Changes

Tutorial11: Sed & Awk Utilities

71 bytes added, 09:56, 4 March 2021

→‎INVESTIGATION 2: USING THE AWK UTILITY

# Issue the '''more''' command to quickly view the contents of the '''cars.txt''' file. When finished, exit the more command by pressing the letter q 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.

# Issue the following linux command all to display records in the "cars.txt" database that contain the make "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 all to display records in the "cars.txt" database that contain the make "ford": awk '/ford/' cars.txt | tee awk-1.txt What do you notice?You should notice ALL lines displayed without using a search criteria. You can use variables with the "print" action for further processing. We will discuss the following variables in this tutorial: '''$0''' - Current record (entire line) '''$1''' - First field in record '''$n''' - nth field in record '''NR''' - Record Number (order in database) '''NF''' - Number of fields in current record For a listing of more variables, please consult your course notes. The '''tilde character''' '''~''' is used to search for a pattern or display standard output for a particular field.

# Issue the following linux pipeline command to display the model, year, quantity and price in the "cars.txt" database for makes of "chevy": awk '/chevy/ {print $2,$3,$4,$5}' cars.txt | tee awk-2.txt Notice that a space " " is the delimiter for the fields that appear as standard output.

# Issue the following linux pipeline command to display all plymouths (plyms) by model name, price and quantity: awk '/chevy/ {print $2,$3,$4,$5}' cars.txt | tee awk-3.txt 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 Comparison Operators: '''<'''     Less than '''<='''   Less than or equal '''>'''     Greater than '''>='''   Greater than or equal '''=='''   Equal '''!='''    Not equal

Msaul

Administrators

13,420

edits

CDOT Wiki β

Changes

Tutorial11: Sed & Awk Utilities

CDOT Wiki ^β