awk.guide

emp.data
Beth       4.00     0
Dan        3.75     0
Kathy      4.00     10
Mark       5.00     20
Mary       5.50     22
Susie      4.25     18



String concatenation
awk '{ names = names $2 " " } END { print names }' emp.data

Length of words
awk '{ print , length() }' emp.data
Beth 4
Dan 3
Kathy 5
Mark 4
Mary 4
Susie 5

Counting lines, words, and characters
awk '{ nc = nc + length($0) + 1; nw = nw + NF; } END { print NR, "lines, ", nw, "words, " nc, "characters" }' emp.data

If-Else statement
awk '$2 > 2 { n = n + 1; pay = pay + $2 * $3 } END { if (n > 0) print n, "employees, total pay is", pay, "avarage pay is", pay/n; else print "no employees are paid more than $6/hour" }' emp.data 
6 employees, total pay is 337.5 avarage pay is 56.25

For statement
awk -f interest2 data

data

1000 .5 5
1000 .6 6
1000 .7 7

# interest2 - compute compound interest
# input: amount rate years
# output: compounded value at the end each year

{  for (i = 1; i <= $3; i = i + 1)
      printf("\t%.2f\n", $1 * (1 + $2) ^ i)
}

While statement

# intererst1

{ i = 1
  while (i <= $3) {
     printf("\t%.2f\n", $1 * (1 + $2) ^ i)
     i = i + 1
  }
}

awk -f interest1 data

Arrays
awk '{ line[NR] = $0}  END { i = NR; while (i > 0) { print line[i]; i = i -1 } }' emp.data
Susie      4.25     18
Mary       5.50     22
Mark       5.00     20
Kathy      4.00     10
Dan        3.75     0
Beth       4.00     0

For statement
{ line[NR] = $0 }

END { for (i = NR; i > 0; i = i -1)
        print line[i]
}

BEGIN and END
awk 'BEGIN {FS = " "; printf("%10s %6s %5s  %s\n\n", "COUNTRY", "AREA", "POP", "CONTINENT")}{printf("%10s %6d %5d   %s\n", $1, $2, $3, $4); area = area + $2; pop = pop + $3}; END {printf("\n%10s %6d %5d\n", "TOTAL", area, pop)}' countries
   COUNTRY   AREA   POP  CONTINENT

      USSR   8649   275   Asia
    Canada   3852    25   North
     China   3705  1032   Asia
       USA   3615   237   North
    Brazil   3286   134   South
     India   1267   746   Asia
    Mexico    762    78   North
    France    211    55   Europe
     Japan    144   120   Asia
   Germany     96    61   Europe
   England     94    56   Europe

     TOTAL  25681  2819
Arrays
awk '/Asia/ { pop["Asia"] += $3 }; /Europe/ { pop["Europe"] += $3 }; END { print "Asian population is", pop["Asia"], "million."; print "European population is", pop["Europe"], "million." }' countries
Asian population is 2173 million.
European population is 172 million

awk '{ x[NR] = $0 }; END { for (i = NR; i > 0; i--) print x[i] }' emp.data
Susie      4.25     18
Mary       5.50     22
Mark       5.00     20
Kathy      4.00     10
Dan        3.75     0
Beth       4.00     0