If you need to push multiple lines to one file through a bash script, you can simply use that syntax:
cat > /etc/ntp.conf << _NTPconf_ server 1.2.3.4 server 5.6.7.8 _NTPconf_
Tip: Be aware that if you’re using indentation, last line should not be indented (this would lead you to some errors).
If you want to add line instead of overwriting file (like we did in the previous example), just replace the “>” with “>>” after cat command.
cat >> /etc/ntp.conf << _NTPconf_ server 1.2.3.4 server 5.6.7.8 _NTPconf_