How can I can insert the contents of a file into another file right before a specific line

Question

How can I can insert the contents of a file into another file right before a specific line using sed?

example I have file1.xml that has the following:

Answer 1

I tried the different solutions and the one from Beta did the work for me.

Summary :

• I wanted to insert different files into a main file
• I wanted to use markers to say where I wanted these files to be inserted

Example :
Create 2 files :

cloud_config.yml:

coreos:
__ETCD2__

etcd2.yml :

  etcd2:
    name:                         __HOSTNAME__
    listen-peer-urls:             http://__IP_PUBLIC__:2380
    listen-client-urls:           http://__IP_PUBLIC__:2379,http://127.0.0.1:2379

Then we run that script on it :

sed '/Standard/i __ETCD2__' cloud_config.yml \
| sed -e "/__ETCD2__/r etcd2.yml" > tmpfile
sed "s|__ETCD2__||g" tmpfile > cloud_config.yml

Finally, we got that :

coreos:
  etcd2:
    name:                         __HOSTNAME__
    listen-peer-urls:             http://__IP_PUBLIC__:2380
    listen-client-urls:           http://__IP_PUBLIC__:2379,http://127.0.0.1:2379