You need to replace a string with special characters (like http://) and don't want to do that manually?
I've found the solution.
I tried to escape each '/' with '/' but
sed didn't like that.
Instead of replacing each '/' just replace the placeholders for the regular expression with '#'!
Like this :
$ sed -i.bak s#http://your-address.com/images/#https://s3-eu-west-1.amazonaws.com/cf.img/posts/#g *
-i.bak is need, to prevent sed to cry around, it will make a backup of the files that you can simply remove with
- at the end means 'search all files'
I found the solution on this forum