#! /bin/bash 
# Last edited on 2015-10-27 23:35:08 by stolfilocal

x="$1"; shift;

i=0;
j=${#x};
j=$(( $j - 1 ))
  
while [[ $i -lt $j ]]; do
  xi="${x:$i:1}"
  xj="${x:$j:1}"
  if [[ "/$xi" == "/ " ]]; then
    i=$(( $i + 1 ))
    continue
  elif [[ "/$xj" == "/ " ]]; then
    j=$(( $j - 1 ))
    continue
  elif [[ "/$xi" != "/$xj" ]]; then
    echo "FAIL:" "${x:0:$i}" "$xi" "$xj" "${x:$j}" 1>&2
    exit 1;
  fi
  i=$(( $i + 1 ))
  j=$(( $j - 1 ));
done
echo "OK" 1>&2
exit 0