Where the value of the counter variable was? linux -bash

Question

I wanted to know where it is changing the counter variable, I use it to count mail addresses contained in a file, when I print out the cycle, the value disappears from the terminal, on the other hand if the print within the cycle, the value is correct. So I do not understand where the value is lost, and I must print out the cycle as it is right

    cat $FILENAME_2 | while read LINE
 do
   if [ "$LINE" = "" ]
   then
    echo "blanks"
    exit 1
  fi 
  TEST=${LINE:0:1}
//verify string start with  #    
  if [  "$TEST" != "#"  ] ; then
  let CONTADOR=CONTADOR+1 
  cat html_list | mail -a "Content-type:text/html" -s "$ASUNTO" $LINE
  echo "Mail enviado a $LINE"
   fi   
echo "i send $CONTADOR mails" //print mails count
 done
echo "i send $CONTADOR mails" // print blank space

Answer 1

The value of the variable is lost because when you use | you fork a new subshell. The variable CONTADOR is created in the sub-shell. When you come out of it (ie after done ) that variable holds no value.

The right way to read a file is

while read LINE; do  
  # do stuff here 
done < "$FILENAME_2"

Read more about using a while loop for reading data at BashFAQ/001 .