randint with range and float to int approximation

README.md

@@ -3,7 +3,7 @@
 My collection of useful shell scripts.
 
 ### randint.sh 
-usage: randint \<positive integer\> \[fast\]   
+usage: randint \<positive integer\>   
 print in the terminal a random integer x with $` 0 \leq x \leq \$1`$
 
 ### killwine.sh 

randint.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 if ! [[ "$1" =~ ^[0-9]+$ ]]; then
-    echo "Usage: randint <positive integer> [fast]"
+    echo "Usage: randint <positive integer>"
     exit 1
 fi
 number=$1
@@ -8,13 +8,10 @@ ceiling=$(echo "l($number +1)/l(2)" | bc -l | awk '{
     bits = ($1 == int($1)) ? $1 : int($1) + 1;
     print int( (bits + 7) / 8 )
 }')
-
-if [[ "$2" == "fast" ]]; then
-    random_num=$(xxd -p -l $ceiling /dev/urandom | tr -d '\n' | awk -v num="$number+1" '{print strtonum("0x" $0) % num}')
-else
-    while :; do
-        random_num=$(xxd -p -l $ceiling /dev/urandom | tr -d '\n' | awk '{print strtonum("0x" $0)}')
-        (( random_num < number )) && break
-    done
-fi
+random_num=$(xxd -p -l $ceiling /dev/urandom | tr -d '\n' | \
+    awk -v max="$number" -v scale="$ceiling" '{
+        val = strtonum("0x" $0);
+        range = 2**(scale*8);
+        print int(val * max / range)
+    }')
 echo $random_num