:/home/ict.senecacollege.ca/~murray.saul/myscriptsuli101/cars2.txt</nowiki></span><br><br># 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 '''cars2.txt''' database:<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 did you notice?<br><br>The problem is that the '''cars2.txt''' database separates each field by a semi-colon (''';''') <u>instead</u> of '''TAB'''.<br>Therefore, it does not recognize the second and fourth fields.<br><br>You need to issue awk with the -F option to indicate that this file's fields are separated (delimited) by a semi-colorn.<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 '''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 time?<br><br># Issue the following to run a checking script:<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''' the checking script until you<br>receive a congratulations message, then you can proceed.<br><br>
:: After you complete the Review Questions sections to get additional practice,<br>then work on your '''online assignment 3, section 2: Awk &amp; Sed'''<br><br>
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