randint

README.md

@@ -2,6 +2,10 @@
 
 My collection of useful shell scripts.
 
+### randint.sh 
+usage: randint <positive integer>   
+print in the terminal a random integer x with $` 0 \leq x \lt \$1`$
+
 ### killwine.sh 
 kill every wine process including processes hanging
 

randint.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+if ! [[ "$1" =~ ^[0-9]+$ ]]; then
+    echo "Usage: randint <positive integer>"
+    exit 1
+fi
+number=$1
+ceiling=$(echo "l($number +1)/l(2)" | bc -l | awk '{
+    bits = ($1 == int($1)) ? $1 : int($1) + 1;
+    print int( (bits + 7) / 8 )
+}')
+random_num=$(xxd -p -l $ceiling /dev/urandom | tr -d '\n' | awk -v num="$number" '{print strtonum("0x" $0) % num}')
+echo $random_num