awk

GNU Awk Cheatsheet #

GNU Awk (gawk) is the GNU implementation of the awk programming language, providing additional features beyond the POSIX standard.

Basic Syntax #

Command/Option	Example	Description
`gawk '{print $1}' file.txt`	`gawk '{print $1}' data.txt`	Print the first field of each line from the file
`gawk '/pattern/' file.txt`	`gawk '/error/' log.txt`	Print lines that match the pattern
`gawk '{print $1, $3}' file.txt`	`gawk '{print $1, $3}' data.txt`	Print the first and third fields from each line
`gawk -F, '{print $1}' file.csv`	`gawk -F, '{print $1}' data.csv`	Print the first field from a comma-separated file

Field Separators #

Command/Option	Example	Description
`gawk -F ' ' '{print $1}' file.txt`	`gawk -F ' ' '{print $1}' data.txt`	Set space as the field separator
`gawk -F ':' '{print $1}' file.txt`	`gawk -F ':' '{print $1}' passwd.txt`	Set colon as the field separator

Patterns and Actions #

Command/Option	Example	Description
`gawk '$3 > 50' file.txt`	`gawk '$3 > 50' data.txt`	Print lines where the third field is greater than 50
`gawk '{sum += $2} END {print sum}' file.txt`	`gawk '{sum += $2} END {print sum}' sales.txt`	Sum the values in the second field and print the total
`gawk 'BEGIN {FS=","; OFS="\t"} {print $1, $2}' file.csv`	`gawk 'BEGIN {FS=","; OFS="\t"} {print $1, $2}' data.csv`	Set input field separator to comma and output field separator to tab

Built-in Variables #

Command/Option	Example	Description
`gawk 'NR==1 {print $0}' file.txt`	`gawk 'NR==1 {print $0}' data.txt`	Print the first line of the file (NR is the record number)
`gawk 'END {print NR}' file.txt`	`gawk 'END {print NR}' data.txt`	Print the number of lines in the file

Extensions and Features #

Command/Option	Example	Description
`gawk --lint script.awk`	`gawk --lint process.awk`	Enable warnings about deprecated features
`gawk --version`	`gawk --version`	Display the version of GNU Awk

This cheatsheet provides essential GNU Awk (gawk) commands for text processing and data extraction.