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→INVESTIGATION 2: USING THE AWK UTILITY
# 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 without using a search criteria.<br><br>You can use these '''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>
# Issue the following linux pipeline command to display all plymouths (plyms) by model name, price and quantity:<br><span style="color:blue;font-weight:bold;font-family:courier;">awk '/chevy/ {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 when using the awk command. Since they are used WITHIN the awk expression, they are not confused with redirection symbols<br><br> Comparison Operators:<br><br>'''<''' Less than<br>'''<=''' Less than or equal<br>'''>''' Greater than<br>'''>=''' Greater than or equal<br>'''==''' Equal<br>'''!=''' Not equal<br><br>
# Issue the following linux pipeline command to display display the car make, model number, quantity and price of all vehicles that are prices 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 the car make, model number, quantity and price of all vehicles that are prices 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>The symbol tilde '''~''' is used to match a pattern for a particular field number.<br><br>The '''tilde character''' '''~''' is used to search for a pattern or display standard output for a particular field.<br><br>
