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Tutorial10: Sed & Awk Utilities

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# Issue a Linux command to create a directory called '''sed'''

# Issue a Linux command to change to the '''sed''' directory and confirm that you are located in the '''sed''' directory.

# Issue the following Linux command to copy the data.txt file ('''copy and paste''' to save time): cp ~uli101/tutorialfiles/data.txt ~/sed

# Issue the '''more''' command to quickly view the contents of the '''data.txt''' file. When finished, exit the more command by pressing the letter q[[Image:sed-1.png|thumb|right|300px|Issuing the '''p''' instruction without using the '''-n''' option (to suppress original output) will display lines twice.]] The '''p''' instruction with the '''sed''' command is used to '''print''' (i.e. ''display'') the contents of a text file.

# Issue the following Linux command: sed 'p' data.txt '''NOTE: You should notice that each line appears twice'''. The reason why standard output appears twice is that the sed command (without the '''-n option''') displays all lines regardless of an address used. We will use '''pipeline commands''' to both display stdout to the screen and save to files for confirmation of running these pipeline commands when run a '''checking-script''' later in this investigation.

# Issue a Linux command to create a directory called '''awk'''

# Issue a Linux command to change to the '''awk''' directory and confirm you are located in the '''awk''' directory. Let's download a database file that contains information regarding classic cars.

# Issue the following linux command: cp ~uli101/tutorialfiles/cars.txt ~/awk

# Issue the '''cat''' command to quickly view the contents of the '''cars.txt''' file. The "'''print'''" action (command) is the default action of awk to print all selected lines that match a '''pattern'''. This '''action''' (contained in braces) can provide more options such as printing '''specific fields''' of selected lines (or records) from a database. [[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''': awk '/ford/ {print}' cars.txt We will use '''pipeline commands''' to both display stdout to the screen and save to files for confirmation of running these pipeline commands when run a '''checking-script''' later in this investigation.

# Issue the following linux pipeline command to display the '''car make''', '''year''' and '''quantity''' of cars that '''begin''' with the '''letter 'f'''': awk '$1 ~ /^f/ {print $1,$2,$4}' cars.txt | tee awk-6.txt [[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 by using '''compound operator''' symbols: '''&&'''     (and) '''||'''        (or)

# Issue the following linux pipeline command to list all '''fords''' whose '''price is greater than $10,000''': awk '$1 ~ /ford/ && $5 > 10000 {print $0}' cars.txt | tee awk-7.txt

# Issue the following linux command: cp ~uli101/tutorialfiles/cars2.txt ~/awk

# Issue the '''cat''' command to quickly view the contents of the '''cars2.txt''' file.

# Issue the following linux pipeline command to display the '''year''' and '''quantity''' of cars that '''begin''' with the '''letter 'f'''' for the '''cars2.txt''' database: awk '$1 ~ /^f/ {print $2,$4}' cars2.txt | tee awk-8.txt What did you notice? The problem is that the '''cars2.txt''' database separates each field by a semi-colon (''';''') instead of '''TAB'''. Therefore, it does not recognize the second and fourth fields. You need to issue awk with the -F option to indicate that this file's fields are separated (delimited) by a semi-colorn.

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