Examples

Print sum and average

awk -F: '{sum += $3}
     END { print sum, sum/NR }
' /etc/passwd

Printing parameters

awk 'BEGIN {
    for (i = 1; i < ARGC; i++)
        print ARGV[i] }' a b c

Output field separator as a comma

awk 'BEGIN { FS=":";OFS=","}
 {print $1,$2,$3,$4}' /etc/passwd

Position of match

awk 'BEGIN {
    if (match("One Two Three", "Tw"))
        print RSTART }'

Length of match

awk 'BEGIN {
    if (match("One Two Three", "re"))
        print RLENGTH }'