#!/bin/sh


# w=blah.txt;
# w=blah_txtx;
 w=blah_txt;     # This was a problem

ext="bla .bla txt .txt \.txt .bmp";

echo;

echo "-----  filter user string \$ext ----";
echo "\$ext= $ext";
ext=${ext//\\}           # removes  all escape characters
ext=${ext//./\\.}       # replaces all . with \.
echo "\$ext= $ext";

echo;
echo "----- test strings: -----";
echo;
echo "  \$w test line: $w";
echo "\$ext test list: $ext";
echo; 
echo "---- 1 ---------------------";
for ea in $ext; do 
  echo -n "try [[ $w =~ $ea ]] : ";
  if [[ $w =~ $ea ]]; then 
    echo "YES ";
  else
    echo "NO  ";
  fi;
done;
echo;
echo "---- 2 ---------------------";
for ea in $ext; do
  echo -n "try [[ $w =~ $ea$ ]] : ";
  if [[ $w =~ $ea$ ]]; then
    echo "YES";
  else
    echo "NO ";
  fi;
done;