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c4f4t0r
Asked: 2015-03-12 12:47:42 +0800 CST

Why don't random numbers in AWK change after the first run?

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I'm studying AWK, and when I use the following command for the second time why are the numbers always the same?

First time run:

awk 'BEGIN{for(i=1;i<=10;i++) print int(101*rand())}'
24
29
85
15
59
19
81
17
48
15

Second time run:

awk 'BEGIN{for(i=1;i<=10;i++) print int(101*rand())}'
24
29
85
15
59
19
81
17
48
15
linux

1 Answers

  1. Best Answer

    From https://www.gnu.org/software/gawk/manual/html_node/Numeric-Functions.html

    CAUTION: In most awk implementations, including gawk, rand() starts generating numbers from the same starting number, or seed, each time you run awk. Thus, a program generates the same results each time you run it. The numbers are random within one awk run but predictable from run to run. This is convenient for debugging, but if you want a program to do different things each time it is used, you must change the seed to a value that is different in each run. To do this, use srand().

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