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Tutorial11: Sed & Awk Utilities

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{{Admon/caution|DO NOT USE THIS VERSION OF THE LAB. LOOK FOR LAB 10: SED & AWK|'''This is an archive version.'''}}
 
=USING SED & AWK UTILTIES=
<br>
:* Use the '''sed''' command to '''manipulate text''' contained in a file.
:* List and understand explain several '''addresses''' and '''instructions''' associated with the '''sed''' command.
:* Use the '''sed''' command as a '''filter''' with Linux pipeline commands.
:* Use the '''awk''' command to '''manipulate text''' contained in a file.
 
:* List and explain '''comparison operators''', '''variables''' and '''actions''' associated with the '''awk''' command.
:* Use the '''awk''' command as a '''filter''' with Linux pipeline commands.
<br><br>
 
===Tutorial Reference Material===
|- valign="top" style="padding-left:15px;"
|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/ULI101/uli101ULI101-Week11.1.pptx PPTX]</li><li>Week 11 Lecture 2 Notes:<br> [[Media:ULI101-Week11.2.pdf | PDF]] | [https://ictmatrix.senecacollege.ca/~murrayjason.saulcarman/uli101slides/ULI101-Week11.2.pptx PPTX]<br></li></ul>
| style="padding-left:15px;" |'''Text Manipulation:'''* [https://www.digitalocean.com/community/tutorials/the-basics-of-using-the-sed-stream-editor-to-manipulate-text-in-linux Purpose of using the sed utility]* [https://www.digitalocean.com/community/tutorials/how-to-use-the-awk-language-to-manipulate-text-in-linux Purpose of using the awk utility]
| style="padding-left:15px;" |Man Pages'''Commands:'''
* [https://man7.org/linux/man-pages/man1/sed.1p.html sed]
* [https://man7.org/linux/man-pages/man1/awk.1p.html awk]
|colspan="1" style="padding-left:15px;" width="30%"|'''Brauer Instructional Videos:'''<ul><li>[https://www.youtube.com/watch?v=npU6S61AIko&list=PLU1b1f-2Oe90TuYfifnWulINjMv_Wr16N&index=14 Using the sed Utility]</li><li>[https://www.youtube.com/watch?v=OV3XzjDYgJo&list=PLU1b1f-2Oe90TuYfifnWulINjMv_Wr16N&index=13 Using the awk Utility]</ul>
|}
'''NotesHow it Works:'''
*The sed command reads '''all reads all lines in the input file''' and file and will be exposed to the expression <br>(i.e. area contained in within quotes) one line at a time.* The expression can be within single quotes or double quotes.* The expression contains an address (match condition) and an instruction (operation).* If the line matches the address, then it will perform the instruction.* Lines will display be default unless the '''address–n''', then it will perform the option is used to suppress default display<br>'''instructionAddress:'''.
* Can use a line number, to select a specific line (for example: '''5''Address')* Can specify a range of line numbers (for example:'''5,7''')* Regular expressions are contained within forward slashes (e.g. /regular-expression/)* Can specify a regular expression to select all lines that match a pattern (e.g '''/^[0-9].*[0-9]$/''') * If NO address is present, the instruction will apply to ALL lines
*can use a '''line number''', to select a specific line
*can specify a '''range of line numbers'''
*can specify a '''regular expression''' to select all lines that match
*'''Note:''' when using regular expressions, you must delimit them with a<br>'''forward-slash''' "'''/'''" default address (if none is specified) will match every line
[[Image:sed.png|thumb|right|500px|'''Common instructions''' to take action if text matches an address.]]
'''Instruction:'''
*'''Action''' to take for matched line(s)
*Refer to table on right-side for list of some <br>'''common instructions'''<br>and their purpose  '''Examples:''' <span style="font-family:courier;">'''sed -n '3 p' text.txt''' (print 3rd line)<br>'''sed -n '1-5 p' text.txt''' (print lines 1 to 5)<br>'''sed -n '4,7 p' text.txt''' (print only lines 4 and 7)<br>'''sed -n'/^Therefore/ p' text.txt''' (print lines that begin with the patterh "Therefore")<br><br>'''sed '/^#/ d' myscript.bash''' (remove comments at beginning of line)<br>'''sed '/exit/ q' text.txt''' (print all lines until line containing pattern: "exit")<br>'''sed 's/this/that/' text.txt''' (replace first occurrence of pattern "this" with "that")<br>'''sed 's/this/that/' text.txt''' (replace ALL occurrences of pattern "this" with "that")<br><br></span>
===Using the awk Utility===
'''Usage:'''
<span style="color:blue;font-weight:bold;font-family:courier;">awk options [-F] 'selection _criteria -criteria {action }’ file-name</span>
'''NotesHow It Works:'''
*The '''awk command reads '''command reads all lines in the input file''' and will be exposed to the expression (contained within quotes) for processing.*Expression The '''expression''' (contained in quotes) represents '''selection criteria''', and '''action ''' to execute (contained within braces) '''{}'''* if selection criteria is matched *If no pattern is specified, awk selects all lines in the input*If no then action (between braces) is specified, awk copies the selected lines to standard outputexecuted.*You The '''–F''' option can use parameters like be used to specify the default '''$1field delimiter''', (separator) character<br>eg. '''$2awk –F”;”''' to represent first field, second field, etc (would indicate a semi-colon delimited input file).*You can use the <br>'''-FSelection Criteria''' option with the awk command to specify the field delimiter.
* You can use a regular expression, enclosed within slashes, as a pattern. For example: '''/pattern/'''
* The ~ operator tests whether a field or variable matches a regular expression. For example: '''$1 ~ /^[0-9]/'''
* The '''!~''' operator tests for no match. For example: '''$2 !~ /line/'''
* You can perform both numeric and string comparisons using relational operators ( '''>''' , '''>=''' , '''<''' , '''<=''' , '''==''' , '''!=''' ).
* You can combine any of the patterns using the Boolean operators '''||''' (OR) and '''&&''' (AND).
* You can use built-in variables (like NR or "record number" representing line number) with comparison operators.<br>For example: '''NR >=1 && NR <= 5'''
<br>
'''Action (execution):'''
* Action to be executed is contained within braces '''Patterns{}'''* 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''', '''$2''', '''$3''' … '''$9''' represent the first, second and third to the 9th fields contained within the record. * Parameters greater than nine requires the value of the parameter to be placed within braces (for example: Regular Expressions '''${10}''','''${11}''','''${12}''', etc.)* You can use built-in '''variables''' (such as '''NR''' or "record number" representing line number)<br>eg. '''{print NR,$0}''' (will print record number, then entire record).
*You can use a '''regular expression''', enclosed within slashes, as a pattern. *The '''~''' operator tests whether a field or variable matches a regular expression *The '''!~''' operator tests for no match.*You can perform both numeric and string comparisons using relational operators *You can combine any of the patterns using the Boolean operators '''||''' (OR) and '''&&''' (AND)*You can use '''built-in variables''' (like '''NR''' or "record number" representing line number) with comparison operators  [[Image:awk.png|thumb|right|300px|'''Comparison operators''' used with the '''awk''' command.]]'''Patterns: Relational Operators''' *The following operators (in the table on the right-side) can be used with the awk utility to pattern searching. *Since those symbols are used within the expression, they are NOT confused with redirection symbols.  '''Examples:''' <span style="font-familyINVESTIGATION 1:courier;">'''awk 'NR == 3 {print}' text.txt''' (print 3rd line)<br>'''awk 'NR >= 1 && NR <USING THE SED UTILITY= 5 {print}' text.txt''' (print lines 1 to 5)<br>'''awk '/NOTE:/ {print]' text.txt''' (print lines that contain the pattern: "NOTE:")<br><br>'''awk -F";" '$1 ~ /ford/ {print}' cars.dat''' (print records (of semi-colon delimited file) whose 1st field matches: "ford")<br>'''awk -F";" '$1 ~ /ford/ {print $2,$4}' cars.dat''' (same as above, but only print 2nd and 4th fields)<br><br></span>
<span style=INVESTIGATION 1"color: USING THE SED UTILITY=red;">'''ATTENTION''': 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>
<br>In this sectioninvestigation, you will learn how to manipulate text using the '''sed''' utility.
'''Perform the Following Steps:'''
# '''Login''' to your matrix accountand confirm you are located in your '''home''' directory.<br><br># Issue a Linux command to create a directory called '''confirmsed''' you are located in your home directory.<br><<br><br># Issue a Linux command to <u>change</u> to the following linux command ('''copy and pastesed''' to save time):directory and confirm that you are located in the '''sed''' directory.<br><span style="color:blue;font-weight:bold;font-familybr># Issue the following Linux command to download the data.txt file<br>('''copy and paste''' to save time):courier;"<br>wget <nowikispan 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 '''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><br><br># The [[Image:sed-1.png|thumb|right|300px|Issuing the '''p''' command in sed is used instruction without using the '''-n''' option (to print or suppress original output) will display the contents of a text filelines twice.]]<br><br>Issue The '''p''' instruction with the following linux '''sed''' command:is used to<br><span style="color:blue;font-weight:bold;font-family:courier;">sed 'p' data'print''' (i.e. ''display'') the contents of a text file.txt</span><br><br>You should notice that each line appears '''twice'''. The reason why standard output appears twice is that # Issue the sed following Linux command (without the '''-n option''') displays all lines regardless if they had been specified as a pattern.:<br><br># Issue the following linux command:<br><span stylespan style="color:blue;font-weight:bold;font-family:courier;">sed -n 'p' data.txt</span><br><br>What do you '''NOTE: You should notice?that each line appears twice'''.<br><br>You can specify an address (line #, line #s or range of line #s) when using The reason why standard output appears twice is that the sed utility.command<br><br># Issue (without the following linux command:'''-n option''') displays all lines regardless of an address used.<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n br>We will use ''1 p' data.txtpipeline commands''' to both display stdout to the screen and save to files</spanbr>for <bru>confirmation<br/u>You should see the first line of the text file displayedof running these pipeline commands when run a '''checking-script''' later in this investigation.<br><br># Issue the following linux Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '2,5 p' data.txt<| tee sed-1.txt</span><br><br>What is displayed? How do you change command to display lines 2 to 5notice?You should see only one line.<br><br>The You can specify an '''saddress''' command is used to substitute patterns (similar to method demonstratedin vi editor).display lines using the sed utility<br><br>(eg. ''line #'', '''line # Issue the following linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed s'''2,5 or range of '''line #s/TUTORIAL/LESSON/g' data'').txt</span><br><br>What do you notice? View # Issue the original contents of lines 2 to 5 in the 'following Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '1 p'data.txt''' file in another shell to confirm that the substitution occurred| tee sed-2.txt</span><br><br>The '''q''' command terminates or '''quits''' You should see the execution first line of the sed utility as soon as it read text file displayed.<br>What other command is used to only display the first line in a particular line or matching pattern.file?<br><br># Issue [[Image:sed-2.png|thumb|right|500px|Using the following linux sed command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed to display a '''11 qrange' data.txt</span>'' of lines.]]# Issue the following Linux pipeline command:<br><br>What did you notice?<brspan style="color:blue;font-weight:bold;font-family:courier;"><sed -n '2,5 p' data.txt | tee sed-3.txt</span><br>You can use regular expressions <br>What is displayed? How would you modify the sed command to select lines that match a pattern. The rules remain display the same for using regular expressions as demonstrated in lab8 except the regular expression must be contained within delimiters such as the forward slash "/" when using the sed utility.line range 10 to 50?<br><br>The '''s''' instruction is used to '''substitute''' text<br>(a similar to method was demonstrated in the vi editor in tutorial 9).<br><br># Issue the following linux Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '2,5 s/^TheTUTORIAL/LESSON/ pg' data.txt| tee sed-4.txt | more</span><br><br>What do you notice?<br><br># Issue View the following linux command:original contents of lines 2 to 5 in the '''data.txt''' file<br><span style="colorin another shell to confirm that the substitution occurred.<br><br>[[Image:blue;fontsed-weight:bold;font-family:courier;">3.png|thumb|right|500px|Using the sed command with the '''-n q''/d$/ p' dataoption to display up to a line number, then quit.txt</span><br><br>What do you notice?<br><br>The ]]The '''q''' instruction terminates or '''sedquits''' the execution of the sed utility can also be used as soon as it is read in a filter to manipulate text that was generated from linux commandsparticular line or matching pattern.<br><br># Issue the following linux Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">ls | sed -n '/11 q' data.txt | tee sed-5.txt$/ p'</span><br><br>What did you notice?How many lines were displayed<br>before the sed command exited?<br># Issue the following linux pipeline command:<br<br><span style="color:blue;font-weight:bold;font-family:courier;">who | sed -n You can use '''regular expressions'''/^[to select lines that match a-m]/ p' | morepattern. In fact,</spanbr>the sed command was one of the <bru>first<br/u> Linux commands that used regular expression.<br><br>What did you noticeThe rules remain the same for using regular expressions as demonstrated in '''tutorial 9'''<br>except the regular expression must be contained within '''forward slashes'''<br>(eg. <span style="font-family:courier;font-weight:bold;">/regexp/</span> ).<br><br>[[Image:sed-4.png|thumb|right|400px|Using the sed command using regular expressions with '''anchors'''.]]# Issue the following Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '/^The/ p' data.txt | tee sed-6.txt</span><br><br>What do you notice?<br><br># Issue the following Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '/d$/ p' data.txt | tee sed-7.txt</span><br><br>What do you notice?<br><br>The '''sed''' utility can also be used as a '''filter''' to manipulate text that<br>was generated from Linux commands.<br><br>[[Image:sed-5.png|thumb|right|400px|Using the sed command with '''pipeline''' commands.]]# 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;">~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>
=INVESTIGATION 2: USING THE AWK UTILITY =
In this sectioninvestigation, you will learn how to use the awk utility to manipulate text and generate reports. 
'''Perform the Following Steps:'''
# Issue Change to your '''home''' directory and issue a command to '''confirm''' <br>you are located in your ''home '' directory.<br><br># Issue a Linux command to create a directory called '''awk'''<br><br># Issue a Linux command to <u>change</u> to the '''awk''' directory and confirm you are located in the '''awk''' directory.<br><br>Let's download a database file that 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;">wget <nowiki>https://ict.senecacollege.ca/~murray.saul/uli101/cars.txt</nowiki></span><br><br>
# Issue the '''morecat''' command to quickly view the contents of the '''cars.txt''' file.<br>When finished, exit the more <br>The "'''print'''" action (command by pressing ) is the letter <span style="color:blue;font-weight:bold;font-family:courier;">qu>default</spanu>action of awk to print<br><br>The "all selected lines that match a '''printpattern'''" action (command) is the .<ubr>default</ubr> This '''action of awk to print all selected lines that match a pattern.<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 contain matches the pattern (or "make ") called '''ford"''':<br><span style="color:blue;font-weight:bold;font-family:courier;">wget awk '/ford/ {print}' cars.txt</span><br><br># Issue the following linux command all We will use '''pipeline commands''' to both display records in stdout to the "cars.txt" database that contain the make "ford":screen and save to files for <u>confirmation</u> of running these pipeline commands when run a '''checking-script''' later in this investigation.<br><span style="color:blue;font-weight:bold;font-family:courier;"br># Issue the following linux pipeline command all to display records<br>awk in the ''/ford/' cars.txt''' database that contain the pattern (i.e. make) '''ford''':</spanbr><brspan style="color:blue;font-weight:bold;font-family:courier;">awk '/ford/' cars.txt | tee awk-1.txt</span><br>What do you notice?<br><br>What do you notice? You can use variables with the "print" action for further processing. We will discuss the following variables in this tutorial:should notice ALL lines displayed <bru>without<br/u>using '''$0search criteria''' - Current record (entire line).<br><br>You can use ''builtin'$1''' - First field in record<br>'variables''$n'with the '' - nth field in record<br>'print''NR''' - Record Number (order in database)command for further processing.<br> '''NF''' - Number of fields We will discuss the following variables in current recordthis tutorial:<br><br>For a listing of more variables, please consult your course notes[[Image:awk-2.<br><br>The png|thumb|right|400px|Using the awk command to print search results by '''tilde characterfield number''' .]]'''~$0''' is used to search for a pattern or display standard output for a particular field.- Current record (entire line)<br>'''$1''' - First field in record<br># Issue the following linux command to display the model, year, quantity and price '''$n''' - nth field in the "cars.txt" database for makes of "chevy":record<br><span style="color:blue;font'''NR''' -weight:bold;font-family:courier;"Record Number (order in database)<br>awk '/chevy/ {print $2,$3,$4,$5}' cars.txt'NF''' - Number of fields in current record</spanbr><br>For a listing of more variables, please consult your course notes.<br>Notice that a space " " is the delimiter for the fields that appear as standard output.<br><br<br># Issue the following linux pipeline command to display all plymouths (plyms) by the '''model name''', '''year''', '''quantity''' and price and quantity:<br><span 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>You can also use comparison operators to specify conditions Notice that a '''space''' is the delimiter for processing with matched patterns when using the awk commandthe fields that appear as standard output. Since they are used WITHIN the awk expression, they are not confused with redirection symbols<br><br> Comparison Operators:<br><br><br><br>The '''tilde character'''<''' &nbsp;&nbsp;&nbsp;&nbsp;Less than<br>~'''<=''' &nbsp;&nbsp;Less than is used to search for a pattern or equaldisplay standard output for a particular field.<br>'''>''' &nbsp;&nbsp;&nbsp;&nbsp;Greater than<br<br># Issue the following linux pipeline command to display all '''plymouths'>=''(' &nbsp;&nbsp;Greater than or equal<br>''plym'==''' &nbsp;&nbsp;Equal)<br>by '''!=model name''' &nbsp;&nbsp;&nbsp;Not equal, '''price''' and '''quantity''':<br><brspan style="color:blue;font-weight:bold;font-family:courier;"># Issue the following linux command to display display the car makeawk '$1 ~ /plym/ {print $2,$3, model number$4, quantity and price of all vehicles that are prices less than $5,000:$5}' cars.txt | tee awk-3.txt</span><br><span style="color:blue;font-weight:bold;font-family:courier;">awk br>You can also use '''$5 comparison operators''' to specify conditions for processing with matched patterns< 5000 {print $1,$2,$4,$5}' carsbr>when using the awk command.txtSince they are used WITHIN the awk expression,</spanbr>they are not confused with redirection symbols<br><br>What do you notice?<br><br># Issue [[Image:awk-3.png|thumb|right|400px|Using the following linux awk command to display display the car make, model number, quantity and price of all vehicles that are prices less results based on '''comparison operators'''.]]'''<''' &nbsp;&nbsp;&nbsp;&nbsp;Less than $5,000:<br>'''<span style="color:blue''' &nbsp;font-weight:bold&nbsp;font-family:courier;"Less than or equal<br>awk '$5 < 5000 {print $1,$2,$4,$5}' cars.txt</span><br'>''' &nbsp;&nbsp;&nbsp;&nbsp;Greater than<br>The symbol tilde '''~>=''' is used to match a pattern for a particular field number.&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''', year '''model''', '''quantity''' and quantity of all car makes that begin with the letter 'f''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 ~ /^f/ {print ,$12,$24,$45}' cars.txt | tee awk-4.txt</span><br><br>Compound criteria symbols can be used to join search statements togetherWhat do you notice?<br><br>Compound Operators:<br># Issue the following linux pipeline command to display display '''price''',<br>'''&&quantity''', '''model''' &nbsp;&nbsp;&nbsp;&nbsp;(and)<br>'''||car make''' &nbspof vehicles whose '''prices are less than $5,000''':<br><span style="color:blue;&nbspfont-weight:bold;&nbspfont-family:courier;&nbsp;&nbsp;&nbsp;&nbsp;(or)<br><br>">awk '$5 < 5000 {print $5,$4,$2,$1}' cars.txt | tee awk-5.txt</span><br><br># Issue the following linux pipeline command to list all "fords" that are greater than $10display the '''car make''',000 in price:<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '$1 ~ /ford/ && $5 > 10000 {print $0}' 'year''' and '''quantity''' of cars.txt</span><br><br># After you complete that '''begin''' with the Review Questions sections to get additional practice, then work on your '''online assignment 3,letter 'f'''':<br>'''sections 4 to 6''' labelled<span style="color:blue;font-weight:bold;font-family: courier;">awk '''More Scripting (add)'''$1 ~ /^f/ {print $1, '''Yet More Scripting (oldfiles)'''$2, and $4}'''sed And cars.txt | tee awk-6.txt</span><br><br>[[Image:awk-4.png|thumb|right|400px|Using the awkcommand 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 save time):<br><span style="color:blue;font-weight:bold;font-family:courier;">wget <nowiki>https://ict.senecacollege.ca/~murray.saul/uli101/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>
= LINUX PRACTICE QUESTIONS =
Write the results of each of the following Linux commands for the above-mentioned file:
 # <span style="font-family:courier;font-weight:bold"># sed -n '3,6 p' ~murray.saul/uli101/stuff.txt</span><br><br># <span style="font-family:courier;font-weight:bold">sed '4 q' ~murray.saul/uli101/stuff.txt</span><br><br># <span style="font-family:courier;font-weight:bold">sed '/the/ d' ~murray.saul/uli101/stuff.txt</span><br><br># <span style="font-family:courier;font-weight:bold">sed 's/line/NUMBER/g' ~murray.saul/uli101/stuff.txt</span> 
'''Part B: Writing Linux Commands Using the sed Utility'''
# <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:bold">awk ‘$1 ~ /This/ {print $2}’ ~murray.saul/uli101/stuff.txt</span><br><br># <span style="font-family:courier;font-weight:bold">awk ‘$1 ~ /This/ {print $3,$2}’ ~murray.saul/uli101/stuff.txt</span><br><br>

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