The break Statement

The break statement jumps out of the innermost for, while, or do loop that encloses it. The following example finds the smallest divisor of any integer, and also identifies prime numbers:

awk '# find smallest divisor of num
     { num = $1
       for (div = 2; div*div <= num; div++)
         if (num % div == 0)
           break
       if (num % div == 0)
         printf "Smallest divisor of %d is %d\n", num, div
       else
         printf "%d is prime\n", num
     }'

When the remainder is zero in the first if statement, awk immediately breaks out of the containing for loop. This means that awk proceeds immediately to the statement following the loop and continues processing. (This is very different from the exit statement which stops the entire awk program. See section The exit Statement.)

Here is another program equivalent to the previous one. It illustrates how the condition of a for or while could just as well be replaced with a break inside an if:

awk '# find smallest divisor of num
     { num = $1
       for (div = 2; ; div++) {
         if (num % div == 0) {
           printf "Smallest divisor of %d is %d\n", num, div
           break
         }
         if (div*div > num) {
           printf "%d is prime\n", num
           break
         }
       }
}'

As described above, the break statement has no meaning when used outside the body of a loop. However, although it was never documented, historical implementations of awk have treated the break statement outside of a loop as if it were a next statement (see section The next Statement). Recent versions of Unix awk no longer allow this usage. gawk will support this use of break only if `--traditional' has been specified on the command line (see section Command Line Options). Otherwise, it will be treated as an error, since the POSIX standard specifies that break should only be used inside the body of a loop (d.c.).

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