Insert a line after first pattern match via sed stream editor.
In the files with names starting with dhp-story under current directory, find the line that starts with :oldurl:, insert the following line after the matched line:
sed -i '/:oldurl:/a :author: 護法法師' dhp-story*
Tested on Ubuntu Linux 15.10, sed 4.2.2-6.1.
|||[Python] Insert Line With Matched Pattern|