http://ru.wikipedia.org/wiki/AWK

http://lib.ru/MAN/DEMOS210/awk.txt

$ awk '{print}' /etc/passwd

$ awk '{print $0}' /etc/passwd

$ awk -F: '{print $1 " " $7}' /etc/passwd

$ awk '/^user/ {print $0}' /etc/passwd

$ awk -F: '!/sh$/ {print $1}' /etc/passwd

$ awk -F: 'BEGIN {print "Users used /bin/sh:"; count=0} /bin\/sh$/ {print $1; count++} END {print "Summary:" count " users"}' /etc/passwd

с какой строки начинается и от кого письмо

$ ee ex1.awk

$ cat ex1.awk
BEGIN {st=1}
/^$/ {st=1} 
/^From/ {if (st==1) 
                {print "String " NR; print $0; st=0}
        } 
!/^$/ {st=0}

$ awk -f ex1.awk /var/mail/uX
String 1
From u0@server.class Tue Oct 18 10:05:44 2005
String 21
From u0@server.class Tue Oct 18 10:05:49 2005
String 41
From u5@server.class Tue Oct 18 10:05:49 2005

Переслать отдельное письмо:

tail -n +21 /var/mail/uX | formail -1 -s sendmail val@bmstu.ru

$ vi wares.txt

$ cat wares.txt
table:34
car:24
apple:23
car:12

$ vi ex2.awk

$ cat ex2.awk
{
        M[$1]+=$2
} 
END {
        for (i in M) {
                print "sum " i "=" M[i]
        }
}

$ awk -F: -f ex2.awk wares.txt
sum apple=23
sum car=36
sum table=34