awk-filtering.sh

#!/bin/bash

# Print only lines matching expression
awk -F: '/ssh/ { print } ' /etc/group

# Print only if field 4 matchs expression
awk -F: 'match($4,/ssh/) { print } ' /etc/group

# Print field 1 only if field 4 matchs expression
awk -F: 'match($4,/ssh/) { print $1 } ' /etc/group

# Print text before printing all file
awk 'BEGIN {print "The File Contents:"} {print $0}' /etc/group

# Print footer
awk 'BEGIN {} {print $0}  END {print "File footer"}' /etc/group

# Print sum of numbers
awk '{sum += $1} END {print sum}' test.txt

# Print number of lines in file
awk 'END { print NR }' /etc/group

# Replace only first instance in line
awk '{sub(/HTML/, "html")}; 1' data.txt > data_new.txt

# Replace all instances in line
awk '{gsub(/HTML/, "html")}; 1' data.txt > data_new.txt

# Replace all instances of "foo" with "bar"
awk '{gsub(/foo/,"bar");print}'

# Swap first two columns of every line
awk '{temp=$1; $1=$2; $2=temp} 1' data.txt

# Delete second column from every line
awk '{ $2 = ""; print }' data.txt

# Print all except lines containing pattern
awk '!/ssh/ {print }' /etc/group

# Print all except lines containing pattern starting in line 5
awk '! /ssh/ { if (NR>4) print}' /etc/group

# Print last field
awk '{ print $NF }' /etc/group