Shell Programming and Scripting

 #!/bin/bash
INPF=${1:-a.txt};
KWDS=${2:-lst}
cnt=0;
grep -v '^#' $KWDS | while read kwd;
do
        grep -q $kwd $INPF;
        if [ $? -eq 0 ]; then
                echo Found;
                ((cnt=cnt+1));
        fi
done
echo $cnt;

 /tmp$ cat a.txt 
ABC
XYZ
abc
xyz
/tmp$ cat lst
123
qwe
abc
zxc

 Found
0

Found
1

bash --version
GNU bash, version 3.2.39(1)-release (i486-pc-linux-gnu)
Copyright (C) 2007 Free Software Foundation, Inc.

# KSH
subshell | local-shell

# Bourne-compliant SH
local-shell | subshell

POSIX?  : cnt=$(( $cnt +1 ))
POSIX?  : cnt=$[ $cnt + 1 ]
C-style : ((cnt++))

cnt=$(($cnt + 1))
      and
cnt=$((cnt + 1))

INPF=${1:-file1};
KWDS=${2:-file2}
cnt=0;
while read kwd;
        do grep -q $kwd $INPF;
           if [ $? -eq 0 ]; then
                echo    Found;  
                ((cnt=cnt+1));
           fi
        done  < <(grep -v '^#' $KWDS) 
echo $cnt;

#!/bin/bash
shopt -s lastpipe
INPF=${1:-a.txt}
KWDS=${2:-lst}
cnt=0
grep -v '^#' $KWDS | while read kwd
do
        grep -q $kwd $INPF
        if [ $? -eq 0 ]; then
                echo Found
                ((cnt=cnt+1))
        fi
done
echo $cnt

Found
1