Shell Programming and Scripting

sed 's/\(.*=.*\)bad/\1good/g' file

while IFS='=' read A B
do
   if echo "$B" | grep -q bad
   then
      echo "$A=${B//bad/good}" >>file2
   else
      echo "$A=$B" >>file1
   fi
done <file
cat file1 file2 > newfile
rm file1 file2
cat newfile

grep -E '*.=*.bad' file > file2
grep -vE '*.=*.bad' file > newfile
sed 's/\(.*=.*\)bad/\1good/g' file2 >> newfile
rm file2
cat newfile

while IFS='=' read A B
do
   C="${B//bad/good}"
   [ "$B" = "$C" ]
   N=$?
   echo "$A=$C" >>file$N
done <file
cat file0 file1 > newfile
rm file0 file1
cat newfile