awk.md

AWK Command

Awk is a general-purpose scripting language designed for advanced text processing.

Working of AWK

For AWK, a text file or stream contains records and fields. AWK processes each record until finished.

Records are seperated by RS (default \n) and fields are seperated by FS (default space).

Fields are referenced using $ and a number starting from 1. $0 references entire record.

Built-in Variables

Built-in Variables Awk has a number of built-in variables that contain helpful information and allow you to control how the program is processed. Below are some of the most common built-in Variables:

NF - The number of fields in the record.

NR - The number of the current record.

FILENAME - The name of the input file that is currently processed.

FS - Field separator.

RS - Record separator.

OFS - Output field separator.

ORS - Output record separator.

Common Awk Statements

Awk supports different types of statements, including expressions, conditionals, input, output statements, and more. The most common awk statements are:

exit - Stops the execution of the whole program and exits.

next - Stops processing the current record and moves to the next record in the input data.

print - Print records, fields, variables, and custom text.

printf - Gives you more control over the output format, similar to C and bash printf .

Working with AWK

# inline awk program
awk 'program' file.txt                           # 'program' is awk code
awk -f program.txt file.txt                      # read awk code from file

# execute actions on every record
awk '{ print $1, $2 }' pops.txt
# find a record and execute an action on it
awk '/shoaib/ {print $2}' pops.txt
# action before beginning the program
awk 'BEGIN { print "STARTED" }; END { print "ENDING" }' filex.txt
# change builtin variables
awk 'BEGIN { FS="." }; { print $2 }' pops.txt
# using variables to do stuff
awk '{ sum += $3 } END { printf "%d\n", sum }' teams.txt