Crazy golf attempt at Jaro-Winkler algorithm (untested v0.01), per https://codegolf.stackexchange.com/questions/95619/string-similarity-using-jaro-winkler

jarow.sh

#!/usr/local/bin/bash
#set -x
a="${1,,}" b="${2,,}" x="$a" y="$b"
[ ${#b} -gt ${#a} ]&&x="$b" y="$a";  # y is shorter
h=$((${#y}/2+1))   # h = limit for char matching
# Substring matching routine
r(){ k=${#1} l=${#2} g="$2" s=""  # k,l = length of strings 1,2
  for((i=0;i<k;i++)){     # iterate over string1
    p="${1:i:1}"          # p is the i'th characted of $1
    v=$((i-h<0?0:i-h))    # minimum for exploring string2
    w=$((i+h>l?l:i+h))    # maximum for exploring string2
    for((j=v;j<w;j++)){    # iterate over part of string2
      q="${g:j:1}"        # q is the j'th character of g, aka $2
      # match found
      [ "$p" = "$q" ]&&{
        s="$s$p"
        # replace $2 match with a dot (.) as (*) can cause major headaches
        c=$((j<0?0:j))  # safety: start at 0 (but j > w is unlikely)
        g="${g::j}.${g:j+1}"
        break
      }
    }
  }
  echo $s
}
m=`r "$x" "$y"`
n=`r "$y" "$x"`
#check length of returned substrings
d=${#m}
e=${#n}
o=$((d==0|e==0|d!=e?0:1))
[ $o -eq 0 ]&&{ echo 0.0;exit;}
# Transposition routine
t(){ u=0
  for((i=0;i<${#1};i++)){
    [ "${1:i:1}" != "${2:i:1}" ]&&((u++));
  }
  echo $((u/2))
}
#get transposn. between matching sets
z=`t "$m" "$n"`
#now get jw distance
bc -l<<<"( $d/${#y} + $e/${#x} + ($d-$z)/$d )/3"