Shell Programming and Scripting

#!/bin/ksh
set -x
date1_data=abc.txt
date2_data=bcd.txt
if diff $date1_data $date2_data >/dev/null ; then
   echo "Equal"
else
   echo "Not Equal"
  fi

#!/bin/ksh
set -x
date1_data=abc.txt
date2_data=bcd.txt
if not diff $date1_data $date2_data >/dev/null ; then
   echo "NotEqual"
  fi

diff filea fileb > /dev/null
rc=$?
[ $rc > 1 ] && echo 'fatal error'  && exit 1
[ $rc -eq 0 ] && echo 'same'
[ $rc -eq 1] && echo 'different'

diff file1 file2 || echo "not equal"