Add a new line with string to multiple files

make-draft.bash

# I needed to not publish posts from past.
# Note: this is slow if you are doing for thousands of files

for file in `ls 200*`; do 
echo $file

grep "draft = true" $file # looking for this string if already present. 
if [[ $? == 1 ]]; then # if the string is not found. grep returns status 1
echo "string not found"
tempfile=123.txt # creating a temporary file
tac $file | sed '$d' > $tempfile # remove the last line from the main file
echo -e "draft = true\n+++" >> $tempfile # add draft = true along with the removed line 
tac $tempfile > $file # reverse and put it back in the original file
rm $tempfile # delete the temporary file
fi

done