xxxxxxxxxx
sed -i -e 's/yourpattern/yourpatternXXXTTTXXX/g' -i -e 's/XXXTTTXXX/\n/g' file
^add some unique pattern here
# -i update the file , try without -i
xxxxxxxxxx
#add some lines from a file to 78 line of my file
sed -i -e '78r../../insert_file' File_you_change.txt
#-i update the file ,
xxxxxxxxxx
For substituting with newline use sed command to replace a match with a
not used char and tr command to replace that char with a newline '\n'
#For example:
echo "123." | sed -E 's/([[:digit:]]*)\./\1|next line/' | tr '|' '\n'