bash random number in range

John D K -

To generate random number in range in bash or shell scripts we can use the shuf command.

(1) shuf - random numbers inclusive range

shuf -i 0-100 -n 2

result:

55
69

where:

  • -i - defines the inclusive range: min and max
  • -n - number of the random numbers to be produced

(2) RANDOM numbers from range

ceil=10
floor=1
echo $(((RANDOM % $(($ceil- $floor))) + $floor))

to run it as script don't set #!/bin/bash and run it by ./test.sh. To learn more about shell scripts check: How to Write Script in Bash?

(3) assign random number to variable

#!/bin/bash
var=$(shuf -i 0-100 -n 1)
echo $var

more about this: How to store bash shuf to string

(4) append random number to string

var=$(shuf -i 0-100 -n 1)
text="Hello "
echo "${text}${var}"

result:

Hello 47

(5) generate N random numbers from range

min=0
max=100
n=3
for i in $(seq $n); do
	shuf -i $min-$max -n 1
done

result:

65
29
70

(6) bash generate random N digit number

random 6 digit number

((RND=RANDOM<<15|RANDOM)) ; echo ${RND: -6}

random 8 digit number

((RND=RANDOM<<15|RANDOM)) ; echo ${RND: -8}

Note: that some numbers might start with 0 - 05838933

In this post we answer on those questions:

  • bash random number between 1 and 100
  • bash random range
  • bash random number between 0 and 1
  • bash random number fixed length
  • bash generate random 8 digit number