Generating random number between 1 and 10 in Bash Shell Script
BashBash Problem Overview
How would I generate an inclusive random number between 1 to 10 in Bash Shell Script?
Would it be $(RANDOM 1+10)?
Bash Solutions
Solution 1 - Bash
$(( ( RANDOM % 10 ) + 1 ))
EDIT. Changed brackets into parenthesis according to the comment. http://web.archive.org/web/20150206070451/http://islandlinux.org/howto/generate-random-numbers-bash-scripting
Solution 2 - Bash
Simplest solution would be to use tool which allows you to directly specify ranges, like [tag:GNU] shuf
shuf -i1-10 -n1
If you want to use $RANDOM, it would be more precise to throw out the last 8 numbers in 0...32767, and just treat it as 0...32759, since taking 0...32767 mod 10 you get the following distribution
0-8 each: 3277
8-9 each: 3276
So, slightly slower but more precise would be
while :; do ran=$RANDOM; ((ran < 32760)) && echo $(((ran%10)+1)) && break; done
Solution 3 - Bash
To generate random numbers with bash use the $RANDOM internal Bash function. Note that $RANDOM should not be used to generate an encryption key. $RANDOM is generated by using your current process ID (PID) and the current time/date as defined by the number of seconds elapsed since 1970.
echo $RANDOM % 10 + 1 | bc
Solution 4 - Bash
You can also use /dev/urandom:
grep -m1 -ao '[0-9]' /dev/urandom | sed s/0/10/ | head -n1
Solution 5 - Bash
To generate in the range: {0,..,9}
r=$(( $RANDOM % 10 )); echo $r
To generate in the range: {40,..,49}
r=$(( $RANDOM % 10 + 40 )); echo $r
Solution 6 - Bash
Here is example of pseudo-random generator when neither $RANDOM nor /dev/urandom is available
> echo $(date +%S) | grep -o .$ | sed s/0/10/