Question

I’ve got a script which writes an ip address to a file ip.txt

I want to replace an ip address in an html file with the ip from ip.txt.

I’ve got a sed regex expression that matches an ip address, and I want to replace this matched text with the contents of ip.txt:

"s/\([0-9]\{1,3\}\.\)\{3\}[0-9]\{1,3\}//g"

How can I get sed to pull the contents of ip.txt and put it in the expression s/<search>/<*HERE*>/g?

Is there a better way to do it than this?

sed -e "s/\([0-9]\{1,3\}\.\)\{3\}[0-9]\{1,3\}/"`cat ip.txt`"/g"

Answer 1

You can read the IP into a shell variable before running the sed command. Assuming that ip.txt is a single line containing only the IP address:

read -r ip < ip.txt
sed -e "s/\([0-9]\{1,3\}\.\)\{3\}[0-9]\{1,3\}/$ip/g" file.html > newfile.html
mv newfile.html file.html