Write an IP with Netmask (sed)

Question

I have a problem. I want to write an IP into a file with sed

newsource=1.2.3.4/24
sed -i 's/.*#source*/&\n'"$newsource"'/' file

$newsource is an IP, which CAN contain a net-mask /24 or not. Right now the sed writes the full IP but not the /24. How can I change that?

Answer 1

This is because you must either escape your /, or change the sed separator to something else:

escape: \/

newsource=1.2.3.4\/24
sed -i 's/.*#source*/&\n'"$newsource"'/' file

or

change sed separator to ~

newsource=1.2.3.4/24
sed -i 's~.*#source*~&\n'"$newsource"'~' file

Share and enjoy.

Answer 2

Try:

sed -i 's|.*#source*|&\n'"${newsource}"'|' file

You could use \ to escape the / but since the path is stored in a variable it's probably easier to use a different separator.