We have the following example file:


 tcpmux 1/tcp # TCP port service multiplexer
 tcpmux 1/udp # TCP port service multiplexer
 rje 5/tcp # Remote Job Entry
 rje 5/udp # Remote Job Entry
 echo 7/tcp
 echo 7/udp
 discard 9/tcp sink null
 discard 9/udp sink null
 systat 11/tcp users
 systat 11/udp users
 daytime 13/tcp
 daytime 13/udp
 qotd 17/tcp quote
 qotd 17/udp quote
 msp 18/tcp # message send protocol (historic)
 msp 18/udp # message send protocol (historic)
 chargen 19/tcp ttytst source
 chargen 19/udp ttytst source

How may we append the following lines to the beginning of the file? 


 # The latest IANA port assignments can be gotten from
 # http://www.iana.org/assignments/port-numbers
 # The Well Known Ports are those from 0 through 1023.
 # The Registered Ports are those from 1024 through 49151
 # The Dynamic and/or Private Ports are those from 49152 through 65535
 #
 # Each line describes one service, and is of the form:
 #
 # service-name port/protocol [aliases ...] [# comment]


So that the file will look like



 # The latest IANA port assignments can be gotten from
 # http://www.iana.org/assignments/port-numbers
 # The Well Known Ports are those from 0 through 1023.
 # The Registered Ports are those from 1024 through 49151
 # The Dynamic and/or Private Ports are those from 49152 through 65535
 #
 # Each line describes one service, and is of the form:
 #
 # service-name port/protocol [aliases ...] [# comment]
 tcpmux 1/tcp # TCP port service multiplexer
 tcpmux 1/udp # TCP port service multiplexer
 rje 5/tcp # Remote Job Entry
 rje 5/udp # Remote Job Entry
 echo 7/tcp
 echo 7/udp
 discard 9/tcp sink null
 discard 9/udp sink null
 systat 11/tcp users
 systat 11/udp users
 daytime 13/tcp
 daytime 13/udp
 qotd 17/tcp quote
 qotd 17/udp quote
 msp 18/tcp # message send protocol (historic)
 msp 18/udp # message send protocol (historic)
 chargen 19/tcp ttytst source
 chargen 19/udp ttytst source




The simple solution is to copy the original file to `file.bck`
and then append the new lines to the file
and then append `file.bck` to the file

**but this isn't elegant solution**