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In Bash, you can use either integers or floating point numbers to generate random numbers. A bash script can be used to create random numbers within a given range or size. This article demonstrates various ways to generate random numbers in Bash.

$RANDOMGenerate random numbers using variables

$RANDOMA variable can be used to generate random numbers or a range of random values ​​between 0and 32767. However, you can $RANDOMlimit the range of numbers used to generate random numbers by dividing the value by a specific value.

To generate a random number between 0 and 32767, use the following command:

$ echo $RANDOM

Output:

28091

$RANDOMYou can generate random numbers from a specific range by dividing the variable by the remainder value. It contains $double brackets with a (()).

To generate a random number between 1 and 100, use the following command:

$ echo $(( $RANDOM % 100 + 1 ))

Output:

19

Since the percent sign causes the mathematical operation modulo to fail, the number 100 (the remainder after the division) will never be reached. If the random generator returns the value 100, the modulo operation will provide the value 0.

Use shufthe command to generate random numbers

You can shufgenerate large numbers in shell scripts using the command.

The following command creates a single integer between 0 and 100:

$ shuf -i 0-100 -n1

Output:

76

In the above command, -irepresents the input range, -nrepresents the number of people. The key -nfollowed by any positive number represents the number of random numbers generated. Run the following command to print five random numbers between 0 and 100.

$ shuf -i 0-100 -n5

Output:

68
78
24
76
41

/dev/urandomGenerate random numbers using

/dev/urandomDevice files allow you to generate $RANDOMpseudo-random numbers that are more random than variables. However, getting those numbers into variables in your script requires further work, such as odfiltering through , as shown in the example.

od /dev/urandom  -A n -t d -N 1

-t dThe option indicates that signed decimal should be used as the output format, -N 1telling the program to /dev/urandomget a byte from .

Output:

124

Generate random numbers using awk

awkThe rand()function returns a random floating point number in the range 0-1. BEGINThe following command will be executed before the next step.

awk 'BEGIN{x=rand(); print x}'

Output:

0.444937