Multiple lines from one with sed - sed

Question

Is there some way in sed to create multiple output lines from a single input line? I have a template file (there are more lines in the file, I'm just simplifying it):
http://hostname:#PORT#
I am currently using sed to replace #PORT# with a real port. However, I'd like to be able to pass in multiple ports, and have sed create a line for each. Is that possible?

Answer 1

I'm assuming you would want to duplicate the whole line for each port number. In that case it's easier to think of it as replacing the port numbers with the URL:
$ cat ports.in
1
2
3
4
5
$ sed 's#^\([0-9]*\$)#http://hostname:\1#' ports.in
http://hostname:1
http://hostname:2
http://hostname:3
http://hostname:4
http://hostname:5
To do it the other way around is easier with awk:
$ cat url.in
http://hostname:#PORT#
$ awk '/^[0-9]/ {ports[++i]=$0} /^http/ {sub(":#PORT#", ":%d\n"); for (p in ports) printf($0, ports[p])}' ports.in url.in
http://hostname:2
http://hostname:3
http://hostname:4
http://hostname:5
http://hostname:1
This reads both ports.in and url.in, and if a line starts with a number it is assumed that it's a port number from ports.in. Otherwise, if the line starts with http it's assumed to be an URL from url.in and will replace the port placeholder with a printf formatting string and then print the URL once for each port number read. It will fail to do the right thing if the files are fed in the wrong order.
A similar solution, but taking the URL from a shell variable:
$ myurl="http://hostname:#PORT#"
$ awk -v url="$myurl" 'BEGIN{sub(":#PORT#", ":%d\n",url)} /^[0-9]/ {ports[++i]=$0} END {for (p in ports) printf(url, ports[p])}' ports.in
http://hostname:2
http://hostname:3
http://hostname:4
http://hostname:5
http://hostname:1

Answer 2

It seems you have multiple templates and multiple ports to apply to them. Here's how to do it in a shell script (tested with bash), but you'll need to do it in two sed executions if you want to keep it simple because you have two multiply valued inputs. It is mathematically a cross product of the templates and the substitution values.
ports='80
8080
8081'
templates='http://domain1.net:%PORT/
http://domain2.org:%PORT/
http://domain3.com:%PORT/'
meta="s/(.*)/g; s|%PORT|\1|p; /p"
sed="`echo \"$ports\" |sed -rn \"$meta\" |tr '\n' ' '`"
echo "$templates" |sed -rn "h; $sed"
The shell variable meta is a meta sed script because it writes another sed script. The h saves the pattern buffer in the sed hold space. The sed commands generated from the meta sed recall, substitute, and print for each port. This is the result.
http://domain1.net:80/
http://domain1.net:8080/
http://domain1.net:8081/
http://domain2.org:80/
http://domain2.org:8080/
http://domain2.org:8081/
http://domain3.com:80/
http://domain3.com:8080/
http://domain3.com:8081/